Control Method And Control Characteristics Of Parallel Control Of Power Storage Equipment In Distribution Network

The importance of energy saving and emission reduction makes the research and application of new energy and distributed generations more and more important.The volatility of distributed generation has seriously restricted its large-scale access to the power grid,while energy storage equipment can realize the regulation and control of distributed generation and the peak filling of load.Thus,the permeability of distributed generation in distribution network is improved effectively and the accommodation capacity of distributed generation is enhanced.Power storage system has been considered as one of the most effective methods to solve problems related to the access of distributed generation in distribution network.In this paper,the power storage equipment is connected to microgrid or distribution network through three-phase voltage inverter,and the control strategy adopts virtual synchronous generator control strategy.The relevant studies are as follows:Firstly,the control principle of virtual synchronous generator control strategy is studied.According to the stator voltage equation and rotor motion equation in the mathematical model of synchronous generator,the frequency modulation principle of speed regulator and the regulation principle of exciter in the control strategy of synchronous generator,the control principle of virtual synchronous generator is obtained.The transfer function of frequency response and active power response of virtual synchronous generator is obtained.The influence of its main parameters on the stability and dynamic performance of virtual synchronous generator control is analyzed by transfer function.The relevant conclusions are verified by building simulation examples and hardware experimental circuits.Then,the parallel control strategy of power storage eqiupment,the operating characteristics of inverter in parallel operation including circulation,the distribution of active power and reactive power are analyzed at first,and a soft-starting method of inverter is proposed.Finally,the influence of line impedance on power distribution and the soft start method proposed in this chapter are simulated and verified,and the influence of inertia on power distribution is analyzed experimentally.Finally,the control metheod of power storage equipment under unbalanced situation is studied,the three-phase unbalanced current compensation method is introduced at first,that is,the separated positive and negative sequence current loop control method,and the measurement of voltage and current unbalance and the algorithm of positive and negative sequence detection are also described.Secondly,aiming at the problem of power fluctuation on the DC side of energy storage inverter under power grid voltage unbalance,the causes of power fluctuation on DC side and the influence of unbalanced grid on virtual synchronous generator control strategy and the parallel operation of inverters are analyzed.Finally,the DC power fluctuation suppression strategy of power storage inverter under unbalanced gird circumstance is realized by simulation and hardware experiment,and its effectiveness is verified.