Optimization Design And Research Of Cascade Multilevel Dynamic Voltage Restorer

With the rapid development of science and technology and the expansion of the electric power construction,digital electronics and control technology in the application of the process of industrialization and its application in human life,such as frequency conversion speed regulator,PLC and microcomputer control system for sensitive electrical equipment in use,making electricity users more strict to the requirement of power quality.Accompanied by a large amount of non-linear load characteristics of equipments in power system load weight proportion is increased,the power equipment produced by a large number of harmonic,not only will cause pollution to power grid,a more serious condition also produces the voltage sag and voltage interruption and unbalanced three-phase power system of power quality problems.After statistics,Voltage Sags(Voltage Sags)are the most dangerous power quality problems for load power security,and the power quality problems caused by Voltage drop are over 70% of the total.Although the duration of the dynamic power quality problem is shorter,but the accident causes is not easy to find,processing also is relatively difficult,how to reduce the security hidden danger of voltage sags and economic losses,has become a new challenge to solve the problem of quality of power supply at present.Dynamic Voltage Restorer(Dynamic Voltage Restorer DVR)is a kind of series connection between the system and the load of power adjusting device.This article idea and multilevel dynamic voltage restorer as the research object,through the idea league multilevel technique is applied to dynamic voltage restorer,can improve the level of output voltage,effectively improve the capacity of equipment,and improve the voltage of the output harmonic characteristic,make the DVR device in the treatment of high voltage,large capacity of power system voltage drop issue has incomparable advantages.At present,the DVR has become the most economic and effective to improve the quality of power supply of the power electronic equipment.This article start with the working principle of dynamic voltage restorer as a starting point,analyzes the different topology structure of DVR and advantages and disadvantages,and the detection algorithm of voltage drop and voltage compensation of compensation strategy and control strategy and so on has carried on the optimized design.Identified is given priority to with five level cascade circuit structure,adopting SPWM inverter modulation technology as the core,through the minimum energy optimization compensation strategy,improved dq voltage detection algorithm and control strategy for dynamic voltage restorer of voltage compensation device.Through building simulation model in Matlab/Simulink software to carry on the simple voltage sag detection andcompensation control strategy simulation,can be seen from the experimental results,the design of the DVR device can realize compensation for power grid voltage sags,reduced the loss of active power,effectively prolong the compensation.