Design On A 10kV 4Mvar Cascaded Static Var Generator System

The reactive power in the power system has a great impact on the operation of system.Its flowing in the power grid not only leads to an increase in the active loss of system,but also leads to a decrease in the stability of system.Therefore,the reactive power compensation device is used to compensate the reactive power of the power grid,which is very important to improve the steady state of the transmission network and stability of power grid voltage.Traditional reactive power compensation equipment has certain flaws such as long response time,large volume,narrow adjustment range,etc.Compared with them,Static Var Generator(SVG)developed based on automation control technol ogy and power electronics technology has advantages of fast response,stable reactive power regulation,wide adjustable range,suppression of output harmonics,etc.It has gradually become the research direction of reactive power compensation.The main purpose of this paper is to develop a 10 k V 4Mvar cascading SVG system,which has the ability to compensate reactive power compensation stably and dynamically.The Cascaded Multilever Converter(CMC)is used as the main circuit design.This paper designs a direct current control,which uses the instantaneous value of system output current as reactive power control parameter.Through the analysis and study of the electrical parameters of the system topology,the grid voltage and reactor voltage are introduced as decoupling control based on the dq transform.Therefore it can realize the output reactive current response quickly without steady-state error.The main circuit design of the cascade system is verified by modeling and simulation.In order to solve the problem of bus voltage imbalance on the DC capacitor,this paper designs a double-loop voltage equalization control.It consists of clustered balancing control and individual balancing control.It can realize the bus voltage balance control without considering the number of system cascades,which is verified by simulation.On the basis of simulation verification,through the calculation and design of the hardware parameters of the system,this paper develop s and builds the experimental prototype to operate on actual working conditions.It verifies the effectiveness of the reactive power control and voltage balance control.And it also verifies the practicality and reliability of developed system.