抄録
This paper presents a method for calculating and estimating the parameters of a bus load model in power system stability studies. There are two basic approaches to obtain load voltage characteristics. One is to directly measure the voltage sensitivity of load active power and reactive power at substations or feeders. The other is to build up a composite load model from knowledge of the mix of load class. It is effective to calculate load voltage characteristics by utilizing the feature of both approaches.
The bus load model we propose consists of a load branch with equivalent impedance to the feeders and transformers in the 66kV or 77kV distribution system, reactive power compensation and load, which is composed of three load classes, such as industrial, commercial and residential. The load voltage characteristics are calculated from voltage and current measured at several feeders, where voltage sag due to a fault occurs. The static load voltage characteristics are represented the exponents, and have correlation with temperature. Exponents of load class are calculated from the measured exponents, temperature and load class mix by least-squares method. The validity to be applicable for the estimated exponents by the exponents of load class and the mix of load classes is evaluated. The bus load using this exponents will be adaptable to not-measured bus loads. They will make stability simulation results more accurate.
