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... phase control of the AC line voltage is one of the well-known methods for power flow control and for transient stability in the flexible AC transmission systems (FACTS) [1]. A phase shifter injects a variable voltage with adequate magnitude and phase to shift the phase angle of transmission line phase voltage, as is shown in Fig. 1 [1] - [8]. The electromechanical or silicon controlled rectifier (SCR) tap-changing transformers are commonly used in conventional realisations of the phase shifters [1], [2]. A regular maintenance of the electromechanical tap changer is needed and, furthermore, both electromechanical and the SCR have relatively slow step response. ...
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... both electromechanical and the SCR have relatively slow step response. Generally, solutions for the phase shifters with or without an energy storage element are proposed. Phase shifters employing one series connected PWM VSI or two parallel and series connected PWM VSI are proposed in [4]. Because of unlimited phase shifting possibilities ( Fig. 1) these topologies can also regulate reactive power in the transmission system. Phase shifting is realized by adding to the original voltage a component in quadrature with this voltage. In three-phase systems, the line voltages are in quadrature with the phase voltages (V bc V a ) and a simple way of obtaining quadrature voltage ...
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... the four-terminal description method and the procedure described in Fig. 10 we obtain equations (17). ...
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... characteristics of magnitude and phase of the voltage transmittance and input power factor obtained by means of (19) -(21) for circuit parameters collected in Table III are shown in Fig. 15 in the next section. For purpose of comparison these characteristics are presented together with ones obtained by means of simulation investigations of the presented circuit with idealized switches and with the experimental test results of the circuit shown in Fig. ...
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... parameters of the investigated circuit shown in Fig. 1 are the same as the ones in theoretical analysis and are given in Table III. The presented results have been obtained for load matching conditions described by (22). In the circuit of the presented phase shifter, the range of change of output voltage is from 0.66 u S to u S (Fig. 15). As is visible from Fig. 16 in the considered ...
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... parameters of the investigated circuit shown in Fig. 1 are the same as the ones in theoretical analysis and are given in Table III. The presented results have been obtained for load matching conditions described by (22). In the circuit of the presented phase shifter, the range of change of output voltage is from 0.66 u S to u S (Fig. 15). As is visible from Fig. 16 in the considered circuit the range of change of phase shift between source and load voltage is from 0 to about ...
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... of the investigated circuit shown in Fig. 1 are the same as the ones in theoretical analysis and are given in Table III. The presented results have been obtained for load matching conditions described by (22). In the circuit of the presented phase shifter, the range of change of output voltage is from 0.66 u S to u S (Fig. 15). As is visible from Fig. 16 in the considered circuit the range of change of phase shift between source and load voltage is from 0 to about ...
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Citations
... The appropriate combination of transformer windings and power electronic converter are able to compensate the changing nature of the load. When the first of the secondary windings of the TR is in "delta" configuration and the second one is in the "star" configuration then the quadrature phase shifter [56] is obtained. The schematic diagram, phasor diagram and experimental time waveforms are presented in Fig. 17. ...
... Taking into account the relation between the voltage phasors shown in for ˚ > 0 |u S1 | = |uL1|, (c) for ˚ < 0 |u S1 | = |uL1|, and (d) for ˚ = 0 |u S1 | < |uL1|. Fig. 17b, the instantaneous values of output voltage are described as [56]: ...
... In the quadrature configuration, the voltage phase shift is correlated with the output voltage boosting (Fig. 17) [56]. In the phase shifter in configuration with HT and matrix converter (Fig. 18a) it is possibility to control the output voltage phase shift without any increase in the magnitude of the output voltage. ...
Power electronics is an integral part of modern energy systems. Moreover, its use adds costs to capital investments in energy systems, along with some reliability issues. Therefore, innovative solutions in power networks require power electronics topologies that are less expensive and more dependable. The use of power electronics without DC energy storage elements (all-silicon solution) is one way to address these issues. This paper provides a comprehensive review of past and present converter topologies without DC energy storage elements which can be employed in novel energy systems. In this paper the converters are divided into two groups: with constant output frequency, and with variable output frequency. The first group includes topologies of matrix and matrix-reactance choppers and their applications in hybrid transformers and power electronic transformers. The second group includes frequency converters based on the matrix converter, covering the conventional, indirect, sparse matrix converter and the matrix-reactance frequency converter. The second part of the article concerns the application of the mentioned converters in the power system functioning as a power interface with AC distributed sources and systems for improving energy quality and the control of power flow in the power network. The sections in this part of the paper present an operational description, and simulation and experimental test results of selected converters and their applications. In the last part of the article there is a brief discussion of current trends, challenges and areas of potential applications and limitations.
... In three-phase systems, the line voltages are in quadrature with the phase voltages (V bc V a ) and a simple way of obtaining quadrature voltage injections is by means of a ∆:Y shunt transformer connected in series to a series transformer (Fig. 14) [35]. The three-phase quadrature phase shifter based on a Hybrid transformer with matrix chopper is described in [36]. In comparison to [35] this solution provides galvanic separation between source and load (Fig. 15). ...
The paper deals with AC voltage transforming circuits applied in power systems. It includes a general description of AC power systems, single and three-phase AC converters, especially PWM AC line choppers and a description of their implementation in AC transmission or distribution systems. This includes a description of the topologies, the operation and test results of the voltage sag/swell compensators, quadrature phase shifters, power flow controllers, static VAr compensators and Interfaces of renewable energy sources
... In the case of AC supply voltage changes, both downward and upward, there is a high risk of damage to devices which are sensitive to voltage changes, and consequently large financial damages may arise, especially in automotive, pharmaceutical and semiconductor industries [2]- [4]. In the literature, there are presented various types of AC/AC voltage sag/swell compensators that mitigate the unwanted effects on supply [5]- [28]. They include: (i) conventional transformer (electromagnetic coupling) with tap changer [5]- [7], (ii) AC/AC thyristor controller [8], (iii) PWM matrix choppers (MC) and PWM matrix reactance choppers (MRC) with or without a series addition transformer, [8]- [14], (iv) AC/DC/AC converters as the dynamic voltage controllers (DVR) with DC storage and a series addition transformer [15]- [22]. ...
This paper deals with a three-phase power system with hybrid transformer (HT). The HT contains a conventional transformer with electromagnetic coupling and PWM AC line chopper integrated with the secondary windings through an electric coupling. The HT uses a three-phase Yy connected transformer with additional secondary windings and three-phase PWM AC line chopper with buck-boost topology. The paper gives a description of the three-phase power system with hybrid transformer (HT) and unsynchronized active load, as well as the mathematical and circuit models of the AC source with HT. The analysis of basic steady state properties of these models are verified by means of the simulation and experimental test results obtained for the power system with HT of about 6 kVA.
... A schematic diagram of the analyzed HT in the D-Q coordinate system is shown in Fig. 9. For steady-state analysis, a single-phase circuit model was divided into four-terminal networks [see Fig. 9(b)] [28], [33]- [37], [39], [40]. The four-terminal networks A a , A F , A b−b , and A L are connected in series and parallel-series with A b . ...
The parameters of electrical energy such as voltage amplitude are very important, particularly from the viewpoint of the final consumer and sensitive loads connected to the grid. The dynamic states in the power grid—deep voltage sags and swells—might cause faults and defects in sensitive loads. This paper deals with a three-phase hybrid transformer (HT) without dc energy storage to compensate voltage sags and swells and to protect sensitive loads against the rapid and extensive changes in supply voltage amplitude. The analyzed HT contains two main units: the first one is the conventional electromagnetic transformer, realizing an electromagnetic coupling, and the second one is the buck–boost matrix-reactance chopper, realizing an electrical coupling in the HT unit. In the presented solution, output voltage is transformed in two ways—electromagnetically and electrically. This paper presents an operational description, the theoretical analysis, and the experimental test results from a 2-kVA laboratory model. On the basis of the authors' research, it can be stated that the HT makes it possible to compensate deep voltage sags (deeper than 50% of nominal source voltage) and overvoltages (up to 140% of nominal source voltage) while maintaining good dynamic properties. The main advantages of the proposed solution, in comparison to other conventional solutions, are the ability to control the output voltage in the range of 0.66–3.5 $U_{S}$, good dynamics (transient state during source voltage $u_{S}$ amplitude change is shorter than 10 ms), and galvanic separation between source and load (such as in the case of the conventional electromagnetic transformer).
This paper proposes a new topology for a three-phase AC/AC converter without DC. The presented topology is based on an direct AC/AC CukB2 bipolar matrix-reactance chopper. The considered solution is intended to control power flow and compensate voltage perturbations in the modern AC power grid with active loads (two-source system). The main difference in the proposed solution in comparison to a conventional UPFC is the lack of DC energy storage in the power electronic converter. The main aim of this paper is to analyse the basic properties of the presented solution in a two-source system and to consider the possibility of bidirectional power flow control. The paper presents an operational description, theoretical analysis and the experimental test results from a 1 kVA laboratory model using a PWM control strategy with open feedback loop.
This paper deals with a three-phase power system with hybrid transformer (HT). The HT contains a conventional three-phase transformer with electromagnetic coupling and AC/AC converter integrated with the secondary windings through an electric coupling. The HT uses a three-phase Yy connected transformer with additional secondary windings and three-phase voltage or current source matrix converter (VSMC or CSMC), which give possibility to changing the value and phase shifting of the output phase voltage. The paper gives a description of such power system with passive load, as well as the modelling and comparison of voltage transfer functions for both solutions of the HT. The steady state analysis results of power systems with simplified HT models are verified by means of the simulation and experimental test results obtained for the power system with HT of about6 kVA.
The paper deals with AC voltage transforming circuits applied in power systems. It includes a general description of AC power systems, single and three-phase AC converters, especially PWM AC line choppers and a description of their implementation in AC transmission or distribution systems. This includes a description of the topologies, the operation and test results of the voltage sag/swell compensators, quadrature phase shifters, power flow controllers, static VAr compensators and interfaces of renewable energy sources.
In this paper is proposed the new topology of AC/AC converter without DC energy storage to compensate deep voltage sags and swells and to control of output voltage phase shift. The proposed solution is intended to protect sensitive loads and energy flow control in AC power grid. The analyzed topology is based on AC/AC ĆukB2 bipolar matrix-reactance chopper. The paper presents an operational description, theoretical analysis and the experimental test results from a 1 kVA laboratory model. The main advantage of the proposed solution, is joining the properties of series AC voltage compensator and phase shifters without DC energy storages. The analyzed converter is ability to compensate single phase voltage interrupt, three-phase 50% voltage sags and swells and change the phase of output voltage in relation to input voltage.
