Dynamic Programming ― An Effective Method for Obtaining Optimal Switching Device Location in Radial Distribution Networks

摘要

Electric utilities are meant to provide reliable and environmentally acceptable electric service at minimum cost. The generation, transition and distribution system in India have been expanded tremendously since independence. In spite of the storage in installed capacity, the generation systems in our country are very well planned and constructed. The transmission systems are also pretty well planned. However, the transmission network in many parts of the country is not adequate to evacuate power from generating stations. The distribution system in our country has never been planned properly. In view of this, the distribution system account for maximum percentage of energy losses and maximum number of service interruption. It has been estimated that over 80% service interruption due to faults in distribution systems. It is therefore necessary that greater attention and investment be made in distribution system. In any distribution network primary feeders are normally radial in nature. Any fault on the system leads to a major load shading because of above nature. As a result, large networks connected with that feeder may remain in dark resulting a heavy loss production in industries as well as loss of revenue to the supplying system. Electric distribution network are mostly configured as radial for proper coordination. Under normal operating conditions distribution feeder may be frequently reconfigure by opening and closing switches to reduce line losses, improve feeder voltage profile and increase network reliability while meeting all load requirements and maintaining a radial network. These requirements result in a very complicated non-linear optimization problem. Switching devices are used in primary distribution systems for various application such as to improve service reliability, to isolate a fault for reconfiguration management and to configure the network. Switching devices play a key role in reliability of distribution networks and hence selection of an adequate number of switching devices is an important factor in system planning. Switching devices that locate sectionalized faulted branches in power distribution system restrict drastically the extent of disruption caused by long power interruption when properly positioned. Some algorithm and automatic calculation procedures are suggested here for determining the optimum number of switching devices. Using these algorithms optimum solution can be found for radial distribution system. The procedure is based on Bellmann's principle combined with thinning techniques suitable for overhead and underground networks. Thus, reliability consideration has been recognized as an essential part of power system distribution planning, design, operation and control. The objectives of analysis presented in to outline and validate a methodology for optimization of distribution network. The outage cost minimization taking into account the protective scheme applied and reliability aspects are attained.