Optimal Planning Of Wind-thermal Generation System Considering Sequential Operation Features

The exploitation of renewable energy resources has become a common issue for governments all around the world.It is also an effective way for China to maintain stable and sustainable development and build a moderately prosperous society.In China,as the main renewable energy resource,the exploitation of wind energy has undergone a rapid development.However,large-scale wind power bases are mainly located in less developed areas of China,where the local light load demand severely restricts the consumption level of wind power.On the other hand,most heavy enery conpumed load centers are located far from the wind power bases.As a result,significant amount of wind energy may be curtailed.To cope with this situation,one feasible plan is to build a bundled wind-thermal generation system(BWTGS)such that the thermal generating units(TGUs)can be scheduled to mitigate the volatility of the wind power and alleviate the operation risk of power systems.Under the support in part by the National Natural Science Foundation of China(No.51377178),this thesis researches the optimal planning of a bundled generation system by considering the sequential operation characteristics of multiple wind farms and thermal generating units.The operation flexibility of BWTGS and the TGUs optimal maintenance schedule are also investigated.The optimal planning model of such bundled generation system with one period or multipke periods are developed.In addition,an optimal operation model of BWTGS considering operaion flexibility is proposed and utilized in the planning model.Due to the time-correlation characteristcs of wind power and the wake effect of wind turbines,the wind energy production and the sequential fluctuation of wind power are greatly affected by the layout of wind turbines in the wind farms.This research considers the sequential fluctuation of wind power and how the wind farm complements each other in the optimal planning of multiple wind farms.A bi-objective optimization model is proposed to find the optimal installed capacity of wind farms and the location of wind turbines.The proposed model can optimize the wind power fluctuation under the premise of the wind energy production,and develops the wind power flucutuation risk index to quantify the effect of wind power fluctuation on system operation security.A uniform design based two-stage evolution genetic algorithm is used for the solution of the proposed model.Simulation results show that the proposed model reduces the fluctuation of wind power and raises the operation efficiency of BWTGS.The insufficiency of operation flexibility resource in power system severely limits the effective consumption of wind power.This thesis develops the operation flexibility indices and operation flexibility evaluation method of BWTGS based on the fluctuation probabilistic characteristics of wind power.An optimal operation model is proposed to consider the system operaion flexibility and the sequtional operaition features of BWTGS.Then the proposed operation model is embedded in the optimal planning model of BWTGS as an operation sub-unit.Finally,the optimal planning model of the bundled wind-thermal generation system considering the operation flexibility is proposed.The proposed model enables the consideration of the TGUs with different minimum on/off time.Moreover,simulation results show that the deficiency of the upward flexibility resources is the leading cause limiting the integration of wind power.The operation model or the planning model of BWTGS also incorporates the maintenance of TGUs.Due to the high penetration of volatile wind power in BWTGS,the TGUs have to be scheduled to compensate for the volatility of wind power under poor running conditions.The preventive maintenance of TGUs in BWTGS keeps the equipment in good conditions and increases the overall system reliability level.It is also useful to enhance the system economic efficiency and to extend component life time.To achieve the goal of preventive maintenance,firstly,the generation maintenance schedule(GMS)model for BWTGS based on the wind power sequential probabilistic behavior is proposed.The proposed GMS model minimizes the system operation cost and determines the optimal GMS of TGUs.Secondly,the optimal planning model of BWTGS considering the maintenance of TGUs is developed.The planning model consists of two sub-models: the planning model and the operation simulation model.The planning model is utilized to generate the planning scheme.The operation model calculates the system operation cost by using the BWTGS optimal operation model considering system operaion flexibility under the GMS of TGUs.Simulation results indicate that the maintenance schedule of TGUs mainly depends on the wind power sequential distribution and the reliability variation of TGUs.Moreover,the transmission power varied with the maintenance capacity of TGU can make BWTGS more economical.The large-scale wind power base usually consists of many wind farms,some are in operation and some are under development.Based on the life cycle cost(LCC),an optimal planning model of BWTGS with multiple periods is proposed to determine the optimal planning schemes of BWTGS,such as the planning schemes of wind farms,the layout of wind turbines,and the matched TGUs for each period.The proposed model takes into account the sequential operation features,the operation flexibility,and the TGU maintenance.The solution of the proposed model is conducted in two steps.Firstly,only the wind farms and the matched TGUs for each period are determined,ignoring the layout of wind turbines.Secondly,the planning schemes of BWTGS for each period are obtained by combining the results of the optimal wind turbine layout and the matched TGU planning.Then the operation cost of BWTGS is calculated by the GMS model and the optimal operation model considering system operaion flexibility.Simulation results show that the planning of several wind farms one period a time allows the wind power base to generate more energy with less fluctuation.The consideration of the sequential operation feartures of BWTGS improves the accuracy and economy of the planning results.