Study On The Influence Of Power Grid Operation Mode On Wind Power Consumption Of Combined Heat And Power System

The "three north" areas have severe wind power curtailment in winter,and the "thermoelectric coupling" constraints of CHP units are considered to be the reason of wind power curtailment in "Three Norths" area.Based on the optimized dispatch model of the traditional electric-heat combined system,this paper adds the security constraints of power grid and heating network,studies the impact of network security constraints on wind power consumption,and finds other causes of wind curtailment.Aiming at the change of the power grid operation mode,which will cause the change of the power flow and promote the security issue,an optimized dispatch model considering the start and stop of the unit and the switching of the transmission line is established.Analyze the impact of changes in power grid operation mode on wind power consumption,find measures to improve the wind power consumption of the system when the transmission line or unit is switched.First,the analysis method of the wind curtailment mechanism of the electric power system is extended to the combined heat and power system,and the simulation of the traditional optimized dispatch model verifies that the "thermoelectric coupling" constraint of the thermal power unit is the main reason for wind curtailment.Through the addition of power grid and heat network safety constraints and simulation analysis in the traditional optimized dispatch model,it is found that the thermoelectric unit does not run the "limit electricity with heat" during certain wind curtailment periods,wind abandonment is caused by grid safety constraints at this time.And then the mechanism of wind curtailment caused by grid security constraints is analyzed in detail.Second,in view of the failure of thermoelectric unit or thermal power unit will change the system power flow,which may trigger safety constraints and cause changes in wind curtailment,the relationship between the transmission power of the transmission line and the injected power of the node is established by the direct-current power flow method.The optimal scheduling model of the combined electric and heating system considering network security constraints,unit failure and shutdown,standby unit start-up,and electric and heating load loss penalty costs was constructed.Through simulation analysis,the influence of unit start-up and shutdown on wind power consumption is analyzed,and the scheduling strategy to improve the system wind power consumption rate under unit shutdown is studied.Finally,in view of the fact that the switching of the transmission line will change the system power flow,which may lead to safety constraints and cause windcurtailment changes,a branch power calculation method is proposed by using the direct-current power flow method,and a consideration is given to the change of the power grid topology structure.The optimal scheduling model of the combined electric and heating system is established.Through simulation analysis,the impact of transmission line switching on wind power consumption is analyzed,and the scheduling strategy to improve the wind power consumption rate of the system under the change of power grid topology is studied.Studies have shown that when carrying out the optimization dispatch of the combined electric and heating system,the power grid security constraints and the heat grid security constraints need to be considered.The start and stop of the unit and the switching of the transmission line will change the power flow distribution of the power system,and then the wind curtailment of the system may be changed due to the restrictions of the grid security constraints.In the case of unit failure and shutdown,the wind power consumption rate can be increased by starting a standby unit or an electric boiler;in the case of a change in the topology of the power grid,the wind power consumption rate can be increased by adjusting the unit output and investing in other transmission lines.