The Coordinated Control Of Load,Grid And Source To Reduce Grid Losses With Wind Cluster Integrated

With the rapid development of wind power in China,the power supply has increased,the contradiction between the power supply and demand is eased,but it also brings about new challenges to China's power grid operation.On the one hand,due to the volatility and uncontrollability of wind power,the peak load regulation of power grid is getting more difficult,leading to the prominence of the problem of wind power interconnection and consumption,and the problem of the wind power curtailment.On the other hand,the intermittent,randomness and fluctuation of wind power output as well as its long-distance transmission make the losses of power grid with wind power integration get more prominent,which can be shown in three aspects:1)wind power fluctuations causes the complexity of the characteristics of power grid losses;2)voltage fluctuations by wind power fluctuations causes the complexity of the characteristics of power grid losses;3)the mode of reserve-peak load regulation causes the complexity of the characteristics of power grid losses.Therefore,how to reduce the losses of power grid with wind power integration on the basis of ensuring the consumption of wind power becomes a key problem to be solved,however,the traditional source-grid coordinated control method can no longer meet the needs of loss reduction of grid with wind power integration.In this paper,the influence mechanism of wind power integration on grid losses is studied in deep,and the complexity of the characteristics of grid losses with wind power integration is put forward.The operating characteristics of different active and reactive power equipment are analyzed.On this basis,the loss reduction mode of coordinated control of load,grid and source,and in-depth study of decoupling and coupling coordinated control method of the active power and reactive power is put forward,in summary,this article achieved the following innovative achievements:In dealing with the losses of power grid with wind integration,three aspect,i.e.the active power fluctuation,wind power fluctuation and the reserve-peak load regulation by regular generators are analyzed.Aiming at the grid losses caused by active power fluctuation,the influence mechanism of wind power output level,wind power fluctuation amplitude and wind power fluctuation rate on grid losses is studied.The influence of wind power fluctuation on voltage fluctuation and the influence of voltage fluctuation on grid losses are studied,and the mechanism of grid losses caused by voltage fluctuation is studied.The influence mechanism of wind power level on the grid losses is analyzed concerning the reserve-peak load regulation.Finally,based on the fully differential form of the grid losses formula,the complicated characteristics of the losses of grid with wind power integration is proposed,which is far different from the traditional power grid losses characteristic.Based on the analysis of the operating characteristics of the equipment of load-grid-source,as well as the complexity analysis of the losses of grid with wind power integration above,the loss-reduction control mode of load-grid-source is proposed,which is a foundation of load-grid-source coordinated control method.The difference of control characteristics of the high energy load and the conventional power generator and the wind power forecasting errors at different time scales are analyzed,and the multi-time scale active power losses-reduction control model of load-grid-source is established.The day ahead active control model takes the discrete high energy load as the target,depressing the grid losses caused by the large-scale fluctuation of the wind power,while the intra-day active control takes the conventional generators and continuous high energy load as the target,dissipating the grid losses caused by the randomness of the wind power.Regarding to the model proposed,the simulated annealing-progressive optimality algorithm is proposed,which can obtain the global optimal solution while reduces the computation time.On this basis,the active power losses-reduction control method of load-grid-source is proposed.Aiming at the grid losses caused by voltage fluctuation by wind power fluctuation,a multi-time scale reactive power loss-reduction control model with various reactive power compensation devices is proposed.The day ahead reactive power control model concerns the optimization of the discrete capacitor and reactor,and the transformer tap position,to suppress the voltage fluctuation degree and reduce the grid losses;while optimizing the continuous reactive power compensation equipment such as conventional power supply,SVC/SVG reactive power output intraday to achieve the purpose of the overall optimization of power flow,so as to further reducing the grid losses;and on this basis,the reactive power reduction control method is proposed.Based on the response sensitivity index of the input power(active and reactive)the node on node voltage(amplitude,phase angle),the load-grid-source decoupling/coupling coordinated control criterion is proposed.The two-layer optimization model,i.e.the upper-layer optimization model dealt with active power coordination control,while the lower-level optimization model dealt with the reactive power coordinated control is proposed.The two-layer transmitted each calculation results to each other and the optimization keeps cross-iterative,guaranteeing the active and reactive power coupling optimization of the whole power system can be achieved.Finally,a loss-reduction control method of load-grid-source is proposed,which can effectively reduce the loss of grid with wind power integration.