Study Of Transmission Adequacy Based On Optimal Power Flow

With the increasing maturity of the electricity market, the power grid has changed gradually from the vertically integrated management to the market system, and the power grid operation has become more complex as well. So the reliability of power grid is more important. The transmission capacity is one of the important limitations to power grid development, the reliability of power grid and the efficiency of power market. The transmission capacity adequacy plays a very important role in modern electric power industry. It affects and restricts the development of power grid. It is of great value to study the transmission capacity adequacy.This paper introduces foreign power company's research on transmission adequacy, such as National Electricity Market Management Company Limited (NEMMCO), The Union for the Co-ordination of Transmission of Electricity (UCTE), Bonneville Power Administration (BPA), Northwest Power Pool (NWPP) and Pennsylvania-New Jersey-Maryland (PJM). Different power sectors have different methods to evaluate transmission capacity adequacy. And the definitions are various at the same time.Based on the research of foreign power grid principle, with the condition of one of province of our country, the method to study transmission capacity has been introduced in this paper. The method is based on optimal power flow. The objective of the method is to make the minimum out-of-limit of all the branches power flow. The objective function of optimal power flow is needed to be amended according to objective assessment. Based on the fmincopf algorithm, which is one of MATPOWER package based on MATPOWER, the optimal objective has been obtained. What is more, the 14-node system is used to identify the accuracy and validity of the program. And validity of the method is proved by one of province power grid. Four groups of indexes are introduced to show the result, i.e. normal load conditions, percentage of out-of-limit in N-1 fault operation condition, line load ratio, and correlation among lines.