Reactive Power Control Research Articles

Development of a prototype to evaluate and monitor energy efficiency aiming at power quality 4.0

In research and development projects, the need to implement prototypes to speed up the development and delivery process is paramount, offering tools to validate scenarios and anticipate challenges. The aim of this research is to experimentally develop a prototype for monitoring electrical power systems using a gateway that converts MODBUS-RTU communication protocols to TCP, providing useful information for technicians and managers of a company in the Manaus Industrial Estate (PIM) in the field of reflective tapes. To achieve this goal, it was necessary to specify the technical requirements for panel assembly and communication via MODBUS, acquire and research materials in accordance with the technical specifications and technological requirements, implement the monitoring system with an IMS Controller for reactive power compensation, and configure and parameterise the MODBUS protocol via the RTU to TCP converter. The prototype is expected to be able to take accurate measurements and, in the data acquisition process, obtain readings of electrical quantities such as: voltage per phase; current per phase; power factor per phase; active power per phase; reactive power per phase; apparent power per phase; frequency; voltage THD and voltage harmonics. The prototype must act intelligently to drive the capacitor bank to control and monitor reactive power. The development of the prototype included crucial stages such as the specification of technical requirements, the acquisition of suitable materials, and the implementation and configuration of the system. The specification ensured that the components were aligned with the project objectives, while the procurement of materials ensured the quality and efficiency of the system. The implementation of the Automatic Reactive Power Compensation Controller was vital for reactive power compensation and the configuration of the MODBUS protocol ensured precise communication between the components. To summarise, this project demonstrates the importance of prototypes in technological advancement, offering practical and efficient solutions for industry. The prototype developed to monitor electrical power systems through a MODBUS-RTU to TCP protocol converter gateway represents a significant advance, providing essential data and contributing to informed decision-making, improving the performance and management of the company's energy resources.

Design and Implementation of Crowbar and STATCOM for Enhanced Stability of Grid-Tied Doubly Fed Induction Wind Generators

These days, one of the most used layouts in the wind power industry is a variable-speed doubly-fed induction wind generator (DFIWG). For providing active power (P) and reactive power (Q) control during grid failures, this research examines the DFIWG. The system's transient behavior is examined under normal and abnormal circumstances. Through control of rotor side (RSC) and grid side (GSC) converters, Q assistance for the grid, and power converter stress reduction, the suggested control approach achieves system stability while enabling DFIWG to operate smoothly during grid failures. The DFIWG is exposed to three- and two-phase faults to analyze the machine's performance. The crowbar and STATCOM tools are implemented to enhance the system performance under faults and compared with the base case. The implemented tools successfully suppress rotor and stator overcurrent, over voltage at the DC link (DCL), and power oscillations, as well as supporting the grid voltage understudied cases. The obtained results prove that both STATCOM and crowbar not only enhance the system's effectiveness and performance but also enable the system to achieve the fault ride-through capacity (FRTC). MATLAB/SIMULINK 2017b is used for time-domain computer simulations.

Novel Reactive Power Control Strategy for Mitigating Voltage Rise in the Malaysian Low Voltage Distribution Network with High PV Penetration

Novel Reactive Power Control Strategy for Mitigating Voltage Rise in the Malaysian Low Voltage Distribution Network with High PV Penetration

SUIVI DE LA QUALITÉ DE PUISSANCE MAXIMALE D'UN GÉNÉRATEUR D'INDUCTION À DOUBLE ALIMENTATION BASÉ SUR UN CONTRÔLEUR DE RÉSEAU NEURONAL ARTIFICIEL POUR SYSTÈME DE CONVERSION D'ÉNERGIE ÉOLIENNE

Renewable energy sources are playing a crucial role in satisfying the upcoming energy source needs for the world. The current power system is power electronics converter based, with several non-linear loads and spotted generations of renewable energy sources, resulting in many power quality issues. Most existing research analyzed MATLAB simulations and presented a high Total Harmonics Distortion (THD) level. This research work proposed an artificial neural network (ANN) control technique for a doubly fed induction generator (DFIG) based wind energy conversion systems (WECSs). To decrease chattering phenomena during the excitation arrangement, an advanced controller works for adaptive modification of the irregular power gain, even preserving the strength of the closed-loop scheme. The proposed PI controller one step forward improves reliability and tracks maximum voltage from the pulse width modulation rectifier. At primary, the modeling of the DFIG was presented. Then, using the proposed ANN controller, the rotor magnitude was tuned to recognize vector control of active and reactive power. The converter intends to activate at unity power factor and provide input currents with adequate harmonic content. The interface between the power’s electronic converter and the DFIG pulls out the most real power potential. The proposed prototype hardware model and simulation results are verified.

Research on Voltage Coordinated and Stability Control of Condensers Based on Reactive Power Replacement

Abstract In this research, we investigated condenser voltage coordination and stability control systems by analyzing voltage coordinated control mode among excitation, voltage coordination and stability as well as automatic-voltage reactive power control systems. By using dynamic excitation regulation and steady-state regional voltage source control replacement, dynamic reactive power quickly output under fault condition as well as optimized regional reactive power under steady state were realized. The correctness and practicability of the proposed strategy was verified through engineering application. Adopting the reactive power displacement of voltage coordination control system to solve local voltage instability problem after UHV DC blocking. The proposed method realized multi-time scale emergency, recovery and steady-state control of the system under steady and dynamic states.

Research on continuous commutation failure suppression strategy for multi-feed DC transmission system considering harmonic characteristic factors

Abstract Regarding the sustained issues of commutation failures in the hybrid double-fed DC system encompassing Line Commutated Converter High Voltage Direct Current (LCC-HVDC) and Modular Multilevel Converter High Voltage Direct Current (MMC-HVDC, from the perspective of harmonics, the harmonics in the voltage waveform of the AC bus on the inverter side are analyzed. Besides, a commutation failure suppression strategy for the hybrid doubly-fed DC transmission system based on the minimum shutdown area is designed, in which the setting value of the shutdown angle of the harmonic is considered in the minimum shutdown area. The reactive power is obtained by attaching the setting value to the reactive power control link of MMC-HVDC, and the simulation analysis in PSCAD verifies that the strategy can make the MMC-HVDC output more reactive power during the fault in the weak AC system. Increasing the shut-off margin of the manifold reduces the potential for continuous commutation failures in LCC-HVDC.

An Efficient DC-AC Power Integration Model for Single-Phase Systems, Simulated in MATLAB

In the face of growing clean energy demands, this study presents a model for integrating Direct Current (DC) sources into the existing Alternating Current (AC) grid. The model is based on a single-phase system where a DC source is added. A converter, designed using the synchronous reference frame, is proposed to address integration issues. This converter allows for the control of both active and reactive power using a dq reference frame. A Proportional-Integrator (PI) controller is chosen for this purpose. To generate the necessary operational references, a Phase-Locked Loop (PLL) is used. An LCL filter is also incorporated based on its performance quality. The entire model is simulated in MATLAB, and the output obtained confirms the model’s ability to control both active and reactive power when integrating DC with AC and T. This work significantly contributes to the efforts of integrating clean energy into our existing grid systems.

Reliability indices improvement according to grid code compliance applied to PV power plants (Algerian grid code case study)

Abstract The reliability of any electrical power system must be evaluated in order to increase durability. In accordance with the IEEE standard 1366, 2012, reliability is modeled by quality of service and profitability indices. This reliability highly depends on the applied grid code. An investigation was conducted on data recorded during these last five years since 2018 from OUED KEBRIT PV power plant located in Algeria. It was highlighted in this paper that the inverter power controller can decrease significantly the reliability. In many cases electrical protections of PV power plant react by disconnecting it, whereas the fault is outside. Data mining shows that many PV power plant breakdowns are not necessary. A modified active and reactive power control strategy was applied to the PV power plant and compared to the existing one. The proposal is based on software and hardware management. Thanks to the proposed strategy control, the PV power plant decoupled control is more reliable and was highly improved in this paper.

Research on reactive voltage control strategy for substations connected to photovoltaic systems

Abstract The reactive voltage control of conventional substations is mainly realized by adjusting the switching of capacitors or reactors and changing the transformer ratio, which can only be controlled discretely. The PV inverter can carry out continuous reactive power control, and the reactive voltage control strategy of the conventional substation does not consider the reactive power control of the PV. In this paper, the nine-zone diagram control strategy of the traditional substation is used as a reference, and the reactive voltage optimization control strategy of a substation with a photovoltaic power generation system is constructed considering the characteristics that photovoltaic inverter can continuously regulate reactive power. Taking the internal power grid of an enterprise as an example, the simulation analysis verifies the effectiveness of the control strategy, which can ensure that the voltage and power factor of the grid-connected access point are qualified. At the same time, the voltage fluctuation of the grid-connected point can be reduced, and the network consumption can be reduced.

Transient AC Overvoltage Suppression Orientated Reactive Power Control of the Wind Turbine in the LCC-HVDC Sending Grid

Transient AC Overvoltage Suppression Orientated Reactive Power Control of the Wind Turbine in the LCC-HVDC Sending Grid

Distributed Cooperative Reactive Power Control of PV Systems With Dynamic Leader

Distributed Cooperative Reactive Power Control of PV Systems With Dynamic Leader

Adaptive reactive power control strategy for grid-forming inverter under symmetrical fault

Abstract Due to the inability of the grid-type control method to compensate for the comprehensive reduction in system inertia, strength, and short-circuit capacity caused by the proportional decrease of synchronous machines, the power grid exhibits insufficient resistance to disturbances, leading to severe stability risks in terms of rotor angle, frequency, and voltage. In response to these challenges, grid-forming inverters have emerged. Under symmetrical faults, the low-voltage ride-through of grid-forming inverters is often accompanied by a frozen reactive power environment, resulting in a direct output of increased voltage and reactive current. However, an elevated reactive power command can cause a sharp increase in the potential amplitude within grid-forming inverters. After the grid fault is cleared, the excessively high internal potential can cause a short-term and rapid increase in terminal voltage, potentially leading to overvoltage, which is detrimental to the operation of grid-connected devices. To address this issue, this paper first employs a grid-forming inverter controlled by a virtual synchronous machine control method. Using the grid positive-sequence voltage as a reference value, it identifies whether a voltage drop fault has occurred. Based on this, an adaptive reactive power control strategy is proposed, which can promptly achieve the same effect as the frozen reactive power environment during faults, while also promptly restoring the reactive power environment after fault clearance, thereby avoiding overvoltage issues. The feasibility of the proposed method is verified through the establishment of a simulation system.

Adaptive Semiconductor Reactive Power Controllers with High-Quality Reactive Current for 0.4-kV Networks

Adaptive Semiconductor Reactive Power Controllers with High-Quality Reactive Current for 0.4-kV Networks

Secondary Control Strategies in the DC Microgrids

Now, DC microgrids have become more popular for several reasons, including the lack of issues related to reactive power and frequency control, the direct integration of energy storage devices and solar photovoltaic, and the higher utilization of DC loads. A DC microgrid using several sources (distributed generation) is a popular research area. The main issue in such a DC microgrid is to provide good voltage regulation and proportional power sharing among all sources. Control strategy is very important to solve the above issue in order to maintain the reliability and stability of DC microgrids. Hence, a comprehensive review of DC microgrid control techniques is essential. Compared to other methods, hierarchical control is widely used to solve the aforementioned issue. It consists of three layers of control: primary control, secondary control, and tertiary control. At the primary level, to improve current sharing performance, droop control is usually applied. Secondary control is used for voltage regulation of the DC bus. A tertiary control is a higher-level control to achieve Optimization and economical grid operation. In traditional primary control, it is not possible to attain accurate power sharing and voltage regulation simultaneously. Thus, secondary control is required. So, this paper reviews the secondary level control techniques in the hierarchical control strategy for DC microgrids. Precisely, Centralized, distributed, and decentralized approach-based secondary control are reviewed. Several secondary control techniques have been thoroughly examined in terms of their advantages and disadvantages making this an excellent resource for both academics and business executives.

Volt-VAR Control in Active Distribution Networks Using Multi-Agent Reinforcement Learning

With the advancement of power systems, the integration of a substantial portion of renewable energy often leads to frequent voltage surges and increased fluctuations in distribution networks (DNs), significantly affecting the safety of DNs. Active distribution networks (ADNs) can address voltage issues arising from a high proportion of renewable energy by regulating distributed controllable resources. However, the conventional mathematical optimization-based approach to voltage reactive power control has certain limitations. It heavily depends on precise DN parameters, and its online implementation requires iterative solutions, resulting in prolonged computation time. In this study, we propose a Volt-VAR control (VVC) framework in ADNs based on multi-agent reinforcement learning (MARL). To simplify the control of photovoltaic (PV) inverters, the ADNs are initially divided into several distributed autonomous sub-networks based on the electrical distance of reactive voltage sensitivity. Subsequently, the Multi-Agent Soft Actor-Critic (MASAC) algorithm is employed to address the partitioned cooperative voltage control problem. During online deployment, the agents execute distributed cooperative control based on local observations. Comparative tests involving various methods are conducted on IEEE 33-bus and IEEE 141-bus medium-voltage DNs. The results demonstrate the effectiveness and versatility of this method in managing voltage fluctuations and mitigating reactive power loss.

Development of Grid-Forming and Grid-Following Inverter Control in Microgrid Network Ensuring Grid Stability and Frequency Response

This paper proposes a control strategy for grid-following inverter control and grid-forming inverter control developed for a Solar Photovoltaic (PV)–battery-integrated microgrid network. A grid-following (GFL) inverter with real and reactive power control in a solar PV-fed system is developed; it uses a Phase Lock Loop (PLL) to track the phase angle of the voltages at the PCC and adopts a vector control strategy to adjust the active and reactive currents that are injected into the power grid. The drawback of a GFL inverter is that it lacks the capability to operate independently when the utility grid is down due to outages or disturbances. The proposed grid-forming (GFM) inverter control with a virtual synchronous machine provides inertia to the grid, generates a stable grid-like voltage and frequency and enables the integration of the grid. The proposed system incorporates a battery energy storage system (BESS) which has inherent energy storage capability and is independent of geographical areas. The GFM control includes voltage and frequency control, enhanced islanding and black start capability and the maintenance of the stability of the grid-integrated system. The proposed model is validated under varying irradiance conditions, load switching, grid outages and temporary faults with fault ride-through (FRT) capability, and fast frequency response and stability are achieved. The proposed model is validated under varying irradiance conditions, load switching, grid outages and line faults incorporating fault ride-through capability in GFM-based control. The proposed controller was simulated in a 100 MW solar PV system and 60 MW BESS using the MATLAB/Simulink 2023 tool, and the experimental setup was validated in a 1 kW grid-connected system. The percentage improvement of the system frequency and voltage with FRT-capable GFM control is 69.3% and 70%, respectively, and the percentage improvement is only 3% for system frequency and 52% for grid voltage in the case of an FRT-capable GFL controller. The simulation and experimental results prove that GFM-based inverter control achieves fast frequency response, and grid stability is also ensured.

Coordinated reactive power control for hybrid cascaded high‐voltage direct‐current links in weak AC grids

AbstractThe hybrid cascaded high‐voltage direct‐current (HC‐HVDC) links are recently introduced for ultra‐high voltage bulky power transmissions. However, as wind power becomes more prevalent, the grid is gradually weakened and will face voltage stability issues. This paper proposes a coordinated reactive power control strategy for HC‐HVDC links to enhance the voltage stability of AC bus. Firstly, the impact of HC‐HVDC on the static voltage stability of the AC bus is studied by the voltage sensitivity coefficient. Then, the limitation of reactive power capability of modular multilevel converter in the HC structure is identified. Based on the analysis results, a coordinated reactive power control strategy based on adaptive voltage droop is proposed. In the strategy, the DC voltage ratio is regulated according to the fluctuation degree of the AC bus voltage to adjust the reactive power of HC‐HVDC, which realized the dynamic voltage support for the AC bus. Finally, electromagnetic simulations in power systems computer aided design (PSCAD)/electromagnetic transients including DC (EMTDC) are performed, and the results validate the theoretical findings and the effectiveness of the control strategy.

Small Signal Modelling and Stability Analysis of a Grid Connected Inverted Based Microgrid

Objectives: This work focuses on the stability analysis of grid connected microgrids. It considers the impact of load disturbance and grid voltage change on voltage and current levels, as well as reactive and active power responses, is analysed. Methods: A comprehensive small-signal state-space model is developed for an inverter-based microgrid, incorporating submodules of inverters, phase-locked loops (PLLs), and LCL filters. The model is linearized around a stable operating point, and eigenvalue analysis is performed and validated through MATLAB/Simulink simulations. A current controller operating in the d-q frame is proposed to enhance stable power conversion and maintain microgrid stability. Findings: The proposed model and control strategy demonstrate the microgrid's ability to maintain transient voltage stability under severe dynamic conditions. During a 10% grid voltage fluctuation, the microgrid exhibits stable active and reactive power responses, with currents and voltages at the point of common coupling stabilizing within 0.2 seconds. Furthermore, when a 25 kVA active load is disconnected, the microgrid effectively manages the power transition, maintaining stable operation with minimal deviations in key parameters. The current controller simplifies AC current control, integrating active power management from solar input, DC-link voltage stability, and reactive power control. Novelty: The novelty lies in the comprehensive analysis of transient voltage stability in grid-connected microgrids under grid voltage fluctuations and load disturbances, areas that have received limited attention in previous research. By developing a detailed small-signal state-space model incorporating PLL and LCL filter dynamics and proposing a robust control strategy with the current controller, this study offers new insights into enhancing the resilience and reliability of grid-connected microgrids during transient events. Keywords: Microgrid, Small Signal Stability, Voltage Source Inverter, State Space model, Eigen Values

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Reinforcement learning-driven proximal policy optimization-based voltage control for PV and WT integrated power system

The depletion of conventional fuel reserves and the high carbon emissions have alarmed the energy sector drivers. The integration of renewable energy resources (RERs) towards power system transformation is an obvious approach for a new-zero future. However, this integration also brings challenges in terms of voltage stability and power losses due to the variable output of RERs. To address these challenges, this work proposes a novel approach utilizing photovoltaic (PV) inverters and static var compensators (SVCs) for reactive power control in power distribution networks (PDNs). It enhances voltage stability and minimizes power losses. The proposed study deploys a proximal policy optimization (PPO) algorithm for real-time communication and control between reactive power devices. Performance evaluation was made on an IEEE-33 Bus system to demonstrate the effectiveness of the proposed scheme in integrating RER-based distributed generators (DGs). The proposed system achieved 68 % voltage control, keeping the voltage within a certain range of ±5 % while minimizing power losses. The proposed system also reduced the voltage out-of-control ratio to 0.044, which indicates minimum voltage deviation from the standard value. The proposed study provides a promising solution for controlling the voltage of DGs integrated PDN, which can potentially enhance the efficiency and reliability of the power system.