Transmission Network Planning Considering Large Scale Wind Power Penetration

Concentrated penetration of the large-scale wind power has become a major trend for wind power development in China.With the integrating of wind power,large scale wind power's randomness,intermittency and correlation will bring more complex uncertainties to power system.These complex uncertainties with the features including randomness and fuzzy are not only affect the frequency stability and the voltage stability of power system,but also have an impact on power flow distribution in power network,which can bring a series of new problems and challenges to power network planning.Based on the output characteristics of large scale wind farms,the cloud model which analyzes the randomness and fuzzy characteristics of complex uncertainties is built to contribute to the research on the transmission coordinated planning considering wind power penetration,the transmission planning considering the full cost of wind power,the transmission planning considering the available transfer capability of wind power and the transmission risk planning considering wind power penetration.These planning schemes are evaluated on the basis of the indexes using the VIKOR theory.The primarily work and achievements of this dissertation are as follows.(1)The cloud models of the main uncertainties in power network planning considering large scale wind power penetration are proposed.The fluctuation of a wind farm output and multiple wind farm's correlation are mainly studied based on ARIMA-GARCH model and R-Pair Copula model respectively.The cloud theory,which is represented the cloud model with the digital characteristics of the expectation value,entropy and superentropy,is introduced to process and descripe the randomness and fuzzy characteristics of large-scale wind farm output effectively.(2)The transmission coordinated planning model considering large scale wind power penetration is built.The capacities of peak regulation and frequency adjustment of power system are analyzed on the condition that the construction plans of the conventional generators including thermal power,hydro power and nuclear power have been determined in the planning period.Based on this point,both large scale wind power integration and grid planning are taken into consideration together by binding the coupling relationship between wind power construction and transmission network expansion.The transmission coordinated planning model that taking the investment of power network,the construction cost of wind generators and the pollution discharge shadow cost as the target function is proposed on the basis of cloud theory.This model,which is decomposed into a main problem and some sub-problems by using decomposition-coordination method,can guarantee the flexible consumption of wind power in frequency adjustment level and peak regulation level from the aspect of power network planning.(3)Multi-objective transmission network flexible planning model considering the full cost of wind power is built.From the standpoints of the static cost,the dynamic cost and ecological cost,the analysis framework of the full cost is constructed,which is composed of the investment of power network,power loss,power outage cost and environmental benefits of wind power based on shadow price theory.The impacts of uncertainties with randomness and fuzzy on power network in the future planning year are comprehensively considered by the cloud model.The established transmission planning considering the full cost of wind power with flexible constraints is benefical for realizing the economic,reliable and ecological operation of power system under the conditions of complex uncertainties.(4)Multi-objective transmission network flexible planning model considering available transfer capacity of wind power is proposed.Maximum available transfer capacity of wind power is studied to avoid wind curtailment caused by the shortage of transmission capacity from the point of transmission planning.The calculation model of available transfer capacity of wind power is put forward based on the fundamental principle of making full use of the allowance of the transmission lines.The transmission planning with flexible constraints is established in conjunction with the cloud model,which takes the cloud digital characteristics of the investment of power network and available transfer capacity of wind power as the objective function.It is useful to make the planning scheme better to suit for the future power environment considering wind curtailment by improving the available magin of transmission capacity.(5)Multi-stage and muliti-objective transmission risk planning model considering the integrated wind power is constructed.The expected value,entropy and superentropy of CVaR are defined on the basis of cloud theory and the risk assessment theory.Multi-stage and muliti-objective risk planning with flexible constraints,which takes the cloud digital characteristics of the investment of power network and CVaR of the transmission investment income as the objective function,is built to make the planning shemes in each stage fit the requirements of large scale wind power penetration,load growth and reducing the level of risk.(6)The evaluation method of the transmission planning schemes considering wind power penetration is put forward.The safety assessment of transmission planning schemes is made on the basis of some indexes including the pessimistic minimum load shedding cost,the expected value of available transfer capacity of wind power and WVaR of the transmission investment income,which represents the capacity of resisting safety risk.The national economy indexes based on the full cost are proposed to investigate some economic issues including the social economic benefit brought by wind power.Based on these indexes,VIKOR theory is introduced to rank and analyze the transmission planning schemes,which can help policymakers to consider maximum group utility and minimum individual regret of the planning sheme simultaneously.Analysis on a typical 18-bus system and a real 300-bus system,as well as the comparison between different planning results with or without considering wind power correlation,prove the feasibility and validity of the method proposed in this dissertation.