| With the development of the country and society,the demand for electricity in various industries is increasing,and the power quality and stability of the power system are also required higher.Therefore,it is necessary to strengthen the research on the compensation equipment and methods of power grid,to achieve the control of reactive power,harmonics and three-phase unbalance of power grid,to improve the quality of power supply,and to provide a reliable power basis for economic and social development.Because of its high reliability and fast response speed,static var generator(SVG)is more conducive to the compensation of power grid than other power grid compensation devices,and SVG is also suitable for low-voltage distribution network,this paper studies SVG.Firstly,the common problems of reactive power,harmonics and three-phase unbalance in power system are analyzed,and the development of SVG research at home and abroad is explained.The structure and basic principle of static var generator(SVG)are described in detail.The working principle of SVG without loss and loss is compared,and the volt-ampere characteristics of SVG and SVC are analyzed.At the same time,the three-phase instantaneous power theory is introduced,which provides a basis for the next research on current detection methods.Secondly,several common SVG current detection methods are enumerated,and the characteristics of various methods are analyzed.The structure of id-iq-i0 method is simpler and the cost is smaller,so the id-iq-i0 current detection method is selected to be applied in this paper.The voltage and current of power system are usually three-phase asymmetry,which will lead to inaccurate sinusoidal and cosine signals obtained by PLL.In order to apply accurate sine and cosine signals to current detection method,the phase-locked loop is improved,and the single-phase reactive current is detected by instantaneous reactive current phase separation detection method to verify the compensation effect of SVG.At the same time,the control strategy of SVG is introduced.Low-voltage distribution network does not require high accuracy,so hysteresis comparative control method which is more suitable for low-voltage distribution network is chosen.Finally,the simulation model of SVG compensation system is built in MATLAB software.The improved phase-locked loop is applied to current detection method.The A-phase reactive current is detected by phase-split reactive current detection method,and the compensation effect of SVG on power grid is tested.From different perspectives,the operation environment of power system has been improved,and the research results have been further verified. |
