On geographical allocation of primary frequency control reserves in large interconnected power systems

Abstract

In this paper, we propose a simulation-based method for primary control reserve (PCR) reallocation in large power systems, taking into account the variability of renewable energy sources' (RES) in-feed. Our goal is to identify technically feasible pairwise PCR reallocations between generally non-neighboring control areas (CAs). To achieve this goal, we use network snapshots that represent different grid states in terms of topology, conventional generation, and demand. Given a large amount of historical weather data, we apply copula theory to create a reasonable number of synthetic RES in-feed scenarios, which we then combine with the network snapshots. The resulting synthetic snapshots are used to evaluate different PCR allocations based on an N-1 security assessment considering generator outages as contingencies. The secure reallocations are evaluated using as indicator the post-contingency loading of all lines of the network after PCR activation. A key aspect of the proposed method is that it is designed to be tractable for realistic network sizes up to several thousands of buses and lines. We demonstrate how the method can be applied considering the European interconnected system as a case study. We use real network snapshots coming from the European network of transmission system operators for electricity (ENTSO-E), and official weather data to model RES production. With this setup, we perform two investigations: (a) we provide insights on the amount of PCRs that can be securely reallocated between any two CAs in the European system, and (b) we investigate in detail three specific PCR reallocation strategies from Belgium, Spain, and Austria to Switzerland.