The Design And Simulation Of Distribution Static Synchronous Compensator

The harmonic,reactive and asymmetric current in the power grid seriously threaten the safe operation of the power grid.As a new generation of compensation device,D-STATCOM has attracted wide attention in the field of scientific research and engineering at home and abroad with its excellent performances such as precise,rapid and comprehensive compensation.In this paper,the main circuit structure of D-STATCOM is studied in depth.Firstly,the basic topology structure of D-STATCOM is introduced,and then the topology structure of the main circuit of D-STATCOM is compared.After that,the mathematical model of the main circuit of D-STATCOM is established.A method to calculate the parameters of the main circuit is presented,and the drive circuit and protection circuit of the main circuit switch device is discussed at the same time.After that,two control modes of D-STATCOM are analyzed,which are direct current control and indirect current control strategy,and the detailed design scheme of direct current control mode is given.In the current control strategy,when the grid voltage is distorted,the phase-locked loop PLL in the traditional instantaneous power i_p-i_q detection method can not get the phase voltage phase accurately,resulting in a certain error between the final compensation instruction current and the ideal value.Therefore,in order to avoid the influence of the power grid distortion to the traditional detection method,the PLL circuit is extracted to the accurate positive sequence voltage phase of the fundamental wave.In this section,by improving the traditional method,a new type of fundamental positive sequence voltage extraction module is used to replace the PLL circuit in the traditional method.An improved i_p-i_q detection method is obtained,and a new control strategy is proposed.Finally,based on the parameter selection of the main circuit,the design of the drive protection circuit and the optimization of the control strategy,the MATLAB/Simulink simulation tool is used to build D-STATCOM simulation model,and a physical device running in Inner Mongglia JiNing power grid is created.The simulation and experimental results show that the compensation function of D-STATCOM to the system harmonics,reactive power and three-phase unbalanced current is well.Meanwhile,the improved traditional instruction current detection algorithm which is proposed in the traditional instruction current control strategy is the simulated and compared under the condition of power grid voltage distortion.The simulation and experiment results show that the new control strategy can effectively improve the compensation effect of the current.In addition,the results illustrate the practicability of the design and the feasibility of the new control strategy.