Dynamic Voltage Regulation Research Articles

Honey Badger Algorithm Based DVR Controllers for Improved Power Quality‏ in a Microgrid Combined of (Wind System\ Grid\Nonlinear Load)

Power quality (PQ) is crucial in today's energy supply networks, where even little voltage fluctuations can have a big impact on how well household appliances and technologies operate. The suggested dynamic voltage regulator (DVR) approach helps to create a new generation power grid that is more dependable and effective. In this study, the honey badger optimizer (HBO) is used to optimize the controllers of the DVR for improving PQ via voltage control. The efficacy of the optimized DVR is further increased by its integration with a microgrid (MG) wind supply. The suggested technique makes use of a low-complexity control approach for voltage regulation to adjust for harmonic distortion, swells, and voltage dips in the addressed system. The technique accomplishes voltage improvement, bus stabilization, energy-efficient utilization, and harmonic distortion reduction by using the DVR in conjunction with an MG wind supply. Various voltage disturbances, such as balanced and unbalanced swell and sag, voltage imbalance, notching, various fault states, and power system harmonic distortion, are taken into consideration to show the approach's usefulness. The findings indicate PQ enhancement, demonstrating that the load voltage roughly matches the nominal value.

Dynamic Voltage Regulation in Active Distribution Networks Using Day-Ahead Multi-Agent Deep Reinforcement Learning

Dynamic Voltage Regulation in Active Distribution Networks Using Day-Ahead Multi-Agent Deep Reinforcement Learning

A Computational and Experimental Performance Analysis of an Electromagnetic Voltage Regulator Proposal throughout Controlled Series Voltage Injection

Power quality problems related to short or long time voltage variation have motived the search for voltage compensator techniques capable to provide dynamic voltage regulation to accomplish voltage supply levels in accordance with electrical energy agencies acceptable levels. Although one could recognize that a variety of products already offered in the market are capable of attending general electrical power system requirements the available technology comprises quite simple devices till very sophisticate ones. Having in mind the combination of simplicity, competitive cost, low maintenance need and an attractive performance at recovering the voltage deviations, then an electromagnetic concept to restore the desirable voltage within the established voltage levels is here proposed. The control strategy to be used can provide properties that enable this new device at proving the time response in accordance with the needs for long term and short term voltage variations. Concerning the proposed compensator physical topology it consists in extracting the necessary electrical power throughout a shunt transformer and the injection via a series unit. Besides the arrangement, the paper goes further by establishing a computational time domain model and a laboratory experiment to highlight the overall structure effectiveness at compensating voltage changes.

Voltage Drop Compensation Technology for High-Voltage and High-Power DC Energy Storage Power Supply System

This paper presents an output voltage drop compensation technology for high-voltage and high-power DC energy storage system (DC-ESS). This technology is used to improve the output voltage stability of high-voltage high-power DC-ESS in high rate discharge. The proposed output voltage drop compensation technology includes an ESS architecture and a corresponding control method. The proposed ESS architecture adopts DC dynamic voltage regulator (DC-DVR) to compensate for output voltage drop. DC-DVR adopts 6-phase interleaved parallel buck converter. This architecture not only maintains the system output voltage stability, but also reduces the system cost. Moreover, the proposed ESS architecture does not change the original energy storage capacity. The dynamic power flow of the proposed ESS architecture is analyzed and a direct power control method based on full response power compensation is proposed. The steady-state power and dynamic power of the proposed ESS architecture are compensated respectively, so that the input power can quickly track the change of the output power. The proposed control method improves the stability and dynamic response speed in the system dynamic process. Simulation and experiment verify the effectiveness of the proposed ESS architecture and control method.

Modeling, Integration and Simulation of the Photovoltaic Power Plant Considering LVRT Capability and Transient Voltage Stability

This paper investigates how high photovoltaic energy penetration impacts dynamic performance and voltage regulation of the modified IEEE-9 bus grid. The transmission power system was modeled and simulated using PSCAD-EMTDC software to conduct the study. Load flow analysis is implemented to explore the power system’s capability to incorporate the desired photovoltaic power. Moreover, the study is based on time response simulations to grid disturbances. The supply and control of reactive power from solar power generation plants are becoming critical issues to study because they can facilitate the integration of PV in power grids under different operating conditions. Network-related faults like a PV solar power plant event outage, a three-phase short-circuit at a conventional bus, and a voltage dip at the PV solar power plant have been considered. The results will help identify the protective devices and strategies needed to maintain the stability and reliability of the system operation and transient analysis of the network under external power network fault and recovery operation. Thus, it has practical significance for real utility studies. Moreover, this comprehensive study will be a valuable guide for assessing and improving the grid’s performance under the study of any other grids, which also gives the vast potential and need for solar energy penetration into the grid systems.

Renewable energy based low-voltage distribution network for dynamic voltage regulation

With the continuous integration of renewable energy and the complexity of power system, dynamic voltage regulation of low-voltage distribution network has become an urgent problem to be solved. Through in-depth analysis and theoretical discussion, the mathematical model of low-voltage distribution network is established, and the control strategy based on renewable energy is designed for dynamic voltage regulation. Through simulation experiment and field verification, the superiority of the proposed method compared with the existing method is demonstrated. In addition, the sensitivity of the parameters and the stability of the control strategy are also comprehensively analyzed. Despite some limitations and challenges, the results of this study provide strong support for the sustainable, efficient and safe operation of low-voltage distribution networks, and further optimization and expansion in many aspects are needed in the future.

A robust microgrid using an inverter with CCS-MPC control and resilient operation

Modern generation trend through renewable energy-based distributed energy resources has made microgrids an important part of the power system. Robust control of the inverter providing quality power has become an essential microgrid (MG) requirement. This paper proposes continuous control set model predictive control (CCS-MPC) on inverter for dynamic voltage regulation supplying reactive power to the load for a MG. The proposed method uses the terminal voltage magnitude, which reduces calculation time, sensor per phase, and the engagement burden of the controller. This paper applies a nonlinear VSI model and a series parallel structure nonlinear autoregressive exogenous (NARX) model of artificial neural network (ANN) to predict future output which CCS-MPC optimizes. The proposed VSI with CCS MPC is applied to a case study of a real system as a plug-and-play device. Simulation shows the satisfactory result of the proposed controller. The inverter control system has been made resilient to protect itself and automatically recover from faults on the DC and AC side, providing quality power to its local load when the fault has been removed.

Improvement of Voltage Profile in Photo Voltaic System using Dynamic Voltage Regulator

This examination centers around further developing the voltage profile in a crossover power framework with a PV association using a unique voltage restorer. The objective of this work is to raise the framework's power quality. Regardless of whether voltage hang and swell happen on both the transmission and appropriation sides, the issue is just fixed there. A calculated procedure is utilized, expecting the components expected to foster the framework. A powerful voltage restorer that is associated in series perceives voltage glimmering immediately and reestablishes high voltage to its unique levels. This model's plan effectively settle the voltage glimmering issue also. MATLAB Simulink is utilized to reenact the outcomes, which explained the framework's importance.

Optimal Distributed Coordinated Reinforcement Learning for Secondary Voltage Control in Time-Delayed Microgrid

This article proposes an optimal distributed secondary voltage control method based on distributed coordinated reinforcement learning (DCRL) algorithm in the time-delayed microgrid. First, a distributed secondary voltage control protocol through a sparse communication network is designed using consensus-based algorithm and Lyapunov–Krasovskii theory. Then, by combining the consensus control method with reinforcement learning together, a novel DCRL algorithm is utilized to dynamically adjust the voltage controller gains. Since the DCRL method is an online intelligent algorithm, it can adaptively improve the voltage control performance in the presence of various external disturbances encountered in microgrid secondary control. The effectiveness of the proposed method is verified through simulations under different scenarios on a four inverter-based microgrid test system. Simulation results indicate that our method shows superior dynamic voltage regulation response over traditional methods.

Enhancing transient stability and dynamic response of wind-penetrated power systems through PSS and STATCOM cooperation

The large-scale integration of doubly-fed induction generator (DFIG) based wind power plants poses stability challenges for power system operation. This study investigates the transient stability and dynamic performance of a modified 3-machine, 9-bus Western System Coordinating Council (WSCC) system. The investigation was conducted by connecting the DFIG wind farm to the sixth bus via a low-impedance transmission line and installing power system stabilizers (PSSs) on all automatic voltage regulators (AVRs). A three-phase fault simulation was carried out to test the system, with and without power system stabilizers and a static synchronous compensator (STATCOM) device. Time-domain simulations demonstrate improved transient response with PSS-STATCOM control. A 50% reduction in settling time and 70% decrease in power angle undershoots at the slack bus are achieved following disturbances, even at minimum wind penetration levels. Load flow analysis shows the coordinated controllers maintain voltages within 0.5% of nominal at 60% wind penetration, while voltages at load buses can deviate up to 15% without control. Eigenvalue analysis indicates the PSS-STATCOM boosts damping ratios of critical oscillatory modes from nearly 0% to over 30% under high wind injection. Together, the present findings provide significant evidence that PSS and STATCOM cooperation enhances dynamic voltage regulation, angle stability, and damping across operating ranges, thereby maintaining secure operation in systems with high renewable integration.

The power harmonic components distribution study in the power circuit of a dynamic voltage restorer

Purpose. Investigation of the distribution of harmonic power components in the power circuit of a dynamic voltage restorer. Methodology. On the basis of the differential equations of the power circuit of a dynamic restorer, a search for the relationship between the mode parameters and the parameters of the circuit elements is performed. On the basis of the obtained expressions, a model of a dynamic voltage regulator was created using the methods of mathematical modeling in the visual programming environment.. Findings. The equations that reflect the relationship between the mode parameters of a dynamic voltage restorer and the parameters of circuit elements are obtained. As a result of modeling the mode with different harmonic composition of current and voltage, the following features of the distribution of instantaneous power components are revealed. Originality. It has been established that the presence of different current and voltage harmonics acting in the transformer of a dynamic restorer causes additional power harmonics that are transformed in the windings. It is noted that the low-frequency power harmonics of the LC filter dominate on the capacitor, which is connected in parallel to the transformer winding, while the level of high-frequency components caused by PWM modulation for the capacitor and the filter choke differ slightly. The zero-frequency power component of the storage capacitor corresponds to a tripled zero-time power component at the output of the converter, which is due to its operation in three phases. This cannot be extended to the second and third harmonics of the powers of the converter and the capacitor; these components are absent in the latter, which is due to energy exchange processes between the phases of the converter. Practical value. Using the obtained expressions, the principle of determining the parameters of the elements of the power circuit of a dynamic voltage restorer, in particular, the storage elements, is formulated.

MPC Based Dynamic Voltage Regulation Using Grid-Side BESPS With the Consideration of Communication Delay

Battery energy storage power stations (BESPS) play an important role in the power flow regulation in large-scaled micro-grids. It is proposed that the static Var compensator (SVC) be replaced by BESPS through activation of its dynamic voltage regulation (DVR) function so that the cost of SVC can be saved. An additional controller named energy storage coordination controller (ESCC) is needed to support the control algorithm of DVR and coordinate the individual battery energy storage system units. However, communication delay between the ESCC and the commercial BESS units is compounded by the difficulty of measuring the micro-grid (MG) bus voltage by ESCC. These issues should be considered in the design of the BESPS controller to avoid compromising the micro-grid operation. In this paper, we will be investigating model predictive control (MPC), Smith Predictor and PI based control schemes to deal with the communication delay issue. Kalman Filter based observer is designed to monitor the MG bus voltage as a feedback signal of the ESCC. The stability of the proposed method is further discussed and the results using the control hardware-in-the-loop (CHIL) testing are presented.

Power Quality Analysis of Fuzzy DVR based Hybrid Solar PV-PEMFC System Under Severe Disturbance

Hybrid Energy System (HES) is becoming popular as it is identified as the most safe, sustainable, and long-term option for energy management. The grid-connected power network is vulnerable to frequent interruptions, which can lead to instability and a huge blackout. Furthermore, the presence of switching devices in industrial and domestic applications causes disturbances such as voltage swell/sag, waveform distortion, interruptions, impulsive voltage, and so on. Dynamic voltage restorer, known as a modern power compensating device, is cost effective, compact in size and can handle more energy capacity than DTSATCOM and UPFC. Hence for addressing the power quality issues in hybrid solar photovoltaic (PV)-proton exchange membrane fuel cells (PEMFC) system, dynamic voltage restorer (DVR) has been designed in this paper. As the fuzzy logic technique can provide flexible solutions in the case of uncertainty, fuzzy logic-based controller has also been employed with DVR to regulate the firing pulses of a PWM generator. Based on the simulation results obtained using fast fourier transform (FFT) analysis in MATLAB/Simulink, the dynamic performance of HES against the most important contingency condition or three phase faults is analyzed in detail. Further, the impact of DVR on power quality improvement under severe fault has also been demonstrated in this research work. On analyzing the total harmonic distortion (THD) values of HES under heavy disturbances, the fuzzy controlled dynamic voltage regulator (FCDVR) is identified as an efficient control mechanism for enhancing power quality in grid-connected HES.

The use of numerical method in an electric grid coupled to a wind farm to compare different kinds of flexible AC transmission systems

The PSAT software was used in this study to analyse and compare the performance of hybrid compensators such as SSSC-STATCOM (controllers), TCSC-SVC (compensators), and UPFC in an electric grid coupled to a wind farm. The flexible AC transmission system (FACTS) technology is used to provide a continual power flow and to provide new ways to control the electric system network. In the FACTS devices, the UPFC (Unified Power Flow Controller) is one of the most adaptable, flexible, and complicated power electric devices. The active and reactive power flows and the local voltage on the bus can be regulated by UPFC; it can also resolve the problem of harmonics. The TCSC (Thyristor-Controlled Series Capacitor) consists as a series-compensating capacitor shunted by a thyristor-controlled reactor. The SVC (Static Var Compensator) is the first shunt generation FACTS controller. We can observe that the UPFC controller has an effective power flow control, shorter setting time and a shorter overshoot. The UPFC obtained a well-known reputation for high controllability in power systems. The multilevel Unified Power Flow Controller can be operated in Static Synchronous Compensator (STATCOM), in Static Synchronous Series Compensator SSSC and exactly in the UPFC compensator. The results of this research compare the hybrid controllers and investigate the effects of TCSC-SVC, SSSC-STATCOM, and UPFC on voltage, phase angle stability, and the active and reactive power in the tested system. The purpose of this comparison is to improve dynamic voltage regulation, especially when the utilisation of nonlinear loads and the presence of fault and breaker rise. These hybrid controllers have been shown to outperform series or shunt compensators; however, when compared to hybrid compensators SSSC-STATCOM, TCSC-SVC, and UPFC, the results employing the numerical method in the UPFC are more significant. The UPFC is the best hybrid controller in this study, and the compensators SSSC-STATCOM outperform the controllers TCSC-SVC.

Intelligent Voltage Control Method in Active Distribution Networks Based on Averaged Weighted Double Deep Q-network Algorithm

High penetration of distributed renewable energy sources and electric vehicles (EVs) makes future active distribution network (ADN) highly variable. These characteristics put great challenges to traditional voltage control methods. Voltage control based on the deep Q-network (DQN) algorithm offers a potential solution to this problem because it possesses human-level control performance. However, the traditional DQN methods may produce overestimation of action reward values, resulting in degradation of obtained solutions. In this paper, an intelligent voltage control method based on averaged weighted double deep Q-network (AWDDQN) algorithm is proposed to overcome the shortcomings of overestimation of action reward values in DQN algorithm and underestimation of action reward values in double deep Q-network (DDQN) algorithm. Using the proposed method, the voltage control objective is incorporated into the designed action reward values and normalized to form a Markov decision process (MDP) model which is solved by the AWDDQN algorithm. The designed AWDDQN-based intelligent voltage control agent is trained offline and used as online intelligent dynamic voltage regulator for the ADN. The proposed voltage control method is validated using the IEEE 33-bus and 123-bus systems containing renewable energy sources and EVs, and compared with the DQN and DDQN algorithms based methods, and traditional mixed-integer nonlinear program based methods. The simulation results show that the proposed method has better convergence and less voltage volatility than the other ones.

Phasor measurement units‐based fast voltage control strategy for distribution network with high‐penetration distributed photovoltaic

AbstractAs the penetration of distributed photovoltaic (PV) in the distribution network continues to increase, the problem of voltage violation is becoming increasingly prominent. PV output has strong volatility and uncertainty, leading to higher requirements on speed and accuracy of voltage control. The voltage qualification rate of the distribution network with PV is difficult to guarantee if relying on traditional measuring installation and discrete regulators. Thus, it is necessary to introduce high‐frequency sampling devices and various continuous regulators in real‐time voltage control. In this paper, a fast voltage control strategy by real‐time coordination of dynamic voltage regulators (DVRs) and PV inverters based on phasor measurement units (PMU) and remote terminal unit (RTU) information is proposed. The voltage sensitivity is calculated online based on the fast measurement information of PMU. The equivalent models of rapid voltage regulators including DVR and PV inverter are established for the online extraction of voltage optimal control gradients. According to the model predictive control (MPC) theory, a feeder‐level global voltage control strategy is proposed comprehensively considering the objectives of voltage qualification rate, control cost, and network loss, which can realize real‐time voltage control in the distribution network at the millisecond scale. The effectiveness and rapidity of the proposed global voltage control strategy are verified in the IEEE 33‐bus system and a real representative distribution system for preventing voltage violation.

Design and Implementation of an 18-kW 500-kHz 98.8% Efficiency High-Density Battery Charger With Partial Power Processing

The demand for high-density, high-efficiency bidirectional battery chargers is driven by the fast development of energy storage system in renewable energy system, microgrid, and transportation electrification. Isolated dc–dc converter that interfaces a battery with a variable voltage range is one of the critical components. Input-parallel output-series (IPOS) partial power (PP) converter is considered a promising high-efficiency, high-density solution because only a fraction of power is processed via multistage converters to regulate the output voltage. However, due to the tight coupling between two dc transformers (DCXs), the design of PP converter is complicated. To solve this issue, an overall design procedure for a bidirectional soft-switching resonant-type PP converter is proposed. In the parameters design part, a decoupled design method is proposed to simplify the DCXs design. With this method, two DCXs can be designed separately, and a typical optimization method can be easily applied. As for the hardware design part, to minimize the ac loop inductance and resistance, a two-direction (2-D) flux cancellation method and an “intraleaving” winding structure are proposed for circuit layout and high-frequency (HF) transformer to obtain high operation efficiency and power density. Finally, the whole design procedure is verified by an 18-kW-rated, 25-kW peak, prototype operating at 500 kHz. The realized PP converter features a peak efficiency of 98. 8% and a power density of 142 W/in3. This article is accompanied by two videos demonstrating the dynamic voltage regulation test and the efficiency measurement.

Dynamic Voltage Regulation and Unbalance Compensation in a Low-Voltage Distribution Network Using Energy Storage System

Modern distribution grids may suffer problems of voltage distortion, especially along radial low-voltage feeders with a high penetration of intermittent, unbalanced and distorted loads and generation sources. It is a challenge to develop an effective voltage-regulation method using a straightforward implementation. This paper proposes a novel method for local voltage control and balancing using a shunt-connected energy storage system. The compensation principles are explained, and a complete controller design is proposed. The algorithm is designed to be implemented in power electronic converters that provide the interface between the storage and the grid. The original contribution is the development of a low-level control method, which includes voltage balancing and a method to minimize the compensator current and is to be implemented in power electronic converters that provide the interface between the storage and the grid. The calculation of active and reactive compensator currents is explained with relation to the estimated grid impedance. The efficacy of the designed controller is verified by laboratory experiments. It is shown that voltage regulation using the proposed method is achieved with less apparent power compared to a system where only reactive power is used. The controller presents a very good dynamic response to rapid voltage variations, such as unbalanced voltage dips. The applicability and constraints of the method are discussed with respect to the present state of the art in low-voltage-grid voltage regulation.

Optimizing PV-Hosting Capacity with the Integrated Employment of Dynamic Line Rating and Voltage Regulation

A record amount of renewable energy has been added to global electricity generation in recent years. Among the renewable energy sources, solar photovoltaic (PV) is the most popular energy source integrated into low voltage distribution networks. However, the voltage limits and current-carrying capacity of the conductors become a barrier to maximizing the PV-hosting capacity in low voltage distribution networks. This paper presents an optimization approach to maximize the PV-hosting capacity in order to fully utilize the existing low voltage distribution network assets. To achieve the maximum PV-hosting capacity of the network, a novel method based on the dynamic line rating of the low voltage distribution network, the coordinated operation of voltage control methods and the PV re-phasing technique was introduced and validated using a case study. The results show that the proposed methodology can enhance the PV-hosting capacity by 53.5% when compared to existing practices.

Voltage Regulation in a Radial Microgrid with High RES Penetration

Increasing installation of Renewable Energy Sources (RESs) in microgrids and distribution system feeders benefits the power system in many ways, such as increasing power availability and reliability, but they also cause various power quality issues, such as overvoltage and undervoltage, due to their intermittent nature. The sensitive loads, such as Constant Power Load (CPL), are affected by these voltage fluctuations. The approach proposed in this paper is to install a Dynamic Voltage Regulators (DVR) adjacent to the RES to suppress the voltage issue caused by it while leaving the sensitive load operation unharmed. The proposed concept is duly endorsed with analysis and simulations in MATLAB/Simulink environment.