Research On Static Var Compensator Based On Adaptive FBD Control Strategy

With the construction and development of power system transmission lines in China,the transmission distance and capacity of electric energy are increasing rapidly,which makes transmission efficiency and power quality more important in the transmission process.The transmitted reactive power does not participate in the work of the electric equipments,but increases the system loss,resulting in the reduction of voltage level and power factor.And it reduces power quality as well as brings extra economic burden to the transmission process of power system.Therefore,reactive power compensation is needed to reduce the transmission of reactive power.Because the static var compensator(SVC)has the characteristic of fast continuous compensation of reactive power,a SVC device with a capacity of 300kvar is designed at the low voltage bus of the 10/0.4kV substation on the user side of power system in this thesis,based on the principle of reactive power compensation,which is layered partition and local compensation.The working principle of SVC is studied at the beginning of this thesis.And the voltage and current in different wiring forms are calculated and simulated to determine the proper wiring form and determine the capacity of capacitors and reactors.Since the SVC can be regarded as a controllable susceptance branch,it can be used in the design of control strategy for reactive power compensation.Using C.P.Steinmentz theory,the symmetrical component method and the instantaneous reactive power theory,the amount of susceptance to be compensated is calculated to determine how much reactive power to be peovided.However,the ip-i1 operation mode of instantaneous reactive power theory needs multiple coordinate conversions,so that the FBD method with consistent conclusions of ip-iq mothod is used to reduce the calculation cost.The performance of ip-iq and FBD method are limited by low-pass filter,so adaptive filtering algorithm is used,with the advantages of fast response speed and high steady-state accuracy.Then with freescale MK60DN512ZVLQ10 as the core chip,the SVC control circuit is designed,including signal sampling and processing module,thyristor synchronous firing module,human-computer interaction module.And software programs are sesigned to realize the corresponding functions.Finally,the designed SVC device and reactive compensation control strategy are simulated and verified by MATALB/Simulink.A static var compensators based on adaptive FBD control strategy is researched in this thesis,including hardware and software systems.The SVC control circuit is tested under the laboratory environment,which realizes the functions of signal sampling and processing,thyristor synchronous firing pulses generation,keystroke and display,communication between host computer.Simulated by MATLAB/Simulink and compared with the original FBD control strategy,the simulation results of SVC device and control strategy based on adaptive FBD mothed verify that it can accurately and quickly realize reactive power compensation and improve the voltage level and power factor,which proves its effectiveness and feasibility.