Speedup of parallel computing by parareal method in transient stability analysis of Japanese power system

Long computation time is required for transient stability analysis of power systems because it can be expressed as combination of differential and algebraic equations. In order to finish the calculation within a practical amount of time, it is an effective approach that applying Parareal method as one of parallel computing technique to transient stability analysis. In the Parareal method, the accuracy of the result is gradually updated through iterative procedures in combination with rough estimation of entire waveform and detailed calculation for each decomposed time window. Based on the Parareal method, the authors have developed a new stability assessment method by using chaos theory. If an operating point is in unstable region, the trajectory has the chaotic property, “sensitive dependence on initial conditions”. Therefore, it is possible to assess the stability by detecting the convergence characteristics of the estimated waveform at each iterative procedure by the Parareal method. The effectiveness of the proposed method was tested by using IEEJ WEST10 system model.

I. Introduction

Smart grid technology has been focused on worldwide to realize stable power supply under penetrations of renewable energy sources (RES). In Japan, the main target of RES is photovoltaic (PV) generation and its targeted value of installation is 64GW as of 2030. In order to achieve this target value, it is of prime importance to keep transient stability even with the penetration of PV because the transient stability often becomes a dominant constraint to determine maximum transfer capability. In particular, in the 60Hz power system of western Japan, weakly-damped low frequency oscillation is caused by a fault because of the geographical characteristic that being long in the east-west direction. The analysis of this oscillation is important to assess the transient stability.