Impacts Of Multi-Infeed HVDC On East China Power Grid Stability

This thesis focuses on the analysis of impacts of multi-infeed HVDC on East China Power Grid stability. The main work is as follows:1. Chapter 1 presents the developing history of HVDC (high voltage direct current) transmission system and the inevitability of multi-infeed HVDC (known as MIDC) system. Based on the definition of MIDC, its classification, characteristics and influence on the stability of existing power grid are introduced. Then the developing trend of MIDC system in the South China Interconnected Power Grid and East China Power Grid is discussed. And some recent researches on the MIDC field are summarized at the end of this chapter.2. Chapter 2 discusses the mathematical models of electromechanical transient simulation. First the steady-state mathematical model of DC converter is derived. Meanwhile the control system of HVDC transmission line is described. Then the response model and detailed model of HVDC as well as their application rules are presented. Some important issues in AC-DC system stability simulation such as the parameters of DC converter transformer model are discussed. At the end of this chapter the classifications of excitation systems and turbine governors are made. Their models are presented and the important parameters that have a great influence on system stability are pointed out. These specifications will act as a main principle in the modeling of East China Power Grid on PSS/E program.3. Chapter 3 introduces the simulation platform of this thesis—the PSS/E program. Then the modules used in normal simulations, i.e. the load flow module, dynamic simulation module and diagram plotting module, are discussed respectively. According to the huge dimension of East China Power Grid, the automatised simulation of PSS/E based on IPLAN programming is put forward. Then the algorithm of the N-1 scanning program for the transient stability of East China Power Grid is discussed in detail as well as some related operations and functions in IPLAN. And the flow diagram of the N-l scanning program is presented.4. Chapter 4 uses the programmed computing and simulation of PSS/E based on IPLAN to analyze the transient stability of East China Power Grid for the year of 2020. The modeling methods and computing principles on PSS/E program are presented. The AC-to-DC interactions and stability of East China Power Grid under severe AC disturbances when 7 HVDC lines terminate in East China are discussed. Based on the results of N-1 scanning, the different areas ofcommutation failure are also classified. By modifying the load model parameters, the latent weakness of East China Power Grid is analyzed as well, and some important conclusions are drawn.