Speed-up method to calculate distribution system security region

Abstract

The calculation speed is critical for the practical application of the distribution system security region (DSSR). This paper proposes a new method to accelerate DSSR calculation. Firstly, the DSSR models are briefly introduced. Secondly, the influence mechanism of the main transformer capacity on the DSSR is observed and analyzed, forming the theoretical basis for simplifying the computation. Thirdly, a speed-up method based on neglecting the main transformer constraints is proposed. The method includes the calculation formula of the main transformer active capacity, forming main transformer active capacities for common distribution systems in China, and a convenient lookup table-based speed-up process. When the main transformer reaches or exceeds this active capacity condition, it is determined that the main transformer constraints can be ignored in the DSSR modeling, thereby simplifying the model and improving calculation speed. Finally, the proposed method is verified by an extended IEEE-RTBS-BUS4 case and a real distribution system case. The proposed method can accelerate the DSSR calculation by 701 times when it is individually used. The method is further integrated with another method, which combines two speed-up methods for the first time. As a result, the solving efficiency is improved by 6.02 times and 7.43 times, respectively, compared to using the two methods individually, which has achieved the best speed-up effect so far. This study finds that common distribution systems in China mostly satisfy the speed-up condition.