Study On Voltage Control Of Active Distribution Network With Micromesh

With the increasing depletion of fossil energy and the increasing pressure on the environment in the process of fossil energy consumption,it is an inevitable choice for the development of China's energy industry to develop renewable energy.In recent years,the installed capacity of new energy generation such as wind power,photovoltaic and biomass has been expanding,and the penetration of new energy has been increasing.The new energy distributed power supply is mainly connected to the power grid through the power electronic conversion interface(grid connected inverter).Due to the characteristics of small inertia and undamped power electronic conversion interface,the intermittent and random volatility of wind power and photovoltaic power generation,large-scale new energy access changes the network structure and power flow mode of traditional distribution network,which brings great challenges to voltage control and power quality of active distribution network.The virtual synchronizer is a new type of inverter control algorithm,which can make the new energy grid inverter have the external characteristics of the traditional synchronous generator,overcome the shortage of the grid inverter in the aspect of inertia and damping,improve the stability of the new energy generation and improve the quality of the grid connected power generation of new energy generation.Therefore,it is of great significance to explore a voltage control mode of active distribution network based on virtual synchronizer to realize new energy source to access the power grid in a friendly way,which is beneficial to the elimination of large-scale new energy.Aiming at the problem of voltage flicker and power quality caused by large-scale new energy access to active distribution network,this paper focuses on a voltage control method of active distribution network based on virtual synchronizer.The main research work includes:(1)The principle and characteristics of the traditional active distribution network voltage regulation mode are compared and analyzed.The characteristics of the traditional voltage regulation mode are summarized,including shunt capacitor,load voltage regulating transformer,SVC,STATCOM and new energy source grid inverter using droop control.(2)The main circuit topology of the virtual synchronizer and its equivalence with the traditional synchronous generator are analyzed.The mathematical model of the virtual synchronizer and the realization process of the control strategy are given,and the design method of the filter parameters of the virtual synchronizer is given.(3)In the power system transient simulation software EMTDC/PSCAD,a IEEE-13 active distribution network model including microgrid is established.It includes:IEEE-13 distribution network model,microgrid model,grid connected inverter model of photovoltaic and energy storage system,traditional voltage regulation control model,virtual synchronizer control model,and energy storage system model.In the low short circuit,the control effect of the traditional voltage regulation method and the virtual synchronous machine on the voltage is compared,and the effectiveness of the virtual synchronous machine to the voltage regulation.of the active distribution network is verified.The simulation results show that the voltage regulation method based on the virtual synchronizer not only overcomes the shortcomings of the traditional new energy grid connected inverters,but also can better suppress the influence of the power supply fluctuation on the active distribution network voltage.