Adjacent Substations Research Articles

Positional protection of transmission systems using Global Positioning System

This paper presents a new technique for the protection of power transmission systems by using the Global Positioning System (GPS) and fault generated transients. In the scheme, the relay contains a fault transient detection system together with a communication unit, which is connected to the power line through the high voltage coupling capacitors of the CVT. Relays are installed at each busbar in a transmission network. These detect the fault generated high frequency voltage transient signals and record the time instant corresponding to when the initial travelling wave generated by the fault arrives at that busbar. The communication unit is used to transmit and receive coded digital signals of the local information to and from the associated relay(s) in the system. At each substation, the relays determine the location of the fault by comparing the GPS time stamps measured locally with those received from the adjacent substations. Extensive simulation studies presented in the paper demonstrate the feasibility of the scheme.

Distribution system planning using branch exchange technique

This paper reports the development of a new algorithm for the planning of radial distribution systems. The algorithm is based on the branch exchange technique. Branch exchange has been applied in two stages-between the elements of the network under each substation, called intrazone branch exchange and between the elements of the networks under adjacent substations, called interzone branch exchange. Intrazone exchange determines the optimum network configuration of each substation and interzone exchange determines the optimum service area of each substation. A complete power flow is required after each successful branch exchange. A new algorithm has also been proposed for the load flow of radial distribution networks. The algorithm is not based on node and branch numbering schemes and can handle multiple number of zones and therefore is particularly suitable for planning environment.

Load Forecasting on the TVA System Par I-Substation Loads

Efficient planning and design of the transmission system depends upon reasonably accurate forecastss of the loads it will serve. Substation load forecasts are prepared by the Tennessee Valley Authority (TVA) 15 years in advance. For the first 5 years, preliminary forecasts are prepared by months using time series analysis, carefully collected information, and judgment. Loads for another 10 years are extended largely on the basis of judgment. These preliminary forecasts are subjected to three critical reviews resulting in necessary modifications. The sum of adjacent substation loads is compared with larger area forecasts.