Research Of Frequency Stabilization Strategy After The Active Splitting Of Receiving-end Power Grid

With the rapid development of large-scaled interconnected power system in our country,big changes have taken place in the power grid structure in comparison with the isolated power grid in the past.Large capacity power plant makes up a larger proportion in the power grid,electricity transmission distance is becoming longer and there emerges the imbalance of generating capacity and electricity consumption.As a result,sending-end power grid and receiving-end power grid are formed.Power imbalance would be resulted in receiving-end power grid by disconnection of large capacity power plant or break of transmission line with large power.Frequency and voltage collapse might be arised by the power imbalance in receiving-end power grid.Therefore,emergency control scheme of receiving-end power grid is significantly important.In view of the above problem,frequency stabilization strategy model of receiving-end power grid is put forward by this paper and the emergency control strategy is calculated.First,the optimal frequency strategy control model considering transient angle stability constraints,frequency stability constraints,voltage and frequency characteristic of load and generator's first frequency regulation effect is proposed.Afterwards,equivalent generator under center of inertia is built and the large-scaled differential algebraic equation constraints are simplified.The complexity to solve the problem is reduced.The differential equation constraints are differenced by implicit trapezoidal integration method and the optimization model is solved with interior point method.Finally,frequency stability control strategy of IEEE case9 and Guangdong power grid are calculated.The load shedding scheme is verified in PSD-BPA.Simulation results shows that dynamic characteristics of the local power grid are taken into account effectively in the model.The economy effect of emergency control scheme is improved.Besides,frequency and voltage stability of the receiving-end local power grid are ensured after the active splitting of the power system.Frequency and voltage stability of receiving-end power grid are ensured with the load shedding scheme calculated by the simplified model of frequency stabilization strategy put forward by this paper.Besides,solving speed of load shedding strategy is improved significantly.As a result,the basis of emergency control scheme's real-time calculation is provided.