應用粒子群優法設計靜態同步補償器之自調式比例積分控制器

Abstract

靜態同步補償器能改善電力系統負載端電壓，其動作原理是當負載端電壓過高時，靜態同步補償器會吸收系統過多的虛功，降低負載端電壓。反之，當負載端電壓驟降時，則提供系統不足之虛功，使負載端電壓上升，而達到電壓調整的目的。而為了使靜態同步補償器調整系統負載端電壓到達適當的電壓值，則必須仰賴控制器。其中控制器參數的優劣將直接影響靜態同步補償器的穩態特性及暫態響應。傳統控制器之參數通常保持固定，造成在某些工作點之暫態響應並不太理想之情況，有鑒於此，本論文提出以粒子群優法來尋找最佳或近最佳之控制器參數，利用朗吉庫塔法來求得系統動態響應數值解，進而估算能量函數，再依能量函數求得最佳之控制器參數，進而改變控制器的參數，使得靜態同步補償器的暫態響應在各種負載狀況下皆能有快速補償的效果，並且亦有不錯的穩態特性，此控制器稱為粒子群優法自調比例積分控制器。由實驗結果顯示粒子群優法自調比例積分控制器確實能使得靜態同步補償器在各種負載變動情況下，皆能保持令人滿意的暫態響應及穩態特性。

Static synchronous compensator (STATCOM) can be used to provide system with reactive power under low voltage conditions and to absorb the excess reactive power when the load bus voltage is too high. Satisfactory dynamic responses cannot be guaranteed for all possible loading conditions by a conventional STATCOM of which the controller gains are designed based on a particular loading condition and remain fixed in daily operation of the STATCOM. Since the system load changes with time in daily operation, it is essential to adapt the controller gains in real-time based on the measured system load in order to have good dynamic responses all the time. In the dissertation, particle swarm optimization (PSO) self-tuning PI controller is proposed to adapt the controller gains for the STATCOM. An efficient formula is derived to estimate the resistance and inductance of the load. A computer routine based on Runge Kutta method is developed to obtain the numerical solutions of system dynamic equations which are essential for the estimation of particle energy functions in the PSO algorithm. An efficient PSO algorithm is presented to reach an optimal or near-optimal set of STATCOM controller parameters with least energy functions. To demonstrate the effectiveness of the proposed PSO self-tuning PI controller, experiments were conducted for the system with heavy load, medium load, and light load, respectively. It is concluded from the experimental results that satisfactory dynamic responses can be achieved by proposed PSO self-tuning controller under different loading conditions.