General model for determining maximum restorable load

Abstract

During power system restoration, the maximum load amount that a substation can pick up at one time is a critical parameter to be determined. Many factors should be considered, such as frequency constraint, transient voltage-dip constraint, steady-state voltage constraint and cold load pickup. This paper proposes a general model for calculating the maximum restorable load amount, in which proper checking methods are presented to deal with these constraints. The average system frequency model is employed to calculate frequency deviation. The transient voltage-dip constraint is dealt with by a fast estimation. Cold load pickup characteristics are addressed according to a simple guideline. And a modified bisection algorithm is proposed to solve the complex problem efficiently with considering constraint margin. The effectiveness is demonstrated by case studies performed on the IEEE 14-bus system and a practical power system in China.