Voltage Sag Research Articles

Two-stage Transient-stability-constrained Optimal Power Flow for Preventive Control of Rotor Angle Stability and Voltage Sags

Two-stage Transient-stability-constrained Optimal Power Flow for Preventive Control of Rotor Angle Stability and Voltage Sags

A comparative study of fuzzy logic based UPQC and D-STATCOM for mitigation of power quality problem

This paper begins by investigating a power quality problem in the case study area using monthly energy consumption data, the peak and minimum load of the substation, a fault summary, and the RMS voltage profile of the case study area. The content of the paper comprises three parts: the first involves MATLAB design and simulation of D-STATCOM with a fuzzy logic controller for the selected case study area. The second part entails MATLAB design and simulation of the DVR with a fuzzy logic controller. The final part presents a hybrid of the DVR and the D-STATCOM back-to-back using a DC link capacitor to implement a more recent and effective power quality improvement technique, namely UPQC. In the case of a three-phase fault, the voltage sag in the case study area is 0.6PU, with the remaining 0.4PU drop-down voltage requiring injection using the proposed FACT device for compensation. All proposed power quality problem mitigation techniques inject the required voltage and compensate for the voltage sag in the substation. For instance, D-STATCOM compensates the RMS voltage from 9KV to 14KV, DVR compensates the RMS voltage from 9KV to 14.7 KV, and UPQC compensates the value to 14.9KV. Due to the three-phase fault, the rise in reactive power of the existing outgoing feeder is 13MW. This unexpected rise in reactive power is reduced to 2.6 MW using D-STATCOM, DVR reduces it to 1.2 MW, and UPQC reduces the value below 1MW. The existing power factor of the case study area without any mitigation technique is 0.68. All proposed techniques improve the existing power factor to a more acceptable value. For instance, D-STATCOM improves the power factor from 0.68 to 0.83, DVR improves the value to 0.88, and UPQC, the more accurate power quality mitigation technique, improves the power factor to 0.93. Finally, the results are compared based on the simulation results.

Improving the Control Strategy of the DVR Compensator Based on an Adaptive Notch Filter with an Optimized PD Controller Using the IGWO Algorithm

One of the objectives of electrical distribution networks is to provide customers with access to high‐quality electricity. Because any disruptions in these systems result in voltage disorders, different devices are employed to offset these disruptions on consumers who are more susceptible. One of the most important and contemporary pieces of equipment that is connected in series with the network is dynamic voltage restoration (DVR), which shields delicate loads from network voltage issues by injecting the proper voltage. This article presents a DVR control scheme optimized with improved grey wolf optimization (IGWO) that uses a proportional derivative (PD) controller and adaptive notch filter (ANF). The output LC filter’s resistance has been removed, and the control system has actively engaged in oscillation damping in order to accelerate dynamic responsiveness and lower system losses. The major component of the voltage, which comprises its frequency, amplitude, and phase, is extracted using ANF. The capacitor current of the output filter in this structure is fed back to the control system and from the current mode control in the inner loop to boost stability. Owing to the occasionally complex dynamic behavior in distribution networks, particularly during a fault, the system’s frequency response has been altered and response speed has been accelerated using the PD controller. This kind of controller is distinguished by its accurate functioning in the presence of frequency deviations and its swifter dynamic reaction in the face of voltage swell and sag. In order to improve the THD and voltage sag indicators of the sensitive load, the PD coefficients were adjusted using the IGWO algorithm. As a consequence, the simulation results demonstrated that the suggested controller performed better than traditional controllers.

ПРОГРАММНЫЙ КОМПЛЕКС ДЛЯ РЕАЛИЗАЦИИ АСИНХРОННОГО ЧАСТОТНОГО ПУСКА ВЫСОКОВОЛЬТНЫХ ДВИГАТЕЛЕЙ И СНИЖЕНИЯ ВРЕМЕНИ ПЕРЕРЫВА В РАБОТЕ ДВИГАТЕЛЯ ПРИ КРАТКОВРЕМЕННОЙ ПОТЕРЕ ПИТАНИЯ

Relevance Most of the electricity consumed comes from electric drives (ED) of various technological processes. The most common way to increase the efficiency of an electric drive is the use of a variable frequency drive (VFD). However, the use of VFDs in some cases causes a decrease in the operating efficiency of the electric drive, this is due to the high sensitivity of the frequency converter to network voltage dips, leading to the failure of the inverter and to the stop of the technological process. A current direction is the development of algorithmic methods for increasing the stability of electric drives. Aim of research Increasing the stability of a frequency-controlled motor during emergency conditions in the power supply system. Development of a power supply circuit for an electric drive, and research into the algorithm for operating the inverter in emergency modes. Methods The study of the developed method was carried out in the Matlab Simulink software package. Results A power supply circuit for an electric drive with a synchronized bypass line and a main line with a frequency converter operating according to the developed algorithm is proposed. A study of the influence of the error in measuring the shaft rotation speed on the accuracy of maintaining the recuperation of the DC transformer, as one of the ways to increase the resistance of the VFD to short-term voltage dips in the network was carried out.

Optimal Control of Brushless Doubly Fed Wind Power Generator under Zero-Voltage Ride-Through

In the grid-connected operation dynamics of brushless doubly fed generators (BDFGs), a dip in the grid voltage is equivalent to suddenly adding a reverse voltage source at the parallel node. By deriving the expressions of the transient current of power winding (PW), control winding (CW), and rotor winding (RW) of a BDFG in the complex frequency domain under a natural state, it was concluded that the overshoot and oscillation time are affected by the CW voltage, the drop degree and phase of the grid voltage, and the rotor speed. Therefore, an optimal control strategy is proposed. A state model with the CW current as the state variable was constructed using the Pontryagin minimum principle. The finite-time integral value of the square of the electromagnetic torque was set as the objective function to achieve the minimum value that could suppress the overshoot and oscillation of the electromagnetic torque, and the optimal CW voltage command value was directly solved to accelerate the convergence of the BDFG’s physical quantities, thereby reducing the amplitude. Finally, the feasibility of the optimal control algorithm was verified using tests on an experimental platform.

Three-phase modified quasi-Z-source AC-AC converter for voltage sag and swell mitigation using improved modulation strategy

Three-phase modified quasi-Z-source AC-AC converter for voltage sag and swell mitigation using improved modulation strategy

Internal Power Balancing of an MMC-Based Large-Scale PV System under Unbalanced Voltage Sags

Internal Power Balancing of an MMC-Based Large-Scale PV System under Unbalanced Voltage Sags

Measured Rare Voltage Sags and Clusters of Sags: Prediction Models Driven by the Intermittence Indices

Measured Rare Voltage Sags and Clusters of Sags: Prediction Models Driven by the Intermittence Indices

Enhanced Power Injection Strategies for Voltage Sag Minimization: Integrating the Maximum Apparent Power of the Converter and the Thévenin Equivalent

Enhanced Power Injection Strategies for Voltage Sag Minimization: Integrating the Maximum Apparent Power of the Converter and the Thévenin Equivalent

A Novel Partitioning Approach in Active Distribution Networks for Voltage Sag Mitigation

A Novel Partitioning Approach in Active Distribution Networks for Voltage Sag Mitigation

Research on the impact of voltage sag characteristics in China on electric vehicle charging: BMW Brilliance Electric Vehicle as an example

Research on the impact of voltage sag characteristics in China on electric vehicle charging: BMW Brilliance Electric Vehicle as an example

A Novel Semisupervised Classification Method for Voltage Sag Based on Virtual Adversarial Mean Teacher Model

A Novel Semisupervised Classification Method for Voltage Sag Based on Virtual Adversarial Mean Teacher Model

A novel cause identification method of voltage sag for auxiliary power quality monitoring

A novel cause identification method of voltage sag for auxiliary power quality monitoring

Gate Voltage Dip as a New Indicator for On-Line Health Monitoring of SiC MOSFETs

Gate Voltage Dip as a New Indicator for On-Line Health Monitoring of SiC MOSFETs

Power oscillations cancellation strategy control of DFIG wind turbine during grid voltage dip

Power oscillations cancellation strategy control of DFIG wind turbine during grid voltage dip

Power oscillations cancellation strategy control of DFIG wind turbine during grid voltage dip

Power oscillations cancellation strategy control of DFIG wind turbine during grid voltage dip

Modified SEPIC DC-DC Converter with Wide Step-up/Step-down Range for Fuel Cell Vehicles

The high efficient buck-boost DC-DC converter with wide step-up/step-down range is the way to solve the issue of voltage matching for commercial fuel cell vehicles with a strong hydrogen-electric hybrid. Based on the conventional SEPIC converter, the negative of one of the capacitors is connected with the negative of the power source to get more energy. A modified SEPIC buck-boost DC-DC converter with the advantages of wide voltage conversion range, continuous input current, common ground, and high conversion efficiency is proposed in this paper, meeting all the requirements of DC-DC converters for commercial fuel cell vehicles. On the basis of the steady-state analysis and comparison, the controller is designed based on the small-signal model. To verify the efficiency of the proposed converter, experimental prototypes are built using Si-based and SiC-based devices respectively. The experimental results show that the proposed buck-boost converter can effectively realize 2/3 times step-down and 5 times step-up. When disturbance and voltage dip occur, the adjust time of the control system is less than 200ms. The controller is verified to be robust and have fast responses. The maximum calculation, simulation and experimental efficiencies all exceed 96%, and the maximum efficiency of the SiC prototype under rated power is 96.1%.

Issues of Power Quality

Abstract: In this modern era, the electricity dependence for domestic, commercial and industrial purposes has been increasing day to day. The non-linear loads associated will leads to some of the power quality issues. Such Power Quality Issues viz., voltage sag, Interruptions, spikes in voltage, fluctuations etc. briefly discussed in this paper.

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.

An Improved Power Quality in a Renewable Energy-based Microgrid System Using Adaptive Hybrid UPQC Control Strategy

Due to its ability to integrate renewable energy, improve energy efficiency, and fortify the power system's resilience, microgrids are widely used as regional energy systems. But these advantages do have certain drawbacks in terms of control and Power Quality (PQ). In order to guarantee the proper operation of equipment that is connected and the system's general health, PQ is crucial in microgrids. For microgrids to operate successfully, governing stratagems in concurrence with front-line power electronics devices bid a firm context to knob PQ challenges like Voltage Sag and Swell, Source/Grid current harmonics, Voltage imbalances, Active and Reactive power compensation etc. Multifunctional systems that can integrate clean energy generation and as well as enhance PQ are necessary to meet the demands of complex loads that have the capability of operating in the situation of an unavailable network grid and power electronics devices, which necessitates the need for clean energy. Hence, this paper provides enactment of an adaptive hybrid control strategy based on an Adaptive Leaky Least Mean Square (AL_LMS) algorithm combined with Fuzzy Logic (FL) to the Unified Power Quality Conditioner (UPQC) in a Solar-PV energy based Microgrid system in improving microgrid power quality. The concert of UPQC is assessed by the conventional PI controller and Fuzzy Logic control with MATLAB/SIMULINK software platform, simulation results are conversed with proportionate studies in improving the PQ by minimizing Total Harmonic Distortion (THD), the Voltage Sag & Swell and the result comparison shows the effectiveness of the Fuzzy Logic in coordination with the AL_LMS algorithm resulting improved power quality within the IEEE Power Quality-519 Standards.