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Control of a 3-phase 4-leg active power filter under non-ideal mains voltage condition
Abstract
In this paper, instantaneous reactive power theory (IRP), also known as p–q theory based a new control algorithm is proposed for 3-phase 4-wire and 4-leg shunt active power filter (APF) to suppress harmonic currents, compensate reactive power and neutral line current and balance the load currents under unbalanced non-linear load and non-ideal mains voltage conditions. The APF is composed from 4-leg voltage source inverter (VSI) with a common DC-link capacitor and hysteresis–band PWM current controller. In order to show validity of the proposed control algorithm, compared conventional p–q and p–q–r theory, four different cases such as ideal and unbalanced and balanced-distorted and unbalanced-distorted mains voltage conditions are considered and then simulated. All simulations are performed by using Matlab-Simulink Power System Blockset. The performance of the 4-leg APF with the proposed control algorithm is found considerably effective and adequate to compensate harmonics, reactive power and neutral current and balance load currents under all non-ideal mains voltage scenarios.
... Classifications based on phase connections are discussed in [46][47][48][49][50][51][52] and are depicted in Figure 8. They are classified as single-phase two-wire (2W), three-phase three-wire (3W) and four-wire (4W) connections. ...
... Several structures and controlling methods of single-phase APF with single-phase nonlinear loads [49,50] are discussed. The function of three-phase 3W [40,41] and three-phase 4W [51,52] APFs are discussed in this work. These APFs are engaged to suppress the issues of PQ in the utility system. ...
... A volume of work based upon control techniques of APFs is discussed in [51,52]. This segment demonstrates the different control techniques of APFs. ...
Power Quality (PQ) has become an important aspect in today’s power system scenario. PQ issues are also raised not only in normal three-phase systems but also with the integration of different distributed generations (DGs), including renewable energy sources, storage systems, and other systems like a diesel generator, fuel cells, etc. The prevalence of these issues is due to the existence of non-linear features and because of the rapid changing of power electronics devices such as switch-mode converters for adjustable speed drives and a diode or thyristor rectifiers. The wide use of these fast switching devices in the utility system leads to the increase of disturbances associated with harmonics and reactive power. The occurrence of PQ disturbances in turn creates several unwanted effects in the utility system. Therefore, many researchers are working on the enhancement of PQ using different custom power devices (CPDs). In this paper, the authors highlight the importance of the PQ in the utility network, its effect, and its solution using different CPDs like passive, active, and hybrid filters. Further, the authors point out several compensation strategies including reference signal generation and gating signal strategies. In addition, this paper also presents the role of the active filter in different DG systems. Some technical and economic considerations, future developments are also discussed in this literature. For easy reference, a volume of journals of more than 140 publications on the particular subject is reported. The effectiveness of our study will help the researchers to choose the proper control methodology and compensation strategy for various applications of APF for improving the PQ.
... A reference voltage value is used to evaluate the real DC-link capacitor voltage and the error is regulated by a PI controller which acts for the voltage regulator circuit. Equations (13) and (14) signify the necessary compensating current desired (i * Ƚ, i * Ⱦǡ i * Ȗ) in Į-ȕ-Ȗ coordinates to satisfy the load required power. The next transformation is to obtain the desired compensation currents in a-b-c coordinates: ...
... Lastly, neutral desired current is calculated as follows [13]: ...
... A hysteresis-band is used for current error value to produce the pattern of switching for the inverter. The main drawbacks of the HCC are inconstant switching frequency and high ripples in current [13,14]. Also, the switching losses are high which limits the application of HCC to low levels of power [15]. ...
... wire of the power system [1]. Second, four-leg topology which is a more complex topology due to higher number of semiconductor switches employed and an additional control input [2]. In this work, the split capacitor topology is preferred for its less complicated structure. ...
... Note that the process of generating reference current always comes together with the process of extracting harmonic current and synchronization phases from the power line. Although many techniques have been developed for this particular purpose [4,5], two techniques are reported to be extensively applied in three-phase four-wire system, namely direct-quadrature-zero dq0 principle [1,6,7] and instantaneous power pq0 theory [2,7,8]. Nevertheless, dq0 principle is preferred in this work for its reduced control complexity. ...
... Further details are presented in Sections 3 and 4. Meanwhile, to regulate dc-link voltage and maintain voltage balance of the split dc-link capacitor, the conventional proportional-integral (PI) technique is adopted due to its straightforward feature [1,11]. Lastly, to generate switching pulses, a standard hysteresis band current control (HBC) technique is applied as it offers the benefits of structure simplicity and quick current controllability [1,2,6]. Figure 2 shows control structure of a standard dq0 technique which is commonly applied for the purpose of generating reference current. ...
This paper presents a non-iterative technique that generates reference current to manage operation of a three-phase four-wire shunt active power filter which employs a three-leg split capacitor voltage source inverter (VSI) topology. The proposed technique integrates together a self-tuning-filter (STF) and direct-quadrature-zero (dq0) principle (referred here as STF-dq0), allowing the controlled shunt active power filter (SAPF) to perform effectively under distorted source voltages and unbalanced load conditions. Unlike the previous technique developed based on the standard dq0 principle, the proposed technique does not require any service from a phase-locked loop (PLL) where two STFs are applied to separate harmonic and fundamental elements for the purpose of generating synchronization phases and reference current, respectively. Simulation work which includes connection of the SAPF circuits, design of control techniques and all the necessary assessments are conducted in MATLAB-Simulink platform. Performance achieved by the SAPF while utilizing the proposed technique is thoroughly investigated and benchmarked with that demonstrated by the SAPF while using the standard dq0 technique, to evaluate the inherent advantages. Exhaustive simulation results are provided and thoroughly discussed to support design concept, effectiveness, and benefits of the proposed technique.
... Nonlinear load harmonic currents that go unfiltered propagate through the ac system and result in voltage distortion due to transmission line impedance voltage drop at harmonic frequencies [69]. Nearby customers and apparatus connected to the distorted ac system will be negatively affected as distorted voltages may cause increased harmonic current distortion [8], overheating of power factor correction capacitors, motors, transformers, cables, and maloperation of protective devices [44]. ...
... Two dc bus configurations are possible, a single capacitor or a split capacitor voltage source inverter, Fig. 5 [35]. Configuration in Fig. 5 (b) requires, in addition to voltage regulation, voltage balancing of the two capacitors [69]. ...
... IGBT technology is used for the multilevel structure (Taher et al., 2009;Liu et al., 2005). PWM multi carrier control strategy is the extension of the PWM algorithm to control the individual switches in multilevel topologies and is capable of generating multilevel voltage waveforms with reduced power loss within the converter (Ucar and Ozdemir, 2008;Bouhali et al., 2007). ...
... The dynamic model of UPFC is derived by performing standard d-q transformation of the current through the series transformer and shunt transformer (Gholipour and Saadate, 2005;Fujita et al., 2006). They are given below (ω is the angular frequency of the voltages and currents (Ucar and Ozdemir, 2008). ...
... IGBT technology is used for the multilevel structure (Taher et al., 2009;Liu et al., 2005). PWM multi carrier control strategy is the extension of the PWM algorithm to control the individual switches in multilevel topologies and is capable of generating multilevel voltage waveforms with reduced power loss within the converter (Ucar and Ozdemir, 2008;Bouhali et al., 2007). ...
... The dynamic model of UPFC is derived by performing standard d-q transformation of the current through the series transformer and shunt transformer (Gholipour and Saadate, 2005;Fujita et al., 2006). They are given below (ω is the angular frequency of the voltages and currents (Ucar and Ozdemir, 2008). ...
... Luego de la transformación de los voltajes de fase y las corrientes de línea en la carga al marco de referencia (α, β, 0), las corrientes en el marco de referencia (p, q, r) se obtienen con la ecuación (Ucar y Ozdemir, 2008), Donde e αβ y e αβ0 están dados por la ecuación . ...
... El algoritmo pqr propone calcular las corrientes de compensación en el marco (p, q, r) con la ecuación para obtener corrientes sinusoidales y balanceadas en la fuente de alimentación (Ucar y Ozdemir, 2008), ...
Contexto: Una de las funciones de un filtro activo
de potencia es calcular las consignas de corriente
(i.e.: reducción de armónicos, corrección del factor
de potencia, balancear las corrientes y voltajes)
que compensen la fuente de alimentación. Existen
en la literatura varios algortimos que realizan esta
función. El objetivo de este artículo es presentar los
resultados obtenidos sobre el funcionamiento de
cinco algoritmos propuestos en la literatura, bajo
condiciones de voltajes distorsionados.
... Luego de la transformación de los voltajes de fase y las corrientes de línea en la carga al marco de referencia (α, β, 0), las corrientes en el marco de referencia (p, q, r) se obtienen con la ecuación (Ucar y Ozdemir, 2008), Donde e αβ y e αβ0 están dados por la ecuación . ...
... El algoritmo pqr propone calcular las corrientes de compensación en el marco (p, q, r) con la ecuación para obtener corrientes sinusoidales y balanceadas en la fuente de alimentación (Ucar y Ozdemir, 2008), ...
Contexto: Una de las funciones de un filtro activo de potencia es calcular las consignas de corriente (i.e.: reducción de armónicos, corrección del factor de potencia, balancear las corrientes y voltajes) que compensen la fuente de alimentación. Existen en la literatura varios algoritmos que realizan esta función. El objetivo de este artículo es presentar los resultados obtenidos sobre el funcionamiento de cinco algoritmos propuestos en la literatura, bajo condiciones de voltajes distorsionados.
Método: Consiste en la implementación de los siguientes algoritmos: potencia reactiva instantánea; factor de potencia unitario; compensación perfecta de armónicos; algoritmo pqr; y marco de referencia síncrono, en el programa de simulación Matlab – Simulink. Luego, usando un sistema eléctrico compuesto por cargas lineales y no lineales con características similares a un circuito real, se calcula la distorsión armónica total, el valor eficaz de la corriente de línea y de su componente fundamental, y el factor de potencia en la fuente trifásica. Se tomarán valores antes y después de la conexión a la red del filtro activo de potencia, considerando cada uno de los algoritmos por separado y manteniendo las mismas condiciones en el sistema para cada uno de ellos. También se calculan otras cantidades en el sistema de potencia para realizar la comparación.
Resultados: Se muestran las corrientes de la red de alimentación antes y después de la conexión del filtro activo de potencia, además de la distorsión armónica de las corrientes y el factor de potencia. También se presenta la forma de onda del voltaje de continua del inversor con cada uno de los algoritmos utilizados, para evaluar el desempeño de un controlador de tensión que requiere el filtro.
Conclusiones: En condiciones de funcionamiento con voltajes distorsionados en la red de alimentación, el algoritmo con mejor desempeño es el de compensación perfecta de armónicos, ya que este utiliza un filtro pasa bajo para mitigar los efectos de los armónicos de los voltajes sobre el cálculo de las corrientes de compensación.
... Much effort is being put [12] towards simplifying the controller to improve the power quality. An instantaneous power control scheme has been recommended for the 3-phase 4-wire system in [13] to indemnify reactive power and suppress harmonic currents. Authors in [14] proposed a photovoltaic (PV) integrated unified power quality conditioner (UPQC) based on pq theory control for the estimation of the reference signals which further improves the power quality. ...
Photovoltaic-based Unified Power Quality Conditioner (PV-UPQC) is one of the custom power devices widely employed for power quality improvement. A simplified control strategy is proposed for the PV-UPQC system with the objective to regulate the dc-link voltage, compensate the harmonics in grid current, and provide suitable control during a sudden change in the grid side or load side. Individual series and shunt converters in UPQC are controlled based on simplified instantaneous active and reactive power control theory that ultimately improves the power quality. Besides, active and reactive power flow between the PV, grid and load is also managed while maintaining the minimum dc-link ripple and balanced dc-link voltage. Interfacing inductors on both ends limits the high-frequency components. Different test cases are simulated in the Simulink platform to show the effectiveness in providing robust control for compensating power quality problems.
... This topology has shown to be superior. more controllability [6] compared to the traditional three-leg four-wire however, the latter is preferable due to its lower cost. power semiconductor devices in number. ...
In order to enhance the quality of the electricity in microgrids powered by renewable energy, this study introduces a three-phase Active Power Conditioner. The six IGBT bridge is managed by three hysteresis controllers. Disturbances in a microgrid, which is a fragile electrical grid, can be crucial. The Active Power Conditioner (APC), which is described in this paper, serves as a bridge between the microgrid's AC bus and renewable energy sources. The implementation of an upgraded control technique allows for the injection of electrical energy from renewable sources while also enhancing power quality inside the same microgrid. THDI (Total Harmonic Distortion), PF (Power Factor), and current can all be improved with the help of the control approach known as Extended Indirect Control Strategy.
... Using Clarke's transformation, the three-phase current and voltages are transformed to the α-β plane. Before the transformation, those signals are passed through a first-order Butterworth filter to remove ripples [20,41]. ...
Due to the energy crisis and exhaustion in the amount of fossil fuels left, there is an urge to increase the penetration of renewables in the grid. This paper deals with the design and control of a hybrid microgrid (HMG) in the presence of variable renewable energy sources. The DC sub-grid consists of a permanent magnet synchronous generator (PMSG) wind turbine, solar PV array with a perturb-and-observe (P&O) MPPT algorithm, boost converter, and battery energy storage system (BESS) with DC loads. The AC sub-grid consists of a PMSG wind turbine and a fuel cell with an inverter circuit synchronized to the grid to meet its load demand. A bidirectional interlinking converter (IC) connects the AC sub-grid and DC sub-grid, which facilitates power exchange between them. The decentralized control of converters allows all the renewables to operate in coordination independently without communication between them. The proposed control algorithm of the IC enables it to act as an active power filter in addition to the power exchange operation. The active power filtering feature of the IC helps to retain the power quality of the microgrid as per IEEE 519 standards by providing reactive power support and reducing the harmonic levels to less than 5%. The HMG with the proposed algorithm can operate in both grid-connected and islanded modes. While operating in grid-connected mode, power exchange between DC and AC sub-grids takes place and all the load demands are met. If it is in islanded mode, a diesel generator supports the AC sub-grid to meet the critical load demands and the BESS supports the DC microgrid. The proposed model is designed and simulated using MATLAB-SIMULINK and its results are analyzed. The efficacy of the proposed control is highlighted by comparing it with the existing controls and testing the HMG for load variations.
... [93]. ...
Abstract
In an electrical network, the harmonic disturbances can strongly degrade customer power quality.
In order to improve power system quality, the three-phase three wire active filter showed its effectiveness in term of compensation of the harmonics generated by the nonlinear loads in a three-wire network.
The work presented in this memory more particularly relates to the control of three phase four wire active filter, different topologies and control strategies of the parallel active power filters to compensate current harmonics and reactive power in the four-wire electrical network is studied. These references identification methods were studied simulated then, compared on the basis of their effectiveness.
Keys words: Active filter, PLL, Non-Linear load, reactive power, network pollution, Active Compensator
ملخـــص
في الشبكات الكهربائية, الاضطرابات الناتجة عن الحمولات الكهربائية غير الخطية لها أثر سلبي على التجهيزات الكهربائية.
بهدف تحسين نوعية الطاقة الكهربائية, المرشحات ثلاثية الطور ذات ثلاث خطوط أثبتت كفاءتها من حيث تحسين الاضطرابات الناتجة عن الحمولات الكهربائية غير الخطية في الشبكات الكهربائية ذات ثلاث خطوط.
العمل المبين في هذه المذكرة معني خصوصا بالتحكم في المرشحات ثلاثية الطور ذات أربعة خطوط, لقد قمنا بدراسة لمختلف التركيبات ومختلف استراتيجيات التحكم في المرشحات النشيطة المتوازية والذي يسمح بتعويض الاضطرابات و الاستطاعة الردية و كذا فقدان التوازن في الشبكات الكهربائية ذات أربعة خطوط. كل طرق استخراج مراجع التيار قد درست و طبقت ثم قورنت من حيث الفعالية والكفاءة.
كلمـات مفتاحيـة : المرشحات النشيطة,PLL, الحمولات الكهربائية غير الخطية, معوض نشيط.
Résumé
Dans un réseau électrique les perturbations harmoniques ont des effets néfastes sur les équipements électriques.
Dans l’objectif d’améliorer la qualité de l’énergie électrique, Le filtre actif triphasé à trois fils a montré son efficacité en terme de compensation des harmoniques générés par les charges non linéaires et/ou déséquilibrées dans un réseau à trois fils.
Le travail présenté dans ce mémoire concerne plus particulièrement la commande d’un filtre actif à quatre fils, nous avons abordé, les différentes topologies et stratégies de commande des filtres actifs parallèles en vue de compenser les harmoniques de courants et la puissance réactive susceptible d’apparaître dans les réseau électriques à quatre fils. Ces méthodes d’identifications ont été simulées puis comparées sur leurs efficacités.
Mots clés : Filtrage actif, PLL, charges non linéaires, énergie réactive, compensateur actif.
... To mitigate the power quality problems associated with the use of line commutated rectifiers, passive and hybrid power filters [313], active power filters [314], multi-pulse rectifiers [315], and hybrid multi-pulse rectifiers [316], were used. Nevertheless, the emergence of fully controllable semiconductors has enabled the implementation of several power electronics solutions in the power quality field, which allow responding to these problems. ...
Nowadays, new challenges arise relating to the compensation of power quality problems, where the introduction of innovative solutions based on power electronics is of paramount importance. The evolution from conventional electrical power grids to smart grids requires the use of a large number of power electronics converters, indispensable for the integration of key technologies, such as renewable energies, electric mobility and energy storage systems, which adds importance to power quality issues. Addressing these topics, this paper presents an extensive review on power electronics technologies applied to power quality improvement, highlighting, and explaining the main phenomena associated with the occurrence of power quality problems in smart grids, their cause and effects for different activity sectors, and the main power electronics topologies for each technological solution. More specifically, the paper presents a review and classification of the main power quality problems and the respective context with the standards, a review of power quality problems related to the power production from renewables, the contextualization with solid-state transformers, electric mobility and electrical railway systems, a review of power electronics solutions to compensate the main power quality problems, as well as power electronics solutions to guarantee high levels of power quality. Relevant experimental results and exemplificative developed power electronics prototypes are also presented throughout the paper.
... Then p-q-r theory in [95] and [96] was presented as a candidate for the compensation of neutral current in balanced and unbalanced diet. It offers two types of compensation, either through the powers either by currents. ...
The change in the nature of energy production which mainly used fossil resources and which is becoming increasingly clean with various renewable sources such as wind turbines; photovoltaic panels is reflected in a paradigm shift where decentralized production takes precedence on centralized production. In addition, technological progress has considerably changed uses with the intensive diffusion of charges based on power electronics, which are certainly economical but very polluting, which directly affects the quality of energy.
The work carried out in this thesis focused on improving the quality of electrical energy via compensators connected to the electrical network. It is devoted to the PBT method (Power Balance Theory) generic solution that we offer. We present its principle on networks on the three-phase 3-wire network using in one hand SAPF as simple 3 phase inverter with simple capacitor as DC link source, in the other hand, we use SAPF as a Z source inverter with photovoltaic cells based MPPT P&O algorithm. For this command, we present the different simulation results for the different regimes (transient and permanent), with the different states of the electrical network (unbalanced and / or distorted).
Key words: Power Balance Theory; THD; SAPF; Anti-windup Regulation; Unbalanced grid.
Resumé
Le changement de nature de la production d'énergie qui utilise principalement des ressources fossiles et qui devient de plus en plus propre avec diverses sources renouvelables telles que les éoliennes, les panneaux photovoltaïques se traduit par un changement de paradigme où la production décentralisée prime sur la production centralisée. De plus, les progrès technologiques ont considérablement modifié les usages avec la diffusion intensive de charges basées sur l'électronique de puissance, certes économiques mais très polluantes, ce qui affecte directement la qualité de l'énergie.
Les travaux menés dans cette thèse ont porté sur l'amélioration de la qualité de l'énergie électrique via des compensateurs connectés au réseau électrique. Il est consacré à la solution générique de la méthode PBT (Power Balance Theory) que nous proposons. Nous présentons son principe sur les réseaux triphasés utilisant d'une part SAPF comme simple onduleur triphasé avec un simple condensateur comme source de liaison CC, d'autre part, nous utilisons SAPF comme onduleur source Z avec cellules photovoltaïques basé sur l'algorithme MPPT P&O. Pour cette commande, nous présentons les différents résultats de simulation pour les différents régimes (transitoire et permanent), avec les différents états du réseau électrique (déséquilibré et / ou déformé).
Mots clés : Théorie de l'équilibre de Puissance ; THD ; FAP ; Règlement anti-liquidation ; Grille déséquilibrée.
ملــــــــخص
ينعكس التغيير في طبيعة إنتاج الطاقة التي تستخدم بشكل أساسي الموارد الأحفورية والتي أصبحت أكثر نظافة مع العديد من المصادر المتجددة مثل توربينات الرياح والألواح الكهروضوئية في تحول نموذجي حيث يكون للإنتاج اللامركزي الأسبقية على الإنتاج المركزي. بالإضافة إلى ذلك، أدى التقدم التكنولوجي إلى تغيير الاستخدامات بشكل كبير مع الانتشار المكثف للشحنات القائمة على إلكترونيات الطاقة، والتي تعتبر بالتأكيد اقتصادية ولكنها ملوثة للغاية، مما يؤثر بشكل مباشر على جودة الطاقة.
ركز العمل المنفذ في هذه الرسالة على تحسين جودة الطاقة الكهربائية عبر المعوضات المتصلة بالشبكة الكهربائية. إنه مكرس لطريقة PBT (نظرية توازن الطاقة) التي نقدمها. نقدم مبدأها على الشبكات ثلاثية الطور باستخدام SAPF في يد واحدة كعاكس بسيط ثلاثي الطور مع مكثف بسيط كمصدر رابط DC، ومن ناحية أخرى، نستخدم SAPF كمصدر Z مع الخلايا الكهروضوئية خوارزمية MPPT P&O القائمة. بالنسبة لهذا الأمر، نقدم نتائج المحاكاة المختلفة للأنظمة المختلفة (عابرة ودائمة)، مع حالات مختلفة للشبكة الكهربائية (غير متوازنة و / أو مشوهة).
الكلمات المفتاحية: نظرية توازن القوى. مجموع التشويه التوافقي مرشح نشط متوازي لوائح مكافحة التصفية؛ شبكة غير متوازنة.
... In order to solve the power quality problems originated by the passive converters, traditional methods have been used, such as the application of passive inductive filters in series, or capacitive filters in parallel (or both) or the use of multi-pulse rectifiers [5,10]. Active power filters can be used to reduce harmonic current distortion through the production of compensating currents, in case of the shunt active power filter, and to reduce the harmonic voltage distortion through the production of compensating voltages, in the case of the series active power filter [11]. ...
The three-phase induction motor is the main electric motor used in industrial applications, contributing significantly to the industrial electricity consumption. Additionally, the traditional variable speed drivers, due to the internal constitution based on a passive rectifier, contribute to accentuate power quality problems on the grid side. In this context, this paper presents thesimulation, implementation and subsequent experimental verification of an electronic variable speed drive for three-phase induction motors, which is composed by a three-phase ac-dc converter on the grid side and by a three-phase dc-ac converter on the motor side. With the proposed solution, besides driving the motor, it is possible to mitigate power quality problems on the grid side (e.g., current harmonics and reactive power) associated with the use of diode-bridge ac-dc converters in the conventional variable speed drives. Besides, with the proposed solution, a bidirectional operation is possible, allowing to deliver to the power grid the energy generated in motor braking processes. As demonstrated along the paper, with the proposed variable speed drive it is possible to control the motor speed (including the rotation direction), and to achieve operation with sinusoidal currents and unitary power factor on the grid side. A laboratory prototype was developed, allowing to perform experimental validation and to verify the main functionalities of the variable speed drive.
... Generally, four-wire APCs have been conceived using fourleg converters [5]. This topology has proved better controllability [6] than the classical three-leg four-wire converter but the latter is preferred because of its lower number of power semiconductor devices. In this paper, it is shown that using an adequate control strategy, even with a simple three-leg four-wire system, it is possible to mitigate disturbances like voltage unbalance. ...
... In fact, zero line may be overheated or causes a fire as a result of the excessive harmonic current [2]. For this reason, three-phase four-wire active filters (3P4WSAF) are recommended in distribution systems [3,4]. ...
This paper deals with three-phase four-wire shunt active filter to improve power quality. It proposes backstepping control based on Lyapunov theory for the filter dc side voltage, and a modified synchronous reference frame approach based on two self-tuning filters for the identification of harmonic currents. The voltage source inverter of shunt active filter has a four-leg two-level topology. It is controlled by hysteresis. The proposed shunt active filter is verified by simulation and experimental validation. Backstepping control, an approach for nonlinear systems, leads to good dynamic and static performance in the dc side voltage control. Three-phase four-wire shunt active filter using the modified synchronous reference frame approach reduced the total harmonic distortion in the tested operating conditions.
... Conceptual functionality of SAPF in a three-phase four-wire system is presented in this section. To perform a mitigation operation in a three-phase four-wire system, two types of topologies can be considered for SAPF: three-phase three-leg with two dc-link capacitors split at neutral-point [23,25] and three-phase four-leg topologies [26]. In this work, a standard three-phase three-leg topology is adopted, and the circuit connection is illustrated in Figure 1. ...
This paper presents the enhancements performed on the adaptive linear neuron (ADALINE) technique so that it can be applied for active power filtering purposes in a three-phase four-wire system. In the context of active power filtering, the ADALINE technique which was initially developed for a single-phase two-wire system has been further expanded to suit three-phase three-wire system. For both systems, ADALINE techniques have been reported to be effective even when the grid voltage is distorted and/or unbalanced. However, further works that study the possibility to apply ADALINE technique in a three-phase four-wire system which invariably carries unbalanced loads, are rather limited. Hence, in this work, a control algorithm (named as enhanced-ADALINE) which combines the strength of highly selective filter (HSF), ADALINE concept and averaging function is proposed, to manage harmonics mitigation by shunt active power filter (SAPF) under non-ideal grid and unbalanced load scenarios. MATLAB-Simulink software is utilized to conduct an exhaustive simulation study which includes circuit connection of SAPF in a three-phase four-wire system, design of control algorithms, and performance assessments. Benchmarking with the existing algorithm is performed to examine the benefits of using the proposed algorithm. From the analysis, simulation findings are presented and thoroughly discussed to verify design concept, capability, and relevance of the proposed algorithm.
... La red de alimentación del circuito de potencia es una fuente trifásica de tensiones distorsionadas con un THD de 6,34 %, como normalmente se encuentra en la práctica. Los voltajes de fase de la fuente de alimentación se rigen por la ecuación (14), tal como se expuso en [24]. ...
El presente artículo evalúa el desempeño de un filtro activo empleando tres diferentes técnicas de control de corriente de banda de histéresis: banda fija, banda adaptativa y con modulación por vector espacial. En la comparación se estudian las características de cada técnica y mediante simulación se evalúa su desempeño y operación. En todos los casos se emplea la teoría pq para el cálculo de las corrientes de referencia y se emplea un controlador proporcional para regular la tensión del bus de continua. De acuerdo con los resultados, las técnicas PWM evaluadas permiten una reducción del contenido armónico de la corriente de la red de alimentación de 31 % sin compensación, a un 6 %, considerando el filtro activo de potencia. La técnica de banda adaptativa de histéresis presenta el más bajo desempeño en la reducción de armónicos en las corrientes de la red. Además, se tiene que el método de banda fija de histéresis es el más recomendado para aplicaciones de filtros paralelo debido a que posee una estructura más simple que permite su implementación. Los resultados tambien muestran que la técnica de banda adaptativa de histéresis es la que presenta mayor reducción en las variaciones de la frecuencia de conmutación, requiriendo mayor número de operaciones, ya que requiere calcular el ancho de banda en cada iteración. Mientras que la técnica de modulación por vector espacial y banda de histéresis presenta frecuencias de conmutación altamente variables y mayor complejidad en su implementación.
... The distorted voltage waveform causes harmonic currents to be drawn by other loads connected at the point of common coupling (PCC). The existence of voltage and current harmonics in power systems decreases the power factor, increases losses in the lines, and can cause timing errors in sensitive electronic equipment (Ucar et al., 2008).Harmonics decline the power system performance and create conditions for equipment destroy. As a consequence, there is a stimulant for end users and utilities to limit harmonics.IEEE Standard 519 proposes to limit the amount of harmonics an end user can inject into the power system so the resulting voltage distortion falls within specified limits (IEEE Std. ...
The increase of the harmonics disturbance in the ac mains currents has become a major concern due to the wide spread of power electronics equipment in modern electrical systems. This paper presents the analysis and simulation of a three-phase active power filter (APF) compensating the harmonics and reactive power created by nonlinear in steady state and in transients using Matlab Simulink. An optimal control strategy for shunt active filter which is proposed in this paper, based on voltage source inverter using Modified Synchronous reference frame theory (SRF) and sinusoidal pulse width modulation (SPWM) Control. The target of this strategy is to improve the behavior of source current when it is crossing from zero. It is seen that the APF has effectively mitigate the Total Harmonic Distortion (THD). The FFT analysis of the active filter system brings the THD of the source current less than 5% into compliance with IEEE-519 harmonic standards.
... To design a filter, a clear knowledge of the desired response is required. When such knowledge is not available, in that case adaptive filter is used [1]- [5], [7]. The adjustment is directly proportional to the tap input vector u (n).In particular the adjustment applied to the tap-weight vector at iteration n+1 is -normalized‖ with respect to the squared Euclidean norm of the tap-input vector u(n) at iteration n-hence the term -normalized‖ [6], [17], [18]. ...
Harmonic in power line communication is an
important matter now a days. With the extensive usage of nonlinear
loads in power systems, the harmonic effect becomes more
prominent. Fast Fourier Transform (FFT) is one of the most
popular computation algorithms for harmonic analysis. In this
paper, single phase current waveform is taken from a three phase
supply fed to motor through power analyzer interfaced with PC.
FFT is done using matlab program on the imported data. After
that, same waveform like the current waveform obtained from the
hardware setup is designed in SIMULINK window of matlab7.5
version. Those designed waveforms are filtered by Recursive Least
Square (RLS) Filter to reduce Total Harmonic Distortion (THD)
in the filtered output and the response of Normalised Least Mean
Square (NLMS) for same input signal is discussed in detail in
author’s previous publication, given as reference. Adaptive signal
processing to eliminate harmonics is replicated again in Code
Composer Studio (CCS) using TMS320C6713 SIMULATOR
.Here comparison is done between the responses of RLS filter with
Normalised LMS filter. At last, the conclusion is drawn as NLMS
filter is superior than RLS filter in the field of power line
harmonic elimination to author’s best knowledge
... In addition to this, active power filters can also compensate reactive power, regulate terminal voltage, suppress flicker and improve voltage balance in three wire as well as four wire systems. For neutral current harmonic elimination, traditionally active power filters based on three-phase, four-wire inverter topology is implemented [12,13]. A conventional three phase four wire split capacitor based topology is shown in Figure 1. ...
Increased penetration of nonlinear loads like power electronic converter based systems have aggravated issue of harmonic injection in the power system. Neutral current harmonics is an issue of concern for three phase four wire system. This paper is focused on the elimination of neutral current harmonics with the help of shunt active power filter based on the star-delta transformer and single phase half bridge inverter. The presented active power filter eliminates harmonics present in neutral current which in turn helps in mitigating third harmonics from the supply mains. The topology has the advantage of reduced number of semiconducting devices and switching losses as compared to conventional three phase active filter. Simulation studies for the proposed active filter are presented and compared with the behavior of conventional three phase active filter. Experimental results for DSP based laboratory prototype of the proposed filter are shown to substantiate performance of system. Both simulations, as well as experimental results, demonstrate effective compensation provided by single phase half bridge inverter based active filter.
... Non-linear loads draw non-sinusoidal phase currents. The phasor sum of balanced nonsinusoidal 3Φ currents can produce current in the neutral conductor [7]. The problem due to high neutral current are: a) Wiring failure b) Common mode noise c) Flat-topping of voltage waveform and d) Overloading of distribution feeders and transformers. ...
The power quality compensator chosen in this paper is a DSTATCOM which integrates a three phase four leg Voltage Source Converter (VSC) with a DC capacitor. The major role of the DSTATCOM is to mitigate the components of harmonic/reactive current present in the line current thereby shapes the grid current to be sinusoidal and improves the power factor nearly unity under varying conditions. In addition DSATATCOM mitigates neutral current (Isn) and balances the load currents under unbalanced conditions in three phase four wire (3P4W) distribution system. The control strategy proposed for the DSTATCOM is a Neural Network (NN) based p-q-r theory with two Artificial Neural Network (ANN) controllers for a 3P4W distribution system. The reference signal for 3P3W Shunt Active Power Filter (SAPF) is calculated by implementing an ANN controller. The alleviation of Isn under unbalanced condition is achieved by another ANN controller which produces reference signal for the 1φ APF. The performance of the proposed DSTATCOM is analysed for various conditions through simulations in MATLAB SIMULINK and the simulation results justify the effectiveness of the propounded NN based control algorithm for DSTATCOM. © Copyright 2018 Institute of Advanced Engineering and Science. All rights reserved.
... This aim is complex by the fact that there are loads in the system that generate harmonic currents. These harmonic outcomes in distorted voltages and currents can harmfully crash the system performance in dissimilar ways [1], [2]. ...
The increase of power electronic converters at the end-user side is unavoidable and it will cause current harmonic distortion and wide range of disturbance in the power system (PS). This paper presents current harmonic compensation for the test case of the Quaid-e-Awam University College of Engineering Sciences and Technology (QUCEST) Larkana campus in MATLAB SIMULINK by using three types of power filters i.e. passive, active and hybrid power filters. The purpose of this experiment and simulation model is to analyse and find out the best solution for reducing the current harmonic and unbalanced load condition at the incoming transformer to the campus. Moreover, this paper presents the testing and comparison of the active and hybrid power filters by using the combined design technique of harmonic compensate control system based on Unit Vector Template (UVT) and Instantaneous Reactive Power (IRP) theory. The simulation results allow to identify the effectiveness of the control system along with passive filter. Based on the testing and simulation results of three types of power filters, hybrid power filter has the maximum ability to mitigate the current harmonic in the system, and it also reduces the neutral current thus causing less stress in the existing system. © 2017 Institute of Advanced Engineering and Science. All rights reserved.
... This aim is complex by the fact that there are loads in the system that generate harmonic currents. These harmonic outcomes in distorted voltages and currents can harmfully crash the system performance in dissimilar ways [1], [2]. ...
The increase of power electronic converters at the end-user side is unavoidable and it will cause current harmonic distortion and wide range of disturbance in the power system (PS). This paper presents current harmonic compensation for the test case of the Quaid-e-Awam University College of Engineering Sciences and Technology (QUCEST) Larkana campus in MATLAB SIMULINK by using three types of power filters i.e. passive, active and hybrid power filters. The purpose of this experiment and simulation model is to analyse and find out the best solution for reducing the current harmonic and unbalanced load condition at the incoming transformer to the campus. Moreover, this paper presents the testing and comparison of the active and hybrid power filters by using the combined design technique of harmonic compensate control system based on Unit Vector Template (UVT) and Instantaneous Reactive Power (IRP) theory. The simulation results allow to identify the effectiveness of the control system along with passive filter. Based on the testing and simulation results of three types of power filters, hybrid power filter has the maximum ability to mitigate the current harmonic in the system, and it also reduces the neutral current thus causing less stress in the existing system.
... The existence of current and voltage harmonics in the DS increases the power loss, reduces the PF and causes malfunctioning of highly sensitive electronic devices. The distribution transformer also gets overheated due to the presence of harmonic and unbalanced currents, which results in damage to winding insulation and failure of transformer operation (Ucar and Ozdemir 2008). ...
A four-leg distribution static compensator (FL-DSTATCOM) has been investigated to achieve harmonic elimination, supply current balancing, compensation of reactive power and current in the neutral conductor of a three-phase, four-wire distribution system with various types of static, dynamic and combined loads. The capability of FL-DSTATCOM for compensating reactive power under dynamic condition is evaluated with induction machine having variable load torque. Also, the performance of FL-DSTATCOM is evaluated with combined load, which is a combination of dynamic and unbalanced static loads. The FL-DSTATCOM injects reactive and harmonics components of load current extracted using synchronous reference frame theory. With FL-DSTATCOM, the unbalanced, harmonic and reactive loads will appear to the main power supply as balanced, linear and unity power factor load. Hence, the main power supply would deliver only fundamental frequency positive sequence components of load current. The switching pulses are generated by employing hysteresis current controller. MATLAB/SIMULINK has been used for capability evaluation under multifarious loading conditions considering IEEE standard 519. The simulation results prove that the FL-DSTATCOM is capable of making the supply current as balanced and sinusoidal, maintaining the PF at point of common coupling near to unity and reducing the supply neutral current very close to zero.
... The energy efficiency and power handling capacity is reduced because of low power factor. Due to the low power factor, the losses are more in electrical machines and appliances, torque pulsations in motor and furthermore creating perilous disturbances to connected devices in electric system [1]- [2]. Several techniques and equipment's are used to mitigate power quality related issues in the distribution system. ...
... It is demonstrated in [10] that the voltage distortion can exceed levels set by IEEE 519 [11] due to the progressive use of nonlinear devices. The SAPF was already presented as a solution for improving PQ [12][13][14][15][16][17][18][19][20][21]. But researches are needed to improve the quality of filtering. ...
This paper presents UPQC with various Boost converter device for reduce the receiving end voltage and sending end current ripples of existed conventional multi bus system. Unified Power Quality Conditioner (UPQC) is a dynamic FACT device transmission system. The UPQC configuration has the capabilities of these two devices, Voltage Regulators, Active Filters. It is noticed that the multi bus system with UPQC minimises the system losses. So UPQC increases the multi bus system performance. This paper also presents the suitable boost converter between PV system and UPQC capacitor to charge the capacitor. Here principle of operation and its implementation of boost converters for multi bus system are presented. Three various types of boost converters those are High Step Up type Boost Converter (HSBC), Double Inductor type Boost Converter (DIBC) and Inter Connected Boost Converter (ICBC) are used for comparative analysis. The comparison is done in boost converter output voltage, input current and those ripples, also transmitting real power and reactive powers. With MATLAB/SIMULINK results, Inter Connected Boost Converter (ICBC) is selected as best converter device in between Photo voltaic system, capacitor of UPQC.
Severe issues such as degradation of power quality and efficiency have surfaced in past few years due to extensive use of power electronic converters for conversion and control in power system. The shunt active power filter (SAPF) has gained attention as a competent solution among researchers. However, most SAPF control schemes render ineffective results under non-ideal supply conditions. A novel single-phase p – q scheme based on high selectivity filter (HSF) for extraction of reference compensation currents is proposed in this paper. A three H-bridges (3HB) voltage source inverter (VSI) topology of SAPF is considered and its dc-link voltage is regulated using an Enhanced Bacterial foraging optimization (BFO) based PI controller. This topology along with the proposed SAPF control scheme can guarantee improved APF performance as each phase of the three-phase four-wire system can be controlled independently. Extensive investigations are carried out using MATLAB/Simulink simulations followed by real-time performance verification in Opal-RT Lab. The effectiveness is assessed in terms of current harmonics, excessive neutral current and current unbalance compensation. The results obtained with proposed scheme when compared with conventional three-phase and single-phase p – q schemes employing low-pass filters (LPF) yield remarkably superior results under ideal, distorted and unbalanced supply and unbalanced loading conditions.
The development use power digital tools presents harmonics in the supply system which develops an issue in the high quality of power supplied. Great Power Quality is quite crucial for our everyday use home appliances in both commercial as well as residential fields. Scientists have actually attempted as well as applied several valuable innovation for eliminating all the voltage and also present relevant harmonic incident troubles which consequently enhances the high quality of power provided to the power system. The focal point of this thesis is the execution of control methods like SRF concept as well as immediate power for the procedure of Unified Power Quality Conditioner (UPQC) which is just one of the current modern technology that consists of both collection and also shunt energetic power filter operating at the very same time as well as thus boosts all the present as well as voltage relevant trouble like voltage sag/swell, flicker, and so on at the exact same time and also assists in decrease of Total Harmonic Distortion. Harmonic materials of the resource current has actually been determined as well as contrasted for the various situations to show the impact of harmonic removal circuit on the harmonic settlement quality of AC-DC power supply feeding to nonlinear tons. Simulation results gotten programs that the efficiency of compensator is located to be far better than without compensator.
This study proposes an APF grid-connecting solution to reduce harmonic at the moment of connecting transfer status. The work includes analyzing the system structure, the parameters of the passive LCL-filter system, the active power filter (APF) grid-connecting transfer status, the phase lock loop (PLL) for phase-matching connecting algorithms, and the Fuzzy-PI grid connection control based on d-q theory. To validate the accuracy of the proposed solution, simulation and experimental results shows that the power system is more stable by applying the transfer of the APF-connecting procedure. The proposed APF grid-connecting also reduces grid current’s THD, and matches phase between grid voltage and grid current.
-The presence of harmonic in power system is a major concern to power engineers. With the heavy usage of non-linear loads in power systems, the harmonic effect becomes more serious. One of the most popular computation algorithms for harmonic analyzer is Fast Fourier Transform (FFT). In this paper ,single phase current waveform is taken from a three phase supply fed to motor through power analyzer interfaced with PC. FFT is done using MATLAB program on the imported data. After that, same waveform like the current waveform obtained from the hardware setup is created in MATLAB SIMULINK window. That created waveform is filtered by Normalized LMS Filter to reduce Total Harmonic Distortion (THD) in the filtered output. Comparison is done between the hardware results with the software simulated results. THD value is reduced from at max 12.03% to at min 0.17%, which has set a new record to our best knowledge.
This work presents closed-loop results of DUPQC in Ten-Bus Distribution System (TBDS). Multiple DUPQCs have been used as a FACTS controller between sending-end-bus and receiving-end-bus. The goal of the suggested DUPQC system is to enhance the voltage and reduce THD using multiple DUPQCs. Block diagrams and Simulink models are developed for PI and FOPID controlled TBDS using two DUPQCs. Simulation studies are performed on DUPQC based TBDS and the results are presented. The results of bus voltages of PI and FOPID based TBD systems indicate that the time response with FOPID is superior to PI controlled TBDS.
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This article has been withdrawn as part of the withdrawal of the Proceedings of the International Conference on Emerging Trends in Materials Science, Technology and Engineering (ICMSTE2K21). Subsequent to acceptance of these Proceedings papers by the responsible Guest Editors, Dr S. Sakthivel, Dr S. Karthikeyan and Dr I. A. Palani, several serious concerns arose regarding the integrity and veracity of the conference organisation and peer-review process. After a thorough investigation, the peer-review process was confirmed to fall beneath the high standards expected by Materials Today: Proceedings.
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Distributed Unified Power Quality Conditioner (DUPQC) has been identified as a good FACTS controller between feeding end and far end of distribution system. The goal of the recommended closed loop DUPQC system is to enhance the dynamic response utilizing proportional resonant (PR), hysteresis controller (HC) and sliding mode (SM) controllers. Simulink models are designed for PR, HC and SMC controlled distributed UPQC-based ten bus systems. Computer results for three different reference values are presented for PRC, HC and SMC with reactive power. The results of PRC-, HC- and SMC-based DUPQC ten bus system indicate that voltage response with SMC is exceptional to PR and HC controlled DUPQC systems. Hence, SMC is proposed for the control of closed loop distribution system (CLDS) using DUPQC. SMC makes the CLDS to track the reference voltage with minimum steady-state error and settling time.
This paper proposes the application of a Dynamic Voltage Restorer (DVR) to enhance the power quality and analyzed the solar PV integrated unified power quality conditioner (PV-UPQC).The PV-UPQC is employed to maintain power quality under various current and voltage distortion. The PV-UPQC consists of a shunt and series compensators connected back to back with common DC-link. The shunt compensator performs the dual function of extracting power from PV array apart from compensating for load current harmonics. The series compensator compensates for the grid side power quality problems such as grid voltage sag and swell. In proposed system Dynamic Voltage Restorer (DVR) is used as a series compensator and also it enhance the power quality. The UPQC is eliminate power quality issues like unbalanced grid voltage with harmonics and load harmonics. The performance of the system are evaluated by simulating in MATLAB/Simulink environment under a nonlinear load.
In three dimensional (3D) space vector modulation (SVM) theory with α-β-γ frame there are some issues which are well known and are widely practiced being quite obvious but without any proof so far. In this paper necessary scientific foundations to those issues have been provided. The foremost of these issues has been with the frame of reference to be considered in 3D SVM applications for unbalanced three phase systems. Although for balanced three phase systems there has been no controversy with α-β frame as the frame of reference but in 3D it has not yet been established which one, α-β-γ frame or the a-b-c frame, is mathematically correct. Another significant issue addressed in this work has been to ascertain the exact reason when a three phase system has to be represented in 2D or 3D space to apply SVM. It has been presented for the first time in this work that the key factor that determines whether 3D or 2D SVM has to be applied depends on the presence of time independent symmetrical components in a three phase ac system. Also it has been proved that the third axis, the Y–axis, represents the time independent quantity and that it must be directed perpendicular to the α-β plane passing through the origin.
Many control techniques for three-phase active filters with the aim of improving the power factor and reducing the current harmonic distortion at the source level exist today and are widely reported in the scientific literature. Almost all of these methods are designed for a perfect sine-wave source and do not perform sinusoidal current when voltages are distorted or unbalanced. The work developed in this paper concerns the active filtering on a perturbed and unbalanced network. First, the proposed control method is described and validated by simulations and experimental results, and then the proposed method is compared to the classical control laws such as the original p-q theory, the modified p-q theory and the p−q−r method. Experimental results are conducted on a three-wire low power distribution network under perturbed voltage and non-linear load using a DSPACE control system. The assessment is performed on the source currents after filtering, and a comparative evaluation in terms of unbalance factor and current Total Harmonic Distortion (THDi) is carried out for all methods. © 2018 International Association for Mathematics and Computers in Simulation (IMACS)
The use of nonlinear loads and power electronics switches are increasing day by day and causing so many problems like, harmonics pollution, reactive power demand, low power factor etc. These problems are mitigated through Shunt Active Power Filter (SAPF) but the system robustness is depending on the control algorithm. In this article the Modified P-Q theory is implemented to mitigate power quality problems in distribution system and the results are compared with the existing SRF theory to prove the robustness of the controller. The designed active power filter compensates reactive power, current harmonic from distribution system with maintaining power factor near to unity and also reduces the burden of neutral conductor effectively with balanced source current through Modified P-Q theory over SRF theory.
Active Power Filter used to compensate the source currents in an electrical system. The controller, based on the well known p-q theory was implemented on a DSP and determines the reference currents to be generated by a 2-level inverter. Some experimental results are presented and compared with computer simulations obtained with EMTDC/PSCAD V4.2. Other simulation results that demonstrate some of the improvements that will be made to the implemented prototype are also presented.
This paper presents a new control strategy for parallel active
filters. The instantaneous positive sequence extraction of load current
and utility voltage is combined with the p-q theory. This method is able
to control a four leg active filter for compensation of reactive power,
current harmonics, three-phase imbalance and neutral current
cancellation simultaneously in 3-phase 4-wire distribution systems. The
presented method can operate in harmonic polluted and/or imbalance
utility voltage case. The simulation results prove the considerable
ability of control strategy to suppress the above-mentioned subjects
with a very fast dynamic response. This method is also usable in 3-wire
systems
form only given as follows. A new approach is presented for the design of a shunt active filter in a three-phase, four-wire distribution system with unbalanced, distorted sources and unbalanced loads. The purpose of the shunt active filter is to provide compensation currents such that the source needs to supply balanced (positive-sequence) fundamental source current at unity power factor even though the load consumes harmonic currents as well as positive, negative, and zero-sequence currents. A major feature of the proposed approach is that it does not require symmetrical component transformation to transform the three-phase voltages and currents to α-β-o quantities. This makes practical implementation of the proposed method easier than the symmetrical component transformation approach. In addition, the power factor of the positive-sequence fundamental component is close to unity and only positive-sequence power is supplied by the source. The effectiveness of the proposed control algorithm is demonstrated by computer simulation and experimental results of a shunt active filter for a three-phase four-wire distribution system with distorted, unbalanced source voltages and unbalanced loads
The performance of three-phase active power filters under nonideal voltage scenarios is investigated in this paper. It begins with the analysis of an instantaneous reactive power algorithm applied for the three-phase active power filter design, which was found to present poor performance under nonideal test scenarios. This motivates our proposed design of a new active power filter for solving such problems. In the proposed scheme, the circuit not only shows its effectiveness in the tests, but also implements with a simpler control circuit when compared with the other algorithm. The method has been implemented as a prototype and tested through various simulation cases, including ideal mains voltage, unbalanced three-phase mains voltage, and distorted mains voltage. Test results have demonstrated the feasibility and practicality of the proposed method approach for the applications.
In this paper, the authors propose a calculation method for the compensating current reference of the active power filter, where a nonlinear load exists in a three-phase, three-wire unsymmetrical voltage system. This new method has been named the extension pq method. The authors have experimented with the extension pq method and the pq method, using the same current-controlled intelligent power module inverter for both methods. The results of the experiments proved that in the unsymmetrical voltage system the source current was distorted in the case of the pq method, but undistorted in the case of the extension pq method.
This paper presents a new control algorithm for an active power filter (APF) to compensate harmonic and reactive power of a 3-phase thyristor bridge rectifier under non-ideal mains voltage scenarios. Sensing load current, dc bus voltage and source voltages compute reference currents of the APF. APF driving signals are produced with these signals via a hysteresis band current controller. Matlab/simulink power system toolbox is used to simulate the proposed system. The proposed method's performance is compared with conventional instantaneous power (p–q) theory. The simulation results are presented and discussed showing the effectiveness of the control algorithm. The proposed algorithm is found quite satisfactory to compensate the reactive power and harmonics under non-ideal mains voltage conditions. The increased performance of the active power filter under different non-sinusoidal mains voltage and dynamic load conditions are extensively demonstrated.
This paper proposes a novel power compensation algorithm in
three-phase four-wire power systems by using p-q-r theory. P-q-r theory
is compared with two previous instantaneous power theories, p-q theory
and cross-vector theory. P-q-r theory provides two-degrees of freedom to
control the system currents by only compensating the instantaneous
imaginary power without using any energy storage element. The definition
of powers maintains conservatism, and agrees well with the general
understanding of power. Simulation results show the superiority of p-q-r
theory both in definition and compensation
This paper deals with the design, analysis, and digital simulation
of a four-branches-inverter-based-active-filter, that compensates the
reactive power and eliminates the harmonic currents in the phases and
neutral of an unbalanced 3-phase 4-wires electrical distribution system,
feeding nonlinear loads. The active filter uses a
4-branches-DC/AC-inverter as the power stage. As in a typical active
filter, 3-branches are needed to compensate the three-phase currents and
one-branch compensates the neutral current. Simulation results are shown
to prove the active filter performance under different configurations
In this paper, the authors propose a calculation method for compensating the current reference of an active power filter, where a nonlinear load exists in a three-phase three-wire asymmetrical voltage system. This new method has been named the extension pq method. The authors have experimented with the extension pq method and the pq method, using the same current controlled IPM inverter for both methods. The results of the experiments proved that in an asymmetrical voltage system, the source current was distorted in the case of the pq method, but was not distorted in the case of the extension pq method
This paper presents harmonic and reactive power compensation based
on a generalized theory of instantaneous reactive power for three-phase
power systems. This new theory gives a generalized definition of
instantaneous reactive power, which is valid for sinusoidal or
nonsinusoidal, balanced or unbalanced, three-phase power systems with or
without zero-sequence currents and/or voltages. The properties and
physical meanings of the newly defined instantaneous reactive power are
discussed in detail. A harmonic and reactive power compensator based on
the new theory for a three-phase harmonic distorted power system with
zero-sequence components in the load current and/or source voltage is
then used as an example to show harmonic and reactive power measurement
and compensation using the new theory. Simulation and experimental
results are presented
A new theory and a conceptual design for the three-phase shunt active power filter (APF) control strategy under imbalanced and distorted supply voltages are presented. Conventionally, the compensation currents injected by the APF are determined according to reference frame transformation-based approaches, where the load instantaneous real and reactive powers are calculated in the new reference frame. The APF injection currents are then computed to maintain the balanced and sinusoidal source currents, as well as the least active power consumption by the APF. However, if current harmonics set by harmonic standards or other constraints are considered, the load harmonic currents after APF compensation can be controlled to meet the requirements. Therefore, the APF may have an adjustable performance. An optimal algorithm for the APF control in steady state is proposed, in which the individual and total harmonic current distortion limits, the minimum load power factor, levels of current imbalance and the size of the APF can be taken into account. The planned APF does not consume or produce active power and only the passive energy-storage elements are required in the new APF design. Results obtained by simulations with Matlab and Simulink show that the proposed approach is more flexible than conventional approaches for compensating reactive power and harmonic/neutral currents of the load, even if the source voltages are severely distorted and imbalanced. The new control strategy is very suitable for planning the APF when several alternative objective functions and constraints are under considerations.
This paper proposes a novel power compensation algorithm in three-phase four-wire systems by using p-q-r theory. The p-q-r theory is compared with two previous instantaneous power theories, p-q theory and cross vector theory. The p-q-r theory provides two-degrees of freedom to control the system currents by only compensating the instantaneous imaginary power without using any energy storage element. The definition of powers maintains power conservation, and agrees well with the general understanding of power. Simulation results show the superiority of p-q-r theory both in definition and compensation.
This paper presents harmonic and reactive power compensation based
on a generalized theory of instantaneous reactive power for three-phase
power systems. This new theory gives a generalized definition of
instantaneous reactive power, which is valid for sinusoidal or
nonsinusoidal and balanced or unbalanced three-phase power systems with
or without zero-sequence currents and/or voltages. The properties and
physical meanings of the newly defined instantaneous reactive power are
discussed in detail. A harmonic and reactive power compensator based on
the new theory for a three-phase harmonic-distorted power system with
zero-sequence components in the load current and/or source voltage is
then used as an example to show harmonic and reactive power measurement
and compensation using the new theory. Simulation and experimental
results are presented
A new, substantial improvement of the hysteresis current control
method for voltage source inverters is presented. A simple and fast
prediction of the hysteresis band is added to a linearized version of
the phase-locked loop control, thus ensuring constant switching
frequency and tight control of the position of modulation pulses. This
allows high accuracy in tracking highly distorted current waveforms and
minimizes the ripple in multiphase systems. The implementation of this
technique is very simple and robust, employing only a small number of
conventional inexpensive analog and logic components. It does not
require trimmings or tunings, giving the control the capability to
adjust itself to the different operating conditions. The proposed method
is compared with the most diffused modulation techniques, demonstrating
its superior performance in responding to the most demanding conditions
met in active filters. The behavior of the method has been fully
verified by simulation and by experimental tests
This paper describes a three-phase four-wire shunt active power
filter using a conventional three-leg converter, without the need of
power supply at DC bus. Two approaches have been developed to control
the active filter. Both control strategies consider harmonics and zero
sequence components in the voltage and current simultaneously. The first
one provides constant power and the second one sinusoidal current to the
source, even under unbalanced voltage conditions. Simulation results
from a complete model of shunt active filter are presented to validate
and compare the control strategies
A new approach is presented for the design of a shunt active
filter in a three-phase, four-wire distribution system with unbalanced,
distorted sources and unbalanced loads. The purpose of the shunt active
filter is to provide compensation currents such that the source needs to
supply balanced (positive-sequence) fundamental source current at unity
power factor even though the load consumes harmonic currents as well as
positive, negative, and zero-sequence currents. A major feature of the
proposed approach is that it does not require symmetrical component
transformation to transform the three-phase voltages and currents to
α-β-o quantities. This makes practical implementation of the
proposed method easier than the symmetrical component transformation
approach. In addition, the power factor of the positive-sequence
fundamental component is close to unity and only positive-sequence power
is supplied by the source. The effectiveness of the proposed control
algorithm is demonstrated by computer simulation and experimental
results of a shunt active filter for a three-phase four-wire
distribution system with distorted, unbalanced source voltages and
unbalanced loads
Conventional active and reactive power theory, valid for the
steady-state analysis is reviewed. The instantaneous power theory,
introduced by H. Akagi et al. (1983, 1984) is also presented. This
instantaneous theory is valid for steady and transient states and for
generic voltage and current waveforms. Some examples explaining the
physical meaning of the new concepts are presented. By using the
concepts of symmetrical components together with the new theory, the
powers in an unbalanced system are analyzed, including the zero-sequence
instantaneous power. An example showing how this theory can be used to
design and control an active power filter is presented. Some simulation
results are presented and discussed
A three-phase voltage-source inverter for a power quality compensator under the unbalanced mains and nonlinear loads is proposed to provide balanced three-phase source current and improve input power factor. The proposed converter is based on the conventional three-phase voltage-source inverter with three additional ac power switches to achieve three-level pulsewidth modulation. The voltage stress of three ac power switches is clamped to half the dc-link voltage. The balanced reference mains currents are estimated using the dc-bus voltage and load currents. A proportional-integral voltage controller is used in the outer loop to compensate the switching losses of the voltage-source inverter. To perform the integrated power quality compensation, a hysteresis current control scheme is adopted to track the balanced line current command in phase with mains voltage. Three voltage levels are generated on the ac terminal of the proposed inverter. Computer simulation and experimental results are provided to verify the effectiveness of the proposed control scheme.
The conventional reactive power in single-phase or three- phase circuits has been defined on the basis of the average value concept for sinusoidal voltage and current waveforms in steady states. The instantaneous reactive power in three-phase circuits is defined on the basis of the instantaneous value concept for arbitrary voltage and current waveforms, including transient states. A new instantaneous reactive power compensator comprising switching devices is proposed which requires practically no energy storage components.
Instantaneous reactive power compen-satorscomprisingswitchingdeviceswithoutenergystorageelements
- H Akagi
- Y Kanazawa
- A Nabae
H. Akagi, Y. Kanazawa, A. Nabae, Instantaneous reactive power compen-satorscomprisingswitchingdeviceswithoutenergystorageelements,IEEE Trans. Ind. Appl. 1A-20 (1984) 625–630.
Activefilterswithcontrolbasedonthep–q theory
- J Afonso
- C Couto
- J Martins
J.Afonso,C.Couto,J.Martins,Activefilterswithcontrolbasedonthep–q theory, IEEE Ind. Electron. Soc. Newslett. 47 (3) (2000) 5–11.
Design and implementation of 3-phase 4-wire shunt active power filter
- M Uçar
Uçar, M., Design and implementation of 3-phase 4-wire shunt active power
filter, Master Thesis, Kocaeli University, Turkey, 2005.