Research On Reactive Power Detection Method And Control Strategy For Static Reactive Power Generator

As the conflicts between global economic development and the shortage of energyresources intensify, a new electricity industry challenge was emerged because of theunbalance distribution of natural energy sources in our country. Flexible alternative currenttransmission systems(FACTS) is important to making a reasonable distribution network,the construction of smart gird, the decrease on lines transmission loss and cost. As the newgenerate reactive compensation devices, static var generator(SVG) is a parallel typeequipment which depends on power electronic technology. It can generate thecompensation current which has the same phase and frequency with the grid voltageaccording to the objective reactive power compensation command. The compensationcurrent would flow into the grid to fulfill the compensation purpose. The emergence ofstatic var generator accelerates the pace of constructing smart grids dramatically. And theutilization of this appliance can prevent the collapse under the break down or over voltagesituation. Therefore, this subject has carried an research work for static reactive powercompensator (SVG) compensation system.First of all, the operating principle of SVG has been given based on the equivalentcircuit diagram under the ideal situation and the practical situation with loss. The SVGmathematic model has been set up based on instantaneous reactive power detection theory.And the direct current control strategy and indirect current control strategy was described.Then, different reactive power detection method has been discussed and compared. Thissubject focused on two instantaneous reactive power detection methods:i p iqdetectionmethod, and the dq coordinate transformation detection method. To consider thedisadvantages of open.loop detection system, the detection method based on adaptivetheory has been put forward, which has immunity for interference and the great ability ofself.study. On this basis, the single phase and three phase reactive power detection modelhave been set up with its derivations. Then, the control strategy of double feedbackclose.loop based on dqcoordinate transformation detection method was chosen, which hasa voltage outer feedback and a current inter feedback. According to the theoretical basis, thehardware construction of compensation system was designed. Firstly, the overall designdiagram was given. Then, the TMS320F2407A chip of TI company was chosen as thecontrol core. After the type selection and references calculation of main circuit elements,the signal pre.process circuit was designed. Analyze the PLL phase locking loop technologyand construction diagram, choose SVPWM technology, which can lead to the highest DCvoltage utilization ratio, to dive the inverter circuit to generate the compensation current. Aim at the system loss, the cooling solution and electromagnetic shielding protectionschemes were given. At the last, using MALAB/SIMULINK built up all parts of thecompensation system and whole devices. The running programs of different modules havebeen given. The functional block diagram of PWM generation module has been given. Setthe preferences of system construction reasonable. Then get the simulation results of thewhole system and analyze them. The analysis of the simulation results reveal that the SVGreactive power compensation system has nice performances with high efficiency, which canmaintain the steady and balance of grid system.