Research Of Svg Based On The Unbalanced Operating Conditions

The Static Var Generator(SVG)has become a hotspot of reactive power compensation because of its high switching frequency,good control characteristics and low harmonic characteristics.In practical applications,When the SVG was running under unbalanced conditions,then there has be AC negative sequence current and negative sequence voltage,Resulting in compensation device DC side voltage appears even harmonic,AC side of the odd harmonics,thereby affecting the compensation effect of the device,while increasing the loss of equipment,serious may damage the equipment.Firstly,the working principle and working characteristics of SVG are analyzed in this paper.In order to solve the problem of accurate calculation of reactive power under unbalanced operating conditions,an instantaneous power theory is used to establish the system model of static reactive power generator under unbalanced conditions.Secondly,the positive and negative sequence synchronization control strategy of dq coordinate transformation was established,and the control method of current inner loop decoupling and voltage outer loop was designed.The correctness of control strategy under different working conditions was verified by MATLAB / Simulink simulation model.Then,aiming at the problem of equipment compensation ability under unbalanced operating conditions,the influence of the dead zone on the compensation capacity of the stationary reactive power generator was studied.Based on the positive and negative sequence proportional relationship of the compensation current,the quantitative relationship of the equipment compensation capacity is obtained,And the parameters related to the compensation ability are designed.When the system fails or exceeds the reliable operation range of the equipment,the SVG protection control method was adopted to improve the stability of the system and the safety of the compensation equipment.Finally,A control system based on TMS320F28335 digital signal processor was designed,and the corresponding control program was programmed.A set of SVG experimental platform was built by RT-LAB hardware simulation platform.The design and debugging of the system sampling circuit and control circuit are completed.The experimental results verify the correctness of SVG compensation ability calculation method,which has certain reference significance for compensation equipment selection and protection control.