Research On The Algorithm And Models For Power System Unified Dynamic Simulation

Power systems unified dynamic simulations is such a digital simulation method in which the electro-mechanical transient, medium-term and long-term dynamic phenomena are united. It is used to study and analyze the dynamic mechanisms, characteristics of serious faults and the stability control measures of large power systems. Focusing on the the algorithm and models for power system unified dynamic simulations, the major work in this dissertation is summarized as follows.Firstly, a new mixed integral algorithm for power system unified dynamic simulations is proposed. Combing Gear algorithm with variable time step and implicit trapezoidal integration with fixed time step, the new algorithm can satisfy the simulation in time scale from serveral seconds to thousands of second, avoiding the existing problems of the low computational efficiency duo to convergency and the complexity in dealing with the discontinuous equations in control systems.Secondly, by using the characteristics of sparse matrix in power system unified dynamic simulations, a serial algorithm based on block matrix and a parallel algorithm integrating with the workload elimition tree of matrix for fast directly solving the linear equation are proposed, which have been implemented in a new linear system solver. Utilizing the same structure among these small blocks of matrix to the symbolic and numerical LU factorization, forward and backward substitution of solving, the algorithm can achieve high computational efficiency, especially in LU factorization phase.Thirdly, a new boiler-turbine coordinated control systems (CCS) model is proposed, which could be applied to power system electro-mechanical transient, medium-term and long-term dynamics simulation. With appropriate parameters, it can be used to simulate several kinds of control modes of CCS, e.g., coordinated control based on boiler following, etc.. According to the practice in China, the application methods of the model of prime mover energy supply system in coal-fired power plants for power system dynamic simulations are analyzed.Fourthly, a new automatic generation control (AGC) model is proposed based on the modeling method of hybrid system, which mainly consists of three parts: calculation of area control error (ACE), simulation of control strategy, and calculation of generating power regulation. Interfacing to the existing models in the power system unified dynamic simulation program, it is capable of simulating not only the three main control modes of AGC for large power systems, e.g., tie line bias frequency control (TBC), but also the widely-used control strategies based on CPS and A standard. It can be used for analysis of such problems in large power system operation as smoothing of active power fluctuation on tie-line, coordination of AGC for multi-area control, etc..Finally, the softeware for large power system unified dynamic simulation is developed with the objective oriented designing in softeware structure and coding. The results from two simulation cases based on large power systems in China show that the proposed algorithm, models and software are effective.