Optimization Dispatch Strategy For Power System With High Penetration Of Wind Power

In order to satisfy the strategic needs of energy sustainable development,renewable energy has developed rapidly and the power systems have been transformed to a new generation of power systems.In the renewable energy power generation technologies,the fastest developing wind power generation are high intermittent and fluctuating.When high penetration of wind power access to the power grid and participate in the system dispatch,there will be more difficulties and challenges in the energy balance control of power grid.Research the power system optimization dispatch method with high penetration of wind power has become the hot topic.This thesis aims at maximizing the utilization efficiency of renewable energies.The net load formed by conventional load and renewable energy is as the dispatching object and the optimal dispatching models and solving methods of power system are discussed.In order to avoid the curtailment of wind power and satisfy the power system net load energy demand with uncertainties,based on the traditional day-ahead power dispatch,the outputs of traditional generators need to ramp up and down to response to the fluctuations of new energies frequently.The frequent power output changes of thermal generators will cause mechanical damage of the generating equipments and affect the safety of system.Even the thermal power units are needed to be transformed and upgraded to meet the system energy balance requirements,which will decrease the operation efficiency of generators and the economy of the system.In this thesis,a power system day-ahead time division dispatch strategy based on the complexity of net load is proposed.This strategy aims at maximizing utilization efficiency of the renewable energies and the dispatch time periods are divided based on the numerical characteristics of the net load.According to the sample entropy theory,the complexity of net load time series is evaluated and calculated.On this basis,the generation mode of thermal generator operation is determined.Thus,the ramp-up/down power of thermal generators is decreased and the participation of the pumped storage is improved.In order to verify the accuracy of the power system time division dispatch results,based on the same operating conditions,this paper adopts the interval number to describe the uncertainty of the net load and sets up an interval model to calculate the range of the optimized dispatch costs.The worst optimization model transformed from then interval model is a bi-level nonlinear programming model,which is difficult to solve.According to nonlinear dual theory,a nonlinear duality method is proposed,which can transform the interior level model to a dual model.Then the internal level and external level model are merged to a conventional optimization model which can be solved by the primal-dual interior point method.Thus the up interval boundary of the optimization objective can be obtained.The optimal dispatch cost can provide unambiguous imformation about the objective function,which can provide references for dispatching decision adjustments.When the penetration of wind power is rising and the installed capacity proportion of traditional thermal power generators is reduced,utilizing the demand-side resources and introducing flexible energy is another effective way to promote wind power consumption and power grid energy balance.In this thesis,the characteristics of battery energy storage are studied based on the experiment data.The operation constraints are studied and discordance risk of battery energy storage is calculated.On this basis,a power system time division dispatch strategy with the participation of battery energy storage is proposed.In the model,the flexible charging and discharging ability help with the adjustment of net load and respond to the stochastic fluctuation of power sources,which can decrease the fluctuation and ramp power of the thermal power outputs and improve the operation economy of the power system.Finally,based on the real network data of Liaoning power grid of China,the reasonability and validity of the proposed model and method applied in the provincial power grid dispatch with a high proportion of renewable energy are verified.