This paper discusses the expected-security-cost optimal power flow (ESCOPF) problem. The objective of the problem is to minimize the expected total cost of system operation subject to power system constraints and expected security costs. The probabilities of operating in the pre-contingency operating state and the probabilities of operating in all possible post-contingency states are considered. In addition, the ESCOPF problem includes the cost of interrupting customer load and the cost of generator ramping, which may be necessary when a contingency occurs. The solution to the ESCOPF problem gives information regarding the marginal value of spinning reserve and the marginal value of interruptible load. A graphical tool is used to view the problem solution.Index Terms-Optimal power flow (OPF), power system security, preventive control, social-welfare maximization.

No abstract

This paper presents a risk assessment tool for power transformers in central region substations of Provincial Electricity Authority (PEA) by using health index, which is computing from history and condition weighted scores. The maintenance data from 237 power transformers in central region are used to analyze the risk factors' ranking and scores. The weights of the risk factors are assigned by experienced maintenance crews. The risk assessment factors and scores are categorized with equal weight into two parts: the history of the transformer; and the current condition of the transformer. The weighted scores from both parts are calculated to obtain the health index (HI) for the power transformer. The HI is then plotted on a square matrix called the "health-index matrix", which interprets the risk condition for that transformer. The risk assessment method proposed in this paper is applied to three power transformers in different load areas in central region of PEA. The results show that the method successfully detects the risk condition of those transformers. Therefore the proposed method can create an efficient preventive maintenance plans for power transformers in central region of Provincial Electricity Authority.

No abstract

No abstract