다중 부하의 전압 민감도 특성을 고려한 순간전압강하 평가 방법

Abstract

This paper proposes a voltage sag assessment method considering load voltage sensitivities of consumers. In order to assess the damage of voltage sags on a load, it is essential to assess system voltage sag performance reflecting voltage sensitivity of the load, which is characterized by the magnitude and duration of voltage sags. Voltage sensitivity is generally expressed as a Voltage Tolerance Curve(VTC), and its shape varies depending on the types of loads. However, most of the previous assessment methods have focused on VTC of a rectangular shape, which has a limitation in not reflecting VTC of various shapes. This paper proposes a stochastic assessment method of voltage sags using numerical interpolation to reflect various types of VTCs. In the proposed method, voltage sag frequency is estimated by calculating vulnerable areas for given voltage thresholds, and the duration is evaluated using a probability model based on the historical data of system protection devices. In addition, for diagonal shape VTCs, voltage sag frequency is assessed using the spline interpolation method to reduce the amount of computation. In order to verify the performance of the proposed method, a case study was conducted using the IEEE 30-bus test system. The proposed method can effectively assess voltage sag performance for multiple load points with complex sensitivity curves.