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The replacement of conventional generation sources by DER creates the need to carefully manage the reactive power maintaining the power system safe operation. The principal trend is to increase the DER volume connected to the distribution network in the coming years. Therefore, the microgrid represents an alternative to offer reactive power management due to excellent controllability features embedded in the DER, which enable effective interaction between the microgrid and the distribution network. This paper proposes a microgrid–iterative reactive power management approach of power-electronic converter based renewable technologies for day-ahead operation. It is designed to be a centralised control based on local measurements, which provides the optimal reactive power dispatch and minimise the total energy losses inside the microgrid and maintain the voltage profile within operational limits. The proposed optimal-centralised control is contrasted against seven local reactive power controls using a techno-economic approach considering the steady–state voltage profile, the energy losses, and the reactive power costs as performance metrics. Three different reactive power pricing are proposed. The numerical results demonstrate the optimal microgrid–interactive reactive power management is the most suitable techno-economic reactive power control for the day–ahead operation.

Investment on generation system and transmission network is an important issue in power systems, and investment reversibility closely depends on performing an optimal planning. In this regard, generation expansion planning (GEP) and transmission expansion planning (TEP) have been presented by researchers to manage an optimal planning on generation and transmission systems. In recent years, a large number of research works have been carried out on GEP and TEP. These problems have been investigated with different views, methods, constraints and objectives. The evaluation of researches in these fields and categorising their different aspects are necessary to manage further works. This study presents a comprehensive review of GEP and TEP problems from different aspects and views such as modelling, solving methods, reliability, distributed generation, electricity market, uncertainties, line congestion, reactive power planning, demand-side management and so on. The review results provide a comprehensive background to find out further ideas in these fields.

As high amounts of new energy and electric vehicle (EV) charging stations are connected to the distribution network, the voltage deviations are likely to occur, which will further affect the power quality. It is challenging to manage high quality voltage control of a distribution network only relying on the traditional reactive power control mode. If the reactive power regulation potentials of new energy and EVs can be tapped, it will greatly reduce the reactive power optimization pressure on the network. Keeping this in mind, our reasearch first adds EVs to the traditional distribution network model with new forms of energy, and then a multi-objective optimization model, with achieving the lowest line loss, voltage deviation, and the highest static voltage stability margin as its objectives, is constructed. Meanwihile, the corresponding model parameters are set under different climate and equipment conditions. Ultimately, the optimization model under specific scenarios is obtained. Furthermore, considering the supply and demand relationship of the network, an improved technique for order preference by similarity to an ideal solution decision method is proposed, which aims to judge the adaptability of different algorithms to the optimized model, so as to select a most suitable algorithm for the problem. Finally, a comparison is made between the constructed model and a model without new energy. The results reveal that the constructed model can provide a high quality reactive power regulation strategy.

Optimal Reactive Power Dispatch (ORPD is thought of as a noncontinuous, nonlinear global optimization problem. Within the system’s constraints, the ORPD manages to accomplish the reactive power flow. Due to its more intricate linkage of variables, the reactive power issue is more challenging to resolve than the optimum power flow issue. With the existence of renewable energy resources (RERs), solving the ORPD problem to attain the most stable and secure system condition has become a more challenging task. The goal of this article is to solve the objective function of ORPD combined with RERs using a metaheuristic novel optimizer named the African Vultures Optimization Algorithm abbreviated by (AVOA), where the formulation of the ORPD issue including minimization of three single objective functions as follows, voltage deviation, system operating cost, and real power loss, is introduced and also transmission power loss minimization is embraced with the simultaneous incorporation of the optimal renewable energy resources (RERs). Where the ORPD problem complexity grows exponentially with a mixture of continuous and discrete control variables, two distinct continuous and discrete types of optimization variables are considered, and the proposed single objective functions that meet different operating constraints are then transformed into a coefficient multi-objective ORPD problem and elucidated using the weighted sum approach. To validate the suggested algorithm’s effectiveness in addressing the ORPD issue, it is evaluated on three standard IEEE networks: the IEEE-30 bus small-scale network, the IEEE-57 bus medium-scale network, and the IEEE-118 bus large-scale network using different scenarios and the outcomes are compared to these other popular optimization techniques. The findings show that the suggested AVOA algorithm provides an efficient and sturdy high-quality solution for tackling ORPD situations and vastly enhances the overall system performance of power at all scales.

Virtual synchronous generator (VSG) has been widely researched and applied to converters for their grid‐forming capabilities. However, the intrinsic coupling between the active and reactive power outputs of VSGs negatively impacts the power quality delivered to the grid, particularly in microgrids. When VSG is compensating for the reactive power imbalances, the active power output will concurrently change, leading to a variation of frequency. Although existing literature proposes various improvements to decouple these power outputs, complete decoupling cannot be achieved solely by VSGs. This letter analyses the coupling mechanism and investigates a hybrid approach combining a VSG and a synchronous condenser (SC) to mitigate this effect, improving the power quality. Additionally, this study modifies the traditional reactive power control of VSGs to ensure voltage stability during transients. Test cases are carried out to verify the effectiveness of the proposed method. The results show that the system active and reactive power are effectively decoupled, and it maintains the frequency while regulating the grid voltage. This letter analyses the coupling mechanism and investigates a hybrid approach combining a virtual synchronous generator (VSG) and a synchronous condenser to mitigate this effect, improving the power quality. Additionally, this study modifies the traditional reactive power control of VSGs to ensure voltage stability during transients.

Despite global warming, renewable energy has gained much interest worldwide due to its ability to generate large-scale energy without emitting greenhouse gases. The availability and low cost of wind energy and its high efficiency and technological advancements make it one of the most promising renewable energy sources. Hence, capturing large amounts of wind energy is essential today. The large-scale integration of wind power sources must be evaluated and mitigated to develop a sustainable future power system. Wind energy research and the government are working together to overcome the potential barriers associated with its penetration into the power grid. This paper reviews the social, environmental, and cost-economic impacts of installing large-scale wind energy plants. A valuable review of wind energy technology and its challenges is also presented in this paper, including the effects of wind farms on nearby communities, generation uncertainty, power quality issues, angular and voltage stability, reactive power support, and fault ride-through capability. Besides, socioeconomic, environmental, and electricity market challenges due to the grid integration of wind power are also investigated. Finally, potential technical challenges to integrating large-scale wind energy into the power grid are reviewed regarding current research and their available mitigation techniques.

In power grid modernisation, optimal network use is essential to preserving acceptable voltage profiles, boosting voltage stability, reducing power losses, and strengthening system security and dependability. This can be accomplished by strategically placing reactive power compensation devices within transmission and distribution networks, such as capacitor banks, synchronous condensers, flexible alternating current transmission system (FACTS) devices and custom power devices. The optimal location and size of these devices are essential for effective investment, but previous research has mostly concentrated on a variety of methods for this goal, using different indices to evaluate power loss, voltage stability, voltage profile and line loadability. Despite these initiatives, there is still a lack of a thorough analysis of how current indices and methodologies are applied to all varieties of reactive power compensation devices. This paper offers a detailed literature review on the ideal placement and sizing of these devices, encompassing analytical, conventional and hybrid-based techniques. It discusses key objectives such as power loss reduction, voltage deviation (VD) mitigation, voltage stability enhancement and improvements in system reliability and security. Additionally, the paper examines the relevance of reactive power for stakeholders, including transmission system operators (TSOs), distribution system operators (DSOs) and power generating companies, and explores the mathematical modelling of optimal reactive power dispatch (ORPD), considering the impact of renewable energy sources (RESs) and the role of FACTS devices.

The design of reliable power filters that mitigate current and voltage harmonics to meet the power quality requirements of the utility grid is a major requirement of present-day power systems. In this paper, a detailed systematic approach to design a shunt active power filter (SAPF) for power quality enhancement is discussed. A proportional–integral (PI) controller is adopted to regulate the DC-link voltage. The instantaneous reactive power theory is employed for the reference current’s extraction. Hysteresis current control is used to obtain the gate pulses that control the voltage source inverter (VSI) switches. The detailed SAPF is developed and simulated for balanced nonlinear loads and unbalanced nonlinear loads using MATLAB/Simulink. The simulation results indicate that the proposed filter can minimize the harmonic distortion to a level below that deployed by the Institute of Electrical and Electronics Engineers (IEEE) standards.

This paper presents a groundbreaking power distribution technique that focuses on the loss rate of individual wind turbines. Distinct from conventional methods, our strategy prioritizes seamless integration and adaptability within wind farm management systems. By evaluating power losses in specific branches of a wind farm, our approach enhances overall performance by strategically allocating reactive power to reduce cumulative losses. When compared to traditional uniform distribution and Particle Swarm Optimization (PSO) methods, our innovative approach stands out for its superior efficiency and adaptability. Comprehensive simulations underline the strengths and weaknesses of prevailing methods and underscore the superior efficacy of our proposed technique.

Harmonics is a widespread phenomenon in power system. With the rapid development of new energy generation, it is more urgent to monitor and suppress harmonics in power system. Considering the accuracy and real-time of harmonic detection, a novel harmonic detection method based on FFT and instantaneous reactive power theory is proposed. In this method, the harmonic frequency of the signal to be measured is first determined by windowed FFT, and then the harmonic amplitude and phase are calculated by an improved harmonic detection method based on instantaneous reactive power theory. The example results show that the proposed method has high detection accuracy and good real-time performance, and it can realize the fast detection of harmonics.