Study On Power System Electromechanical Transient And Electromagnetic Transient Hybrid Simulation

Electromechanical transient program and electromagnetic transient program have long been used respectively to simulate special phenomenon of power systems. However they have difficulties in analyzing some new problems. Hybrid simulation technology combines their respective advantages of these two kinds of simulators. One of the methodologies is to simulate the general large-scale power system in electromechanical transient mode and at the same time the local network or special component in electromagnetic transient mode. In this way, it balances the considerations of the scale, the precision and the speed of power system digital simulation and provides a new approach to study large-scale power system stability and dynamic characteristics.This dissertation focuses on analyzing the basic theory, investigating the model and algorithm, designing and realizing program, building and applying test platform for power system electromechanical transient and electromagnetic transient hybrid simulation. Main contributions and detailed achievements are shown as follows. The effects of different equivalent circuit forms on hybrid simulation interface precision are analyzed. The errors for several kinds of data exchange sequence methods are compared in detail and their effects on power system dynamic simulations are clarified in theory. Further, the theoretical analysis is validated by the simple testing example.Hybrid simulation interface algorithms based on the status quo achievements are proposed and improved in the dissertation. The work is mainly concerned with the following five aspects: (1) While Norton equivalent circuit form is adopted in electromagnetic transient simulator a new algorithm is proposed that directly solves the fundamental frequency complex impedance according to the existent post-difference nodal admittance real matrix. (2) The method and process of equivalent circuit for the two kinds of simulators are presented according respectively to their data formats and solutions. (3) The positive and negativesequence impedances of Thevenin equivalent circuits are normally not identical because of the difference in generators'positive and negative sequence impedances, which contradicts to the elementary solution of electromagnetic transient simulation when it is converted to a-b-c phase space. Thereby a revised algorithm for Thevenin equivalent circuit is proposed to deal with the problem. (4) A new data exchange protocol is presented, which introduces parallel data exchange protocol in steady-state operation to enhance speed and serial data exchange protocol in network topology change to ensure accuracy. (5) A modified algorithm for fundamental frequency data extraction in electromagnetic transient simulator based on the existing Curve Fitting Algorithm is used here, which partially improves the calculation efficiency.Hybrid simulation test platform is designed and developed base on a self-developed electromechanical transient program and electromagnetic transient program. The key problem in program design is solved and moreover the feasibility and correctness of the test scheme are demonstrated by test examples.The function of the test platform is extended and improved and it enlarges the research field and application scope for power system digital simulations. In the dissertation the multi-PC hybrid simulation test is completed through the Myrinet fast communication network. In addition, physical apparatus is connected to electromagnetic transient simulator of hybrid simulation system and it simply and precisely realizes the real-time and closed-loop test among electromechanical transient simulator, electromagnetic transient simulator and physical apparatus.