A Novel Hierarchical/Decentralized AGC Scheme for Power Systems Integrated With Large-Scale Solar Power Plants

As the penetration level of large-scale solar power plants (LSSPPs) in transmission systems increases, their contribution to the stability of networks cannot be overlooked. Theoretically, such resources can be considered akin to traditional power plants in preserving network stability. Moreover, diverse frequency regulation resources exert varying levels of system complexity, capacity, and response speed, thereby posing challenges to appropriate performance automatic generation control (AGC). As a remedy, a new hybrid (hierarchical/decentralized) scheme is proposed to improve the performance of traditional AGC mechanisms in the presence of LSSPPs and utilize maximum potential capability to ensure network stability. First, a new method is employed to calculate the spinning reserve for LSSPPs considering the performance of AGC for traditional power plants, the dynamics of the DC-link voltage in LSSPPs, the critical operating point related to the most severe disturbance, and the load model. Following this, the decentralized AGC system works hierarchically and in parallel with the centralized algorithm to regulate the frequency and tie lines exchange power. Furthermore, a simple and accurate index ( $\Delta P_{IPS\_x}$ ) is provided to estimate the amount of active power changes after the disturbance in an interconnected power system (IPS). The simulation results are conducted in IEEE 39-bus and PST-16 test systems using DIgSILENT PowerFactory software. The simulation results verify the efficacy and performance of our proposed scheme to improve the AGC system performance and system stability.