Skeleton-network Reconfiguration Strategy For Liaoning Regional Power System

With the strengthening of the power grid and the accelerating development of new energy,the safety of the power grid faces an uncertain factor.In this context,due to natural or man-made reasons,local faults may appear accidentally.If not handled properly,area power outage will appear and even a large range of power outage will be triggered.Blackouts over a long period of time can cause great economic losses and social impact.After the blackout,power system should be restored quickly and reliably.So the black start recovery plan of the power system need to be developed.As the middle stage of the whole restoration process,skeleton-network reconfiguration need to take full advantage of the restored power capacity to establish a stable network frame for power plants and loads.For Liaoning grid,research on black start mainly focused on the feasibility analysis of black start power supply and the check on the black start energizing path in a small scale.Research on skeleton-network reconfiguration of a wide range of power grid is relatively lack.Based on former researches,this thesis studies the skeleton-network reconfiguration of the Liaoning regional power grid.The concrete steps and safety measures of a black start experiment in Liaoning are introduced.Based on the analysis of the experiment,the problems that need to be improved is discovered.Considering the breaker closing phase angle and nonsynchronous three-phase switching,the energizing path switching overvoltage calculation model is established using the PSCAD/EMTDC software.The switching overvoltage calculation model provides calculation results for the optimization goal and help screening the units that do not meet the overvoltage check.Two optimization objectives of unit restarting are established,including overvoltage times of the energizing path and weighted power generation.Considering the operation constrains,the mathematical model of the recovery optimization of the unit is established.The multi-objective optimization problem is transferred to a single objective optimization problem by linear weighting.Then the optimal recovery sequence of the units is solved by the backward algorithm.The model and algorithm is applied to regional power grid in Liaoning.The skeleton-network reconfiguration scheme in Liaoning regional power grid is finally obtained,which provides a rapid and effective support decision making for dispatch staff after blackout.