Power System Dynamic Reliability Evaluation Considering Wind Speed Characteristics And Its Applications In Energy Storage System Sizing

As the global environmental pollution and climate changes are increasing,percentage of increase in electric generation form renewable sources has already become the common trend of the global energy industry.At present,new energy sources represented by wind power are developing on a large scale.However,due to the randomness of the wind speed,the frequency of the grid is vulnerable to be shocked.Due to the limits of the regulation capacity of traditional units,energy loss or wind energy waste will be occurred inevitably during the frequency recovery process,which has an impact on the power system reliability.Ignoring the dynamic regulation processes,the results of traditional reliability evaluation are too optimistic.As a result,the grid will face more severe challenges in practical operation.Including the wind speed characteristic in reliability evaluation makes reliability evaluation results closer to the reality.Furthermore relative proposals and solutions also will be put forward to ensure safe operation of power system.This thesis purposes a further exploration from the aspects of identification model,reliability evaluation and wind energy utilization efficiency improvement for specific wind regime.The thesis makes in-depth exploration and study in the following aspects:1)This paper establishes identification model for analyzing wind speed characteristic and proposes wind turbine output model based on blade element momentum theory.The fractal theory has been introduced to analyze changing principle of wind speed.The power spectral density function has been utilized to analyze the energy distribution in frequency domain.Combining with aerodynamic characteristics and the percentage of turbulent kinetic energy provided by high frequency components,wind speed characteristics have been modeled from the aspects of volatility,mutability and intermittency.Through deep study to the force imposed on blades under singular operation condition,the wind turbine output model has also been proposed with considering mismatch condition between wind speed and rotation speed.According to the real data acquired from wind plant,and after analysis and comparison,the results show that proposed wind turbine output model is more practical.2)This paper proposes dynamic reliability evaluation methods and corresponding reliability indices with considering frequency regulation processes.By learning the frequency control theory,the load frequency control model has been proposed with considering the limits of regulation capacity and ramp rates.Through a thorough study of power shortage and surplus in frequency control processes,dynamic reliability evaluation method and corresponding reliability indices have been proposed.The expected indirect energy not supplied(EIENS)and expected energy not supplied(EENS)have been used to analyze system reliability.The expected energy unnecessary consumption(EEUC)and expected energy not used(EENU)have been used to analyze wind energy utilization efficiency.The impacts of wind power penetration,spinning reserve,ramp rates,governor speed regulation and Load-damping coefficient on dynamic reliability evaluation have also been discussed in this paper.The IEEE-RTS79 is used to verify the proposed models and methods.The results show that proposed reliability evaluation method is feasible and practicable not only perfect system reliability evaluation theory but also provide important information for power system planning and operation.3)This paper proposes storage sizing methods with considering dynamic reliability evaluation and economic analysis.The battery energy storage system(BESS)and conventional generator(CG)coordinated frequency control model has been proposed,after analyzing static frequency characteristic and cooperative relationship between BESS and CG.According to the dynamic reliability features of BESS and CGs coordinated frequency control processes,the cost and benefit analysis has been proposed for the system with BESS integration.The energy capacity and power capacity has been determined for the maximization revenues.4)This paper proposes capacity credit evaluation methods with considering wind speed characteristic.According to the different mismatch degree between wind speed and rotation speed,the blade-element-momentum-theory based wind turbine output model is used to evaluate power output of wind turbine generator.Combined with reliability indices acquired from dynamic reliability evaluation,capacity credit evaluation methods have been proposed with considering wind speed characteristic.The impacts of rotation speed,aerodynamics characteristics and wind speed characteristics on capacity credit evaluation have also been analyzed,the real data are used to verify the proposed models and method.The results show that the proposed capacity credit evaluation model comprehensively analyses the effects of the different wind regimes on capacity credit.