Research On The EMTP-TSP Hybrid Simulation Of Complex AC/DC Interconnected Power System And The Relative Problems

With the process of national grid interconnection in recent years, the object of power system analysis has become large-scale interconnected grid. Besides, more and more HVDC transmissions lines have been built up and operated in domestic grid, which play an important role in long-distance transmission and sub-grids interconnection. These high-power electronic equipments improve the controllability of system dynamics, while the nonlinear quality of these equipments adds to the difficulties of modeling and accurate analysis. However, to investigate various characteristics of HVDC system, it is necessary to build exact simulation model. Difficulties He in that ac-dc hybrid systems are large-scale nonlinear transient systems which include many variables with different physical characteristics so that traditional HVDC quasi-steady model and AC phase model can no longer satisfy the need of exact simulation. So in this dissertation, appropriate modeling method which combines phase modeling and transient modeling is proposed to investigate the behavior of nonlinear devices in large-scale system, for example, commutation failure, self-excited oscillation, harmonic instability, etc, thus provides useful tool for the analysis and developing corresponding control measures in system.This paper summarizes the trends and development of large power system simulation, especial of HVDC. Based on the above, the research work for complex AC-DC system simulation is shown as follows:Based on the hybrid simulation method, Dual-time scale EMTP-TSP hybrid simulation method is proposed. This paper introduces successful theoretical results from parallel computing; multi-rate calculation and system partition thus describes basic principle and algorithm of multi-step hybrid simulation. Moreover, proper improvement is made according to characteristic of ac-dc system, including proper partition of large system, TSP initial value confirm, bilateral data feed between each sub-system, multi-rate computing, pseudo branch, WRM method and so on. At last comparisons are made between the new method and traditional one. This dissertation summarizes research produce about complicated power system modeling and simulating computation, especially on dc equipment composed of nonlinear devices.The primary objective of this thesis is to investigate the actual large-scale system and to update the measure of analyzing the dynamic phenomena, analyzing the various likely problems in the actual system and coming up with the corresponding restrain measure. At first, the dual time scale hybrid simulation technology applicable to the actual system is proposed. Besides, the simulation and analysis platform based on dual time scale and the precise model of the DC system is established in this paper. A lot of phenomena based on the actual South China Power Grid especially the phenomena of commutation failure which has impact on many lines have been studied and analyzed.The dual time scale hybrid simulation calculation strategy applicable to the actual engineering project is proposed, the Electric Mechanic transient simulation platform aimed at the large system and the Electric Magnetic transient simulation platform aimed at the detailed thyristor model are combined and utilize in the complex AC/DC system, and researches are made to study the arithmetic procedure and the data interchange technology. Moreover, the control strategy for multi-tie element-system method is brought forward. The model of FACTS devices are added in the large-scale power system, and investigated in detail. The principle and structure of trans-platform, multi computer group hybrid simulation is proposed.During the modeling of AC/DC system, the calculation of harmonic transfer and the phenomena of harmonic instability of DC facilities is preliminarily investigated. The combination of Electric Mechanic transient analysis and Electric Magnetic analysis based on the fundamental frequency wave is improved.This paper relies on the engineering project of network planning for China South Power Grid, improves the hybrid multi-rate simulation technology, build the hybrid simulation platform. The research results indicate that hybrid simulation is a effective method of disclosing the dynamic phenomena of power system which can provide some consultation for the improving stability and transfer capability of South China Power Grid, and ensuring the safe and reliable operation of power system.