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Increasing large-scale integration of renewable in conventional power system has led to an increase in reserve power requirement owing to the forecasting error. Innovative operating strategies are required for maintaining balance between load and generation in real time, while keeping the reserve power requirement at its minimum. This research work...
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... study developed a simplified aggregated WPP model based on the IEC 61400-27-1 recommendations [30]. The developed generic WPP model as shown in Figure 4 has been further simplified for the purpose of primary and secondary active power control. The aggregated WPP model had a hierarchical control level, i.e., active power was controlled at the WPP level and at the wind turbine level. ...
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Distributed generation (DG) has gained popularity among electricity end users who are determined to contribute to a cleaner environment by conforming to green and sustainable energy sources for various daily needs. The power system impact of such trends (e.g. roof-top solar-PV) need thorough investigation, such as impact on fault current levels on...
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... The inclusion of flexible loads in power systems offers valuable demand response capabilities, allowing for effective management during peak hours and optimizing power flow within existing grids. Consequently, this not only diminishes the requirement for reserve resources but also fosters the steady operation of the system without entailing any supplementary expenditures [3], [4]. By responding to fluctuations in demand, flexible loads help to mitigate imbalances between load and generation caused by uncertainties in probabilistic load or wind forecasting. ...
Integrating flexible load within modern power systems substantially benefits grid management, resource optimization , and system efficiency. By harnessing the capabilities of flexible load, power system operators can effectively address challenges arising from intermittent renewable energy sources and unpredictable fluctuations in electricity consumption. This research presents an innovative approach to mitigate issues related to wind power forecasting errors in power systems with high wind energy integration. The proposed solution involves integrating flexible load potential within the Load Frequency Control (LFC) scheme, enabling efficient management of grid power imbalances. To evaluate the effectiveness of this approach, a comprehensive simulation study is conducted using the DigSI-LENT Power Factory software. The simulation model combines thermal, gas turbine, and wind energy systems with a dynamic flexible load model integrated into the LFC operation. This enhances active power balance regulation, reduces dependency on traditional generators, and boosts economic efficiency.
... The intermittent nature of wind power introduces uncertainty, thereby necessitating a substantial increase in the usage of operating reserves to maintain an equilibrium in active power within the system. [3,4] integrated massive wind power into traditional power grids by sourcing the requisite reserves from thermal power plants. However, this approach severely impacted the system's operational cost. ...
The modern power system heavily depends on wind energy. Yet, intermittent wind energy poses challenges for system operators due to forecasting inaccuracies that require extra balancing power to keep the frequency stable. Conventional power plants offer these services but are expensive and environmentally harmful. The modern power system aims to maximize wind power integration, replacing traditional plants and their benefits. Thus, alternative control and balancing solutions must be explored, like tapping into regulation reserves from electric vehicles (EVs) without affecting their normal functions. This study suggests an optimized dispatch strategy for automatic generation control (AGC) that leverages the storage capability of EVs to balance the grid's active power. The strategy enables AGC to utilize EVs while considering their operational limitations effectively. Simulations using DIgSILENT software were conducted to assess the performance of the proposed strategy. The results demonstrate that integrating EVs with thermal power plants efficiently reduces real-time power imbalances due to massive wind energy penetration and improves power system security.
... An alternative to energy storage comes in the form of making conventional power plants more flexible [34,35], but most Polish power plants are old (more than 30 years of age). ...
With the increasing share of renewable sources in the energy mix, there is a need to balance energy production from weather-dependent sources, such as wind turbines and photovoltaics. This is also a current global trend associated with climate policy. In Poland, there has been a significant increase in energy production from renewable sources, leading to a duck curve phenomenon mainly in the case of photovoltaics, which requires balancing this production through various measures. One possible way to achieve this is energy storage installation. This article identifies the need for energy storage to ensure the stability of electricity production from low-flexibility sources like coal-based power plants. For this purpose, a methodology has been developed to determine the daily minimum energy storage capacities which would also allow for the integration of other stable (though less flexible) energy sources, such as nuclear power. In the case of Poland, energy storage has been estimated to require, as a median value, approximately 6 GWh of additional storage capacity, which is equivalent to twice the planned capacity of the Młoty Pumped Storage Power Plant.
... This technique is often utilized when wind speeds are relatively stable across the wind farm and can also control power output from each turbine [6]. These regulatory measures affect the quantity of wind energy extracted and can be utilized to regulate the grid frequency [17,18]. ...
... Determining the reference signal involves multiple inputs, encompassing the existing wind power, AGC set point, grid measure power, and real-time feedback signal of each wind turbine. The feedback signal yields instantaneous data about wind turbine functionality, which is then utilized to establish the reference signal, thereby achieving optimal frequency support [17]. Figure 2 presents a wind farm considering the dynamic features required to provide ancillary services, specifically primary and secondary control through wind turbines' AGC [20]. ...
... It also covers the challenges faced during the integration process and how they were overcome. Basit proposed a realtime dynamic dispatch control strategy for AGC in [17] that employs cold storage units to achieve power balancing in large-scale wind-integrated grids. It is shown that integrating cold storage units into AGC services can ultimately improve grid flexibility, reduce peak demand and electricity costs, and enhance grid resilience. ...
With the increasing integration of wind energy sources into conventional power systems, the demand for reserve power has risen due to associated forecasting errors. Consequently, developing innovative operating strategies for automatic generation control (AGC) has become crucial. These strategies ensure a real-time balance between load and generation while minimizing the reliance on operating reserves from conventional power plant units. Wind farms exhibit a strong interest in participating in AGC operations, especially when AGC is organized into different regulation areas encompassing various generation units. Further, the integration of flexible loads, such as electric vehicles and thermostatically controlled loads, is considered indispensable in modern power systems, which can have the capability to offer ancillary services to the grid through the AGC systems. This study initially presents the fundamental concepts of wind power plants and flexible load units, highlighting their significant contribution to load frequency control (LFC) as an important aspect of AGC. Subsequently, a real-time dynamic dispatch strategy for the AGC model is proposed, integrating reserve power from wind farms and flexible load units. For simulations, a future Pakistan power system model is developed using Dig SILENT Power Factory software (2020 SP3), and the obtained results are presented. The results demonstrate that wind farms and flexible loads can effectively contribute to power-balancing operations. However, given its cost-effectiveness, wind power should be operated at maximum capacity and only be utilized when there is a need to reduce power generation. Additionally, integrating reserves from these sources ensures power system security, reduces dependence on conventional sources, and enhances economic efficiency.
... Figure 4 shows frequency fluctuation as a result of an increasing number of EV batteries in the FCS. Frequency fluctuation happens at the PCC because grid frequency deviates from its rated value due to the increased power exchange between the various EV batteries and the charging station, which also results in corresponding voltage sags at the PCC, as shown in Figure 5 [30]. Voltage sags occur when multiple Evs are applied at the FCS due to the EV load variation, causing a voltage reduction of 10% or more from its nominal value, which lasts between 0.5 cycles to one minute [31]. ...
... Voltage sags occur when multiple Evs are applied at the FCS due to the EV load variation, causing a voltage reduction of 10% or more from its nominal value, which lasts between 0.5 cycles to one minute [31]. For a rectifier converter, any increase in the FCS load to the grid will cause a significant frequency disturbance to the power grid [30,31]. Therefore, this will require a higher initial grid stability reinforcement to ensure that the frequency setpoint is maintained. ...
... These controllers are utilized to allow pre- Figure 5. Voltage sags at PCC as number of FCS loads increases [31]. For a rectifier converter, any increase in the FCS load to the grid will cause a significant frequency disturbance to the power grid [30,31]. Therefore, this will require a higher initial grid stability reinforcement to ensure that the frequency setpoint is maintained. ...
The growing trend for electric vehicles (EVs) and fast-charging stations (FCSs) will cause the overloading of grids due to the high current injection from FCSs’ converters. The insensitive nature of the state of charge (SOC) of EV batteries during FCS operation often results in grid instability problems, such as voltage and frequency deviation at the point of common coupling (PCC). Therefore, many researchers have focused on two-stage converter control (TSCC) and single-stage converter (SSC) control for FCS stability enhancement, and suggested that SSC architectures are superior in performance, unlike the TSCC methods. However, only a few research works have focused on SSC techniques, despite the techniques’ ability to provide inertia and damping support through the virtual synchronous machine (VSM) strategy due to power decoupling and dynamic response problems. TSCC methods deploy current or voltage control for controlling EVs’ SOC battery charging through proportional-integral (PI), proportional-resonant (PR), deadbeat or proportional-integral-derivative (PID) controllers, but these are relegated by high current harmonics, frequency fluctuation and switching losses due to transient switching. This paper reviewed the linkage between the latest research contributions, issues associated with TSCC and SSC techniques, and the performance evaluation of the techniques, and subsequently identified the research gaps and proposed SSC control with SOC consideration for further research studies.
... The power system planners employ various scheduling mechanisms to deploy the extra amount of reserve, keeping the power grids in a balance condition. Conventionally, the additional reserves are provided manually or through automatic generation control (AGC) considering only the economic operation in the account [2]. As The aforementioned literature has tackled the overloading problem in a detailed manner. ...
Modern power systems are largely based on renewable energy sources, especially wind power. However, wind power, due to its intermittent nature and associated forecasting errors, requires an additional amount of balancing power provided through the automatic generation control (AGC) system. In normal operation, AGC dispatch is based on the fixed participation factor taking into account only the economic operation of generating units. However, large-scale injection of additional reserves results in large fluctuations of line power flows, which may overload the line and subsequently reduce the system security if AGC follows the fixed participation factor’s criteria. Therefore, to prevent the transmission line overloading, a dynamic dispatch strategy is required for the AGC system considering the capacities of the transmission lines along with the economic operation of generating units. This paper proposes a real-time dynamic AGC dispatch strategy, which protects the transmission line from overloading during the power dispatch process in an active power balancing operation. The proposed method optimizes the control of the AGC dispatch order to prevent power overflows in the transmission lines, which is achieved by considering how the output change of each generating unit affects the power flow in the associated bus system. Simulations are performed in Dig SILENT software by developing a 5 machine 8 bus Pakistan’s power system model integrating thermal power plant units, gas turbines, and wind power plant systems. Results show that the proposed AGC design efficiently avoids the transmission line congestions in highly wind-integrated power along with the economic operation of generating units.
... However, renewable electricity generation depends on the immediate availability of renewable energy resources (O'Connell, Reynders, and Keane 2021). For example, the variability of wind energy is significant even when considering large geographical areas (Basit et al. 2019). ...
The management of energy systems with a high share of renewables is a challenge for grid planners and operators, as weather and energy demand do not always coincide. Investigating the energy autonomy of cities and their local energy resources can help to overcome this challenge. To this end, real energy demand data from the city of Loja, Ecuador, and wind energy generation from a nearby wind farm were compared. This showed that wind energy provides 53% of the city’s demand. It is exposed that despite the excess energy, the wind farm’s ability to supply the city with electricity is limited to about 74% when the wind farm is expanded to twice its rated capacity. The results show that in order to improve the autonomy, other energy sources, such as photovoltaic, as well as useful size energy storage are needed.
... The results demonstrated the ability of DR control loop for LFC performance in the SG perspective. An active power balance control strategy that stressed the integration of flexible loads and wind energy in AGC is suggested in [112]. The study revealed that the incorporation of flexible loads and wind power into the AGC system can eradicate the fluctuations via provisioning of active power support to the real-time imbalances. ...
Automatic generation control (AGC) is primarily responsible for ensuring the smooth and efficient operation of an electric power system. The main goal of AGC is to keep the operating frequency under prescribed limits and maintain the interchange power at the intended level. Therefore , an AGC system must be supplemented with modern and intelligent control techniques to provide adequate power supply. This paper provides a comprehensive overview of various AGC models in diverse configurations of the power system. Initially, the history of power system AGC models is explored and the basic operation of AGC in a multi-area interconnected power system is presented. An in-depth analysis of various control methods used to mitigate the AGC issues is provided. Application of fast-acting energy storage devices, high voltage direct current (HVDC) inter-connections, and flexible AC transmission systems (FACTS) devices in the AGC systems are investigated. Furthermore, AGC systems employed in different renewable energy generation systems are overviewed and are summarized in tabulated form. AGC techniques in different configurations of microgrid and smart grid are also presented in detail. A thorough overview of various AGC issues in a deregulated power system is provided by considering the different contract scenarios. Moreover, AGC systems with an additional objective of economic dispatch is investigated and an overview of worldwide AGC practices is provided. Finally, the paper concludes with an emphasis on the prospective study in the field of AGC.
... In power systems, the whole energy production within a period of time should be always equal to the whole energy consumption, whether consumed in loads or lost in carrier assets like transmission lines [1]. In any conditions that this balance is not met for a while, the system would face security challenges or even collapse [2,3]. ...
The integration of more renewable energy resources into distribution networks makes the operation of these systems more challenging compared to the traditional passive networks. This is mainly due to the intermittent behavior of most renewable resources such as solar and wind generation. There are many different solutions being developed to make systems flexible such as energy storage or demand response. In the context of demand response, a key factor is to estimate the amount of load over time properly to better manage the demand side. There are many different forecasting methods, but the most accurate solutions are mainly found for the prediction of aggregated loads at the substation or building levels. However, more effective demand response from the residential side requires prediction of energy consumption at every single household level. The accuracy of forecasting loads at this level is often lower with the existing methods as the volatility of single residential loads is very high. In this paper, we present a hybrid method based on time series image encoding techniques and a convolutional neural network. The results of the forecasting of a real residential customer using different encoding techniques are compared with some other existing forecasting methods including SVM, ANN, and CNN. Without CNN, the lowest mean absolute percentage of error (MAPE) for a 15 min forecast is above 20%, while with existing CNN, directly applied to time series, an MAPE of around 18% could be achieved. We find the best image encoding technique for time series, which could result in higher accuracy of forecasting using CNN, an MAPE of around 12%.
