Voltage Mitigation Research Articles

Power quality enhancement of grid-integrated solar photovoltaic system with unified power quality conditioner

Introduction. To enhance the quality of power and ensure a consistent electricity supply, this study proposes the utilization of a unified power quality conditioner (UPQC) system integrated with solar photovoltaic (PV) technology. The innovation involves single DC-link connecting back-to-back voltage-compensating components arranged in series and shunt, forming the PV-UPQC. The shunt compensator utilizes energy from a PV array to address harmonics in the load current. The objective is to mitigate voltage dips and spikes by injecting voltage that is either in phase with or out of phase with the common coupling point through a series compensator. The method combines the benefits of generating renewable energy to enhance electrical quality. The goal of the paper is the power quality enhancement of grid-integrated solar PV system. The novelty of the proposed work consists of enhancement of grid-integrated solar PV system with UPQC. The purpose of integrating a UPQC into a grid-connected solar PV system is to enhance power quality by mitigating issues such as voltage fluctuations, harmonics and reactive power imbalance. Methods. The proposed topology is implemented in MATLAB/Simulink with grid-integrated solar PV system with UPQC. Results. Integrating UPQC with a grid-connected solar PV system yields substantial improvements in power quality. This includes effectively mitigating voltage fluctuations and harmonics, resulting in smoother operation and reduced disturbances on the grid. Practical value. The proposed topology has proven to be extremely useful for grid-integrated solar PV system with UPQC applications. References 15, table 2, figures 9.

Common mode voltage mitigation in a three phase 21-level asymmetrical inverter fed induction motor

Common mode voltage mitigation in a three phase 21-level asymmetrical inverter fed induction motor

Enhancing off-grid wind energy systems with controlled inverter integration for improved power quality

Introduction. Off-grid wind energy systems play a pivotal role in providing clean and sustainable power to remote areas. However, the intermittent nature of wind and the absence of grid connectivity pose significant challenges to maintaining consistent power quality. The wind energy conversion system plays a central role in tapping renewable energy from wind sources. Operational parameters such as rotor and stator currents, output voltages of rectifiers and converters, and grid phase voltage variations are crucial for stable power generation and grid integration. Additionally, optimizing power conversion output through voltage gain analysis in boost converters is essential. Moreover, ensuring electricity quality via total harmonic distortion reduction in inverters is vital for grid compatibility. Goal. Enhancing the power quality of grid-integrated wind energy conversion systems. Methods. The proposed topology is implemented in MATLAB/Simulink with optimized control strategies for enhancing power quality in off-grid wind energy systems. Results. Control strategies with a grid-connected wind energy conversion system yields substantial improvements in power quality. This includes effectively mitigating voltage fluctuations and harmonics, resulting in smoother operation and reduced disturbances on the grid. Practical value. The proposed topology has proven to be extremely useful for off grid-integrated wind system. References 18, table 1, figures 11.

Active filter parameter tuning method for harmonic voltage mitigation in wind power plants

It is challenging to determine the active filter control factors in wind power plants (WPP) to obtain effective harmonic voltage mitigation and avoid over-modulation or system instability problems caused by overlarge feedforward or feedback gains. To address this issue, an active filter tuning (AFT) method is proposed in this paper to offer a common parameter tuning and stability assessment strategy for both current-controlled and voltage-controlled harmonic impedance reshaping (HIR) methods by introducing a coordination factor including different weight coefficients for system stability margin, wind turbine (WT) harmonic suppression, and grid harmonic mitigation. The superiority of the proposed method is verified in a 20 MW WPP with four cases considering both WT harmonic voltage amplification and grid voltage amplification. Compared to previous methods, the AFT-based HIR method achieves a more flexible balance between system stability and harmonic voltage mitigation, obtaining better performance in WT harmonic suppression, grid harmonic suppression, system robustness, and transient response.

Multi-agent deep reinforcement learning with enhanced collaboration for distribution network voltage control

Due to the increasing high penetration of Photovoltaic (PV), it brings great challenge for voltage control issue of distribution network. To address this problem, this paper presents an improved collaborative Multi-Agent Reinforcement Learning (MARL) approach for proactive voltage control, aimed at mitigating voltage violations and minimizing power losses. The self-attention mechanism is embedded into the multi-agent soft actor-critic (MASAC) algorithm to enhance the collaboration of multi-agent system, which can well improve the learning efficiency to ensure the voltage safety of Distribution Network. In addition, the proposed learning approach is implemented on IEEE 33-bus, 141-bus and 322-bus systems, and the simulation results reveal that the proposed approach can control the voltage into safety domain as well as reduce power losses.

Research on power quality improvement system based on dynamic voltage restorer

AbstractPower quality is a critical issue in power systems that can affect the performance and reliability of sensitive equipment. The dynamic voltage restorer (DVR) is a widely used technology for improving power quality, but it mainly focuses on mitigating voltage sags and often neglects the issue of harmonic distortion. This paper proposes a DVR voltage compensation strategy based on the discrete Fourier transform (DFT). This strategy utilizes the DFT to analyze the voltage waveform, separating the fundamental and desired harmonic components. With this strategy, the DVR can effectively compensate for voltage sag and achieve selective harmonic compensation, thereby improving the power quality of the power system. Additionally, a method utilizing hardware circuitry and an LED as a timestamp is proposed to dynamically estimate digital siginal processor (DSP) resource occupancy rate in real‐time, ensuring effective compensation while minimizing resource occupancy. A 3 kW DVR experimental prototype was constructed and tested to evaluate the practicality of the proposed strategy. The simulation and experimental results show that the method proposed in this paper successfully realizes the compensation of voltage sag and harmonics in the power system, and improves the stability and reliability of the power system.

Mitigation of common mode voltage in ultra sparse matrix converters using auxiliary shoot‐through switches for wind energy systems

SummaryThis paper targets to minimize the peak common mode voltage (CMV) in ultra sparse matrix converters (USMC) by applying new zero vectors for the space vector modulation technique (SVM). Conventional zero vectors in the SVM raise the peak CMV by 42.23%. An increased magnitude of CMV is associated with the occurrence of leakage current, hence resulting in insulation degradation. So, the reduction of peak CMV is necessary for USMC. The proposed method offers suitable switching arrangements using auxiliary shoot through (AST) switches to minimize the peak‐to‐peak CMV. This proposed method holds the advantages of the conventional method, like a wide range of modulation index and zero current switching at the rectifier side, and also reduces the CMV problem. This paper also provides a comparative analysis of the existing reported methods and the proposed method. The effectiveness of the proposed method is validated through both simulation and experimental results.

A Comprehensive Review on Space Vector Based-PWM Techniques for Common Mode Voltage Mitigation in Photovoltaic Multi-Level Inverters

Nowadays, transformer-less photovoltaic (PV) multi-level inverters (MLIs) are commonly employed in both industrial and residential settings. This structure has attracted increased attention due to its unique advantages, such as higher efficiency, lower cost and size, better waveform quality, and inherent fault tolerance. However, due to the removal of the transformer, the common mode voltage (CMV) becomes one of the crucial issues in transformer-less PV MLIs. The high-frequency variation in CMV results in a leakage current that deteriorates the line current quality, increases the PV power system losses, leads to severe electromagnetic emissions (EMI), reduces the PV array lifespan, and causes personal safety problems. In this regard, this paper presents a review of the existing and recent research on modulation techniques based on space vector pulse width modulation (SVPWMs) that overcome this issue in transformer-less three-level NPC-MLIs (3L-NPC-MLIs). The reduced CMV-SVPWM (RCMV-SVPWM) can be mainly categorized as an RCMV-SVPWM based on the vector type, based on virtual vectors, and based on the two-level SVPWM (2L-SVPWM). Their features and their limitations in terms of several main criteria are discussed. In the final section of this paper, some challenges and future trends for this research area are projected.

Self-Measurement of the Admittance Matrix of AC–DC Power Converter by Internal Harmonic Injection

Frequency-domain impedance or admittance model is widely applied to analyze harmonic stability of power electronic converters. Conventionally, the converter impedance is modeled holistically, without exhibiting the sole effect of different control and phase-locked loop (PLL). Besides, harmonic voltage or current injection external to the converter is usually adopted, which involves dedicated equipment and introduces unexpected inner impedance. In this paper, the response of voltage perturbation upon AC-DC power converter along various voltage signal flow paths is analyzed, based on superposition principle. Each part of admittance and its effect on stability can therefore be quantified explicitly. By injecting harmonic perturbation through the identified paths within the converter controller, each part of admittances, with and without the concerned control or PLL blocks, are measured and summed to be the total admittance. Harmonic voltage mitigation control implemented on a grid-forming converter creates an ideal grid with constant voltage and nearly zero inner impedance at the injected harmonic frequency. The proposed admittance analysis and measurement is successfully applied to power converter with different PLL, voltage feedforward, output power control, DC voltage control and grid-forming cascaded control. Effectiveness of the analysis and the proposed admittance measurement approach are validated by comprehensive simulation and hardware test.

Unified power quality conditioner (UPQC) with voltage dips and over-voltages compensation capability

Unified power quality conditioners (UPQCs) allow the mitigation of voltage and current disturbances that could affect sensitive electrical loads while compensating the load reactive power. Diverse control techniques have been proposed to evaluate the instantaneous output voltage of the series active power filter of the UPQC but, in most cases, these controllers only can compensate a kind of voltage disturbance. This paper proposes a new digital controller for UPQCs which allows the load current harmonics and reactive power to be compensated at the grid side while avoiding the effect of voltage dips, over-voltages and voltage harmonics on the local loads. The controller characteristics can be established on-line without changing its basic structure. The performance of the proposed controller has been evaluated through simulation tests.

Optimum PI controllers of active power filters for harmonic voltage mitigation in multibus industrial power systems.

The bus voltage and branch current detection control strategies of the active power filters used in multibus power systems for harmonic voltage mitigation are analysed in terms of the optimum gains of PI controllers

Coordinated Q‐V/P‐f Control Strategy Using Virtual Power Factor for Autonomous AC Microgrid with PV Smart Inverters

Given the increasing interests in carbon neutrality due to climate change, photovoltaic (PV)‐based microgrid has become an important research topic worldwide. Typically, high PV penetration without proper control schemes causes power quality issues such as voltage or frequency violation, resulting in the limited PV hosting capacity. Reactive and active power support from the PV is effective to solve the issues, however, it is a critical challenge to efficiently contribute to the stabilizing controls under the inverter capacity constraint. Recent studies have applied smart inverters, equipped with fixed active and reactive power control reserves, for dynamic voltage and frequency support. In this paper, we proposed a control strategy in which the control reserves for voltage and frequency support are flexibly adjusted using virtual power factor (VPF) to improve the power quality with reducing active power curtailment. The effectiveness of the proposed Q‐V/P‐f control is verified through numerical simulations using a microgrid model developed in MATLAB/Simulink platform. It was observed through the simulation that the proposed method contributed to mitigating voltage and frequency fluctuation with satisfying the inverter capacity constraint. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Mitigation of Voltage and Frequency Oscillations of a Microgrid during Wind Gust by Using Fuzzy-Controlled Flywheel Energy Storage

Mitigation of Voltage and Frequency Oscillations of a Microgrid during Wind Gust by Using Fuzzy-Controlled Flywheel Energy Storage

Improving Active Resonance Damping and Unbalanced Voltage Mitigation Based on Combined DDSRF and Washout Filter in Islanded Microgrids

Improving Active Resonance Damping and Unbalanced Voltage Mitigation Based on Combined DDSRF and Washout Filter in Islanded Microgrids

Mitigation of Voltage by Using PV-Connected Super-Lift Luo Converter under Variation of Temperature

Abstract: This paper focuses on application a special type of DC-DC Converter called Super-Lift Luo Converter for load voltage mitigation due to variation in temperature. The converter is fed by a PV(Photovoltaic) System as input and its output is converted to AC Voltage by a Cascaded H-Bridge Inverter and this is integrated with grid and connected to load. In this work, the SuperLift Luo Converter performance is studied.

Review of Challenges and Opportunities in the Integration of Electric Vehicles to the Grid

Electric vehicle (EV) technology has revolutionized the transportation sector in the last few decades. The adoption of EVs, along with the advancement of smart grid technologies and Renewable Energy Sources (RES), has introduced new concepts in the automobile and power industries. Vehicle-Grid Integration (VGI) or Vehicle-to-Grid (V2G) is a technology revolutionizing both the transport and electric power sectors. From a V2G perspective, these sectors are complementary and mutually beneficial. For the power sector, mitigation of voltage and frequency excursions and the prospect of grid stabilization on the brink of uncertainties owing to the dynamics in the grid scenario are very important. This article focuses on various aspects of EV-power grid integration. The tremendous benefits of this technology, as presented in the literature, are reviewed. Furthermore, the concerns and the implementation challenges are reviewed in detail in this work.

Variable Reactance Criteria to Mitigate Voltage Deviations in Power Transformers in Light- and Over-Load Conditions

In this paper, variable reactance (VR) criteria are proposed to mitigate voltage deviations in power transformers under light-load inductive and capacitive conditions, as well as for over-load conditions. Under capacitive load conditions, power transformers are affected by the Ferranti effect as much as AC lines are and can suffer damage if a large over-voltage is present at the secondary winding. A classical solution for this is the installation of expensive and bulky inductive reactors at different locations of the AC lines to absorb the reactive power. Instead, this paper addresses VR techniques focused on power transformer reactance modification to compensate for the over-voltage. With these techniques, the Ferranti effect on power lines can also be reduced. Another benefit is the cancellation of over-voltages whose cause is different from the Ferranti effect, namely under inductive load conditions. In addition, they can also enhance the parallel operation of power transformers by allowing more flexibility for overload sharing among transformers. The VR techniques are derived from the Kapp phasor-diagram theory and have been validated experimentally at a small scale in the laboratory. When implemented in a big network, they can also improve the load-flow voltage and AC line-loading profiles and even increase the power factor of certain generators.

Comparative Performance Study of DVR Using Adaptive LMS Filtering-Based Algorithms

In the distribution system, voltage sags and swell have adverse effects on sensitive and critical loads. Dynamic Voltage Restorer (DVR) play a vital role to mitigate voltage sags and swell through its organized control when connected in series with the system. Various conventional control schemes have been reported for the control of DVR. The performance of DVR with these schemes has been successful in the mitigation of voltage sags/swell, but drawbacks, such as undershoot, and overshoot during sag dynamics are observed in the regulated load terminal voltage. These drawbacks may cause malfunctioning of the equipment connected and hence their elimination is indispensable. With this inspiration, a novel Adaline filter-based adaptive control scheme using learning-rate parameter-based Least-Mean-Square algorithm has been proposed. This scheme has the capability to overcome the drawbacks with the conventional control schemes thus improving the performance of DVR. In this paper, the performance of DVR using proposed algorithm is compared with that using synchronous reference frame (SRF)-based conventional control scheme. The performance is studied and validated through simulation results under different voltage sag and swell conditions in MATLAB software using Sim Power System toolboxes.

Mitigation of Common Mode Voltage in Induction Motor Employing Multilevel Inverter

Induction motor (IM) is a usually a constant speed motor. The Basic technique used to control and run the machine in variable speed drive application can be obtained by two level inverters, which can be controlled digitally with the help of microcontroller using sinusoidal pulse width modulation method. Thereby at the star terminal point of the load there is a voltage existed with respect to system ground. Hence it is defined as “common mode voltage”. Due to the common mode voltage, there is an electromagnetic interference that is induced. Thereby it causes lot of disturbance to the communication and electronic equipment’s, which are nearby to the system. The common mode voltage can be reduced with the help of high-level inverter that can be used for example two-level, three-level, four-level inverters etc. In this proposed system we are reducing the common mode voltage by using two level inverter & three level inverter. In this paper, mitigation of CMV is simulated through MATLAB and implemented by hardware setup.

Paralleled Inverters to Drive Double Dual-Three-Phase Induction Motors With Common-Mode Voltage Mitigation for Traction Application

Paralleled Inverters to Drive Double Dual-Three-Phase Induction Motors With Common-Mode Voltage Mitigation for Traction Application