Study On Power System Restoration Decision Considering Wind Power Participation

With the increasing dependence of modern society on electricity,the economic losses and social impacts caused by blackouts are becoming more and more serious.Especially in recent years,major blackouts have occurred frequently,and it is necessary to formulate a black start scheme in advance so that system recovery can be performed quickly and safely in the event of a blackout.The continuous improvement of wind power penetration in power grid brings new opportunities and challenges to power system operation.With the maturity of wind power operation control technology,wind power participation in black start recovery becomes a viable means of restoration control.According to the black start process,this thesis divides wind power into black start into two situations: the wind farm is transformed into a black start power supply and the black start plan is involved.The key issues of wind power participation in black start are discussed,and the mathematical model of the doubly-fed wind turbine and the diesel generator model are studied.In order to explore whether the wind farm can be transformed into a black start power source,the continuous effective output evaluation is carried out,and the feasibility of the wind farm as a black sta rt power source is theoretically verified.In order to enable wind power to participate in black-start recovery smoothly and safely,an opportunity-constrained programming model is established to solve the wind power access volume and to serve the formulation of black-start schemes for wind power participation.After a local power grid blacks out,which has no conventional black-start power source,as a black-start power source the wind farms will effectively speed up the system recovery process.Thus,this paper proposes a self-starting method for wind farms with a small capacity diesel generator as a support power source,and formulates a black-start strategy to recover nearby thermal power units.Some indexes are determined,including the number of starting wind turbines and the capacity of diesel generators by analyzing the effective output of the wind farm and the thermal power auxiliary capacity.Then a supported technology of wind farms as the black-start power source is put forward.Meanwhile,in order to enhance the frequency regulation capability of wind-diesel system,this paper studies the frequency control strategy of the wind turbine in black-start,including the virtual inertial control,variable pitch primary frequency regulation and secondary frequency regulation of doubly fed induction generator(DFIG).Finally,this paper uses PSCAD/EMTDC software to simulate the actual example,which verifies the rationality and validity of the proposed scheme.The large-scale access of new-energy generation brings new opportunities and challenges to the power system restoration.Considering that wind power has the features of small start-up power demand and fast start speed,the safe and stable use of wind power will effectively accelerate the system restoration process.Therefore,it is of great significance to study the participation of wind power black start.In this paper,the black start scheme with wind power participation is studied.Firstly,considering the system frequency adjusting ability and unit climbing ability constraint,this paper proposes a method based on the opportunity constrained programming model to estimate the optimal wind power integration capacity in black start,and further assesses the wind power access timing.Secondly,in order t o make use of the wind power effectively,an optimization method of considering wind power to participate in the black start scheme is proposed.Then,by the time step coordinative optimization of wind power access and load restoration,the optimal black start scheme with wind power participation is worked out.The feasibility and effectiveness of the proposed method are verified by an example of the IEEE39 node system with wind power.