Study On Optimal Planning Of Distribution Network Under Market Mechanism

With the reform of electric power operation mechanism in China,the power generation,transmission,distribution,selling are gradually separated and a free competition in power market are formed.The establishment of the power market demands higher requirements for the power grid planning.For one thing,the power grid planning will face many uncertain market factors—load development,power supply construction,system power flow change.For the other thing,the users' demands of"economy,security,flexibility and openness"to the power grid need to be met.Therefore,it is of great significance to study the power grid planning in the market competition mechanism.This thesis reviews the research status of section switch,tie line and distributed power supply's switch-in for the distribution network.And on this basis the research on power grid planning under different grid operation modes is carried out.In traditional vertical monopoly mode,according to the power configuration,operation mode and load conditions,the mathematical model and constraint condition of distribution network optimal planning are established which start from the investment,operation economy and power supply reliability.The detailed calculation method of the costs of equipments' equivalent annual construction and maintenance,the loss of users,power outages and the costs of network loss based on DC power flow are given.In the power market environment,starting from the economic interests of the construction side,the operation side and the users,the model of power outage loss has been improved considering the functions of the active load demand side responde mechanism in distribution network N-1 safety and N safety conditions.Considering the electricity price mechanism in market environment,the solution model of costs for network loss has been modified based on power flow tracking method and the calculative method of wheeling cost which is based on MW-km method is given.The collaborative evolutionary genetic algorithm is used to solve the planning model.The encoding way of control variables and the operating method of genetic operators are given.The planning scheme's safety evaluation is carried out with power entropy and overload line proportion in N safety condition.Through the analysis of the actual engineering distribution network system and IEEE33 nodes system,the optimal planning scheme of section switch,tie line and distributed supply's switch-in position of distributed network in monopoly mode and market mechanism is given as well as various indexes comparison.Finally,the work of this thesis is summarized and the research prospect of distribution network optimal planning is presented.