Research On The Method Of Distribution Network Dispatch Considering Shutdown Risk Of Runoff Hydropower Station Under Typhoon

In southeast coastal area of China,a large number of small run-of-river hydropower plants without regulating capacity are integrated to the distribution network,whose power is determined by the natural inflow.The heavy rainfall under typhoon will make small run-of-river hydropower plants’ power greatly increased and full.When the safe and stable operation of the distribution network is affected due to the inability to absorb the electricity of the small hydropower stations,the dispatching personnel will cut off the small hydropower stations,which may lead to the power shortage of the distribution network.Therefore,it is necessary to dispatch the distribution network considering the shutdown risk of small hydropower stations.The existing research mainly considers the economy of distribution network.The power loss of distribution network,unit operating cost and distributed power reduction are taken as the optimization objective.Stochastic optimization,robust optimization and chance constrained programming are used to solve the uncertainty of distributed power output in distribution network.However,the shutdown of small hydropower caused by typhoon disasters will lead to the operation risk of the distribution network,and the above methods cannot guarantee the safety and reliability of the distribution network in extreme scenarios.At present,some scholars have introduced the risk theory into distribution network dispatch.However,most studies only consider the risk of power reduction and voltage exceedance caused by the fluctuation of distributed generation,and less consider the shutdown risk of small hydropower.Therefore,the operation risk assessment method of run-off small hydropower stations under typhoon disasters is presented in this paper,and the dispatching decision method of distribution network based on the risk assessment theory is studied in this paper.The main work is as follows:Firstly,the sutdown risk assessment model of small hydropower under typhoon disaster is established based on the deterministic cutting load model.Considering the operation of small hydropower in distribution network system,the shutdown probability of small hydropower under typhoon disaster is calculated according to the probability distribution of predicted output of small hydropower.Based on the Adaptive Particle Swarm Optimization Algorithm(APSO),the optimal load shedding cost is calculated as the risk consequence of small hydropower station outage.According to the probability and consequence of small hydropower outage,the risk value of small hydropower outage under typhoon disaster is calculated,which lays a foundation for the shutdown risk assessment model of small hydropower under typhoon disaster.Secondly,the shutdown risk assessment model of runoff hydropower station under typhoon disaster is established based on the chance constrained programming cutting load model.Firstly,the shutdown probability of each small hydropower plant is calculated by the Probabilistic Power Flow method according to the probability distribution of the predicted output of each small hydropower plant.Then,the uncertainty factors in the system are considered in the risk consequence calculation,and the chance constraint model with the minimum shedding load as the objective function is established to calculate the risk consequence of each small hydropower shtdown.Finally,the IEEE33-bus system is taken as an example to verify effectiveness of proposed model.Thirdly,the shutdown risk assessment model of small hydropower considering the uncertainty of wind power output under typhoon disaster is established.Firstly,the probability distribution of wind power prediction error in different prediction intervals is fitted according to the historical data of wind power and its corresponding prediction error.Then,according to the predicted value of small hydropower and wind power,Monte Carlo Simulation Method is used to calculate the shutdown probability of small hydropower and the chance constrained average approximation method is used to solve the optimal cutting load of the system after small hydropower outage.Finally,the IEEE33-bus system is taken as an example to verify effectiveness of proposed model.Fourthly,based on the Conditional Value at Risk theory(CVa R),a method of distribution network dispatch considering the shutdown risk of runoff hydropower stations under typhoon disaster is proposed.Firstly,based on the probability distribution of small hydropower and wind power,the typical output scenarios with probability characteristics are obtained through scene generation and scene reduction.Then,CVa R is used to measure the cost of system operation plan in each scenario,and a stochastic optimization model is established for the decision of active shutdown of small hydropower plants and unit output adjustment,Finally,the effectiveness of the model is verified by taking IEEE-33 bus system as an example.