Estimation Of System Inertia Based On High Penetration Wind Power Generation Connected To The Power System

With the depletion of traditional fossil energy,it has become inevitable for new energy generators represented by wind power and photovoltaic to replace traditional fossil energy for power revolution.The replacement of new energy generators by new energy generators can effectively solve a series of environmental problems caused by the shortage of fossil energy and excessive use of fossil energy.The reduction of the inertia of power system results from the replacement of Conventional synchronous power plants by intermittent generation.It poses threats to system stability,so that the inertia of power system should be estimated to ensure that sufficient rotated reserved capacity are supplied to maintain system stability.This paper proposes an online estimation method based on swing equation to estimate inertia of generator after a disturbance.Firstly,in order to find the reason why wind power will reduce the inertia of power system,the model of doubly-fed wind generation was built in DIgSILENT/PowerFactory including turbine model,transmission chain shafting model,induction generator model and the control strategies of rotor side and grid side of doubly-fed induction.Secondly,the process of power system frequency response is analyzed.Including inertia response primary frequency response and secondary frequency regulation.Based on the wind power farm model which was built in DIgSILENT/PowerFactory,the influence of grid connection on system frequency response was analyzed and the conclusion is that the fast response of power electronic equipment is the key factor which the wind turbine can't control kinetic energy which stored in rotors in order to response the frequency of power system.Finally,to provide quantitative data support for better absorption of new energy units and subsequent control strategies of energy storage devices or wind turbines,a calculation method of inertia time constant of power system based on wide-area measurement system was proposed,and the effectiveness of the method was verified by using the three-machine nine-node system built in DIgSILENT/PowerFactory,achieved the objects.