A Probabilistic Load Flow Method Considering Transmission Network Contingency

A new method for probabilistic power flow considering transmission network contingency is proposed for the purpose of removing the unrealistic assumptions of conventional analytical PLF techniques. Because any component failure in a transmission network will change the system configuration, the calculation of power flow distribution needs to consider those contingencies. The method proposed in this paper is able to provide a summation of conditional probability of the load flow solutions assuming all network configurations resulted from contingencies have occurred. The proposed method is based on the combination of Cumulant method for probabilistic power flow and Logarithmic barrier interior point method type solution, which is used to estimate the statistics of load flows. By using this method, the exact level of risk can be expressed easily, which is impossible by deterministic philosophy. This method can bring more economical benefits than that of other PLF methods with respect to the costs and risk levels. The method is validated via a real large transmission system - Queensland network, with forced outages of circuits and generating units. More accurate boundary of variables is calculated with this efficient method.