The progressive growing of single-phase photovoltaic (PV) systems makes the Distribution System Operators (DSOs) update or revise the existing grid codes in order to guarantee the availability, quality, and reliability of the electrical system. It is expected that the future PV systems connected to the low-voltage grid will be more active with functionalities of low-voltage ride-through (LVRT) and the grid support capability, which is not the case today. In this paper, the operation principle is demonstrated for a single-phase grid-connected PV system in a low-voltage ride-through operation in order to map future challenges. The system is verified by simulations and experiments. Test results show that the proposed power control method is effective and the single-phase PV inverters connected to low-voltage networks are ready to provide grid support and ride-through voltage fault capability with a satisfactory performance based on the grid requirements for three-phase renewable energy systems.

/pdf/low-voltage-ride-through-capability-of-a-single-stage-single-4z9f6bdqg4.pdf

Low-Voltage Ride-Through Capability of a Single-Stage Single-Phase Photovoltaic System Connected to the Low-Voltage Grid

Low voltage ride-through capability control for single-stage inverter-based grid-connected photovoltaic power plant

Fast and precise voltage sag detection method for dynamic voltage restorer (DVR) application

Power quality is a pressing concern and of the utmost importance for advanced and high-tech equipment in particular, whose performance relies heavily on the supply’s quality. Power quality issues like voltage sags/swells, harmonics, interruptions, etc. are defined as any deviations in current, voltage, or frequency that result in end-use equipment damage or failure. Sensitive loads like medical equipment in hospitals and health clinics, schools, prisons, etc. malfunction for the outages and interruptions, thereby causing substantial economic losses. For enhancing power quality, custom power devices (CPDs) are recommended, among which the Dynamic Voltage Restorer (DVR) is considered as the best and cost-effective solution. DVR is a power electronic-based solution to mitigate and compensate voltage sags. This paper provides a thorough discussion and comprehensive review of DVR topologies based on operations, power converters, control methods, and applications. The review compares the state-of-the-art in works of literature, and comparative study on power quality issues, the DVR principle along with its operation modes, the DVR components, the DVR topologies based on energy storage, the DVR topologies based on single-/three-phase power converters, and the DVR topologies based on control units that have different control processing stages. Furthermore, modified and improved configurations of the DVR, as well as its integration with distributed generations, are described. This work serves as a comprehensive and useful reference for those who have an interest in researching DVRs.

https://www.mdpi.com/1996-1073/13/16/4152/pdf

Dynamic Voltage Restorer (DVR): A Comprehensive Review of Topologies, Power Converters, Control Methods, and Modified Configurations

The basic challenge associated with the design of vehicle suspension system is the attainment of an optimal trade-off between the various design objectives. This study presents the design of proportional-integral-derivative (PID) controller for a quarter-car active vehicle suspension system (AVSS) using evolutionary algorithms (EA) such as the particle swarm optimization (PSO), genetic algorithm (GA) and differential evolution (DE). Each of the EA-based PID controllers showed overall improvement in suspension travel, ride comfort, settling time and road holding from the manually tuned controller and the passive vehicle suspension system. These improvements were, however, achieved at the cost of increased actuator force, power consumption and spool-valve displacement. DE-optimized PID control resulted in the best minimized suspension performance, followed by the GA and PSO, respectively. Frequency-domain analysis showed that all the signals were attenuated within the whole body vibration frequency range and the EA-optimized controllers had RMS frequency weighted body acceleration of the vehicle within allowable limits for vibration exposure. Robustness analysis of the DE-optimized PID-controlled AVSS to model uncertainties is carried out in the form of variation in vehicle sprung mass loading, tyre stiffness and speed.

Evolutionary algorithm-based PID controller tuning for nonlinear quarter-car electrohydraulic vehicle suspensions

Determining the start and end of the voltage sag event is very important for sag analysis and mitigation. There are several detection methods for voltage sags in which sag voltages are usually expressed in the terms of RMS. The RMS method represents one cycle historical average value, not instantaneous value which may lead to long detection time when voltage sag has occurred. This paper will proposed a novel voltage sag detection method based on miss voltage technique. Proper dead-band and hysteresis are used in the method. The actual instantaneous voltage is compared with certain percentage of desired grid voltage and certain percentage of the amplitude of the grid voltage. Through instantaneous value comparison, low instantaneous value of the grid is shielded which overcome the mishandling turnover of voltage sags. The approach is fully described, and the results are compared with other methods for marking the beginning and end of sag, such as RMS value evaluation method and Peak-value method and simulation result provides that the method is efficient and fast and can be used to determine the initiation and recovery of voltage sags accompanied by missing voltage technique.

/pdf/a-novel-detection-method-for-voltage-sags-4zqn7be5dm.pdf

A Novel Detection Method for Voltage Sags

In this study, research and development of automotive active suspensions are reviewed. Structures and models of various automotive suspensions are described. Furthermore, typical commercial products of automotive suspensions are illustrated. Based on the reported studies and development, the authors discus the comparisons between various vehicular suspensions from the aspects of structure, weight, cost, ride comfort, handling performance, reliability, dynamic performance, energy recovery, and commercial maturity. Consequently, it is deduced that electromagnetic active suspensions are the future trend of automotive suspensions due to simple structure, high-bandwidth, accurate and flexible force control, high ride quality, good handling performance, and energy regeneration. At the same time, the issues of future research and development of electromagnetic active suspensions are proposed.

Study of art of automotive active suspensions

By combining the conventional switched-mode power converters with advanced switched capacitor (SC) techniques, a plurality of single-switch current-balancing circuits is developed to drive multiple light-emitting diode (LED) strings in this paper. Compared with the existing current-balancing LED drivers, the proposed drive circuits exhibit their attractive advantages in size and cost efficiency because just one active switch and one magnetic device are required. LED strings' current can be regulated by controlling the duty ratio of the switch in pulsewidth-modulation mode. Both advanced resonant and nonresonant SC methods are introduced to optimize the performance of the proposed LED drivers. The feasibility and theoretical analysis are verified with a 9-W dual-channel nonisolated prototype and a 25-W four-channel isolated prototype.

Single-Switch Multichannel Current-Balancing LED Drive Circuits Based on Optimized SC Techniques

Charging system for electric vehicle and vehicular charging method of electric vehicle

The busbar has been widely used in electrical & electronic industry because of the demand of the high power transition and the rapid development of the busbar technology However, with increasingly demand in building applications, it is needed to be developed for the highperformance and multi-functional busbar This paper introduces the materials used as busbars and then different busbar types are given After that, the busbar model and parameters are discussed Finally, some failure events of the busbar system happened in cities are introduced and the reasons are analyzed, as well as some solutions proposed

Wang Daohong

Papers

A Novel Detection Method for Voltage Sags

Study of art of automotive active suspensions

Single-Switch Multichannel Current-Balancing LED Drive Circuits Based on Optimized SC Techniques

Charging system for electric vehicle and vehicular charging method of electric vehicle

The study on the busbar system and its fault analysis