- 學位論文
靜態同步補償器之解析式諧波分析及控制器設計
An Analytical Approach to Harmonic Analysis and Controller Design of a STATCOM
摘要
本博士論文首先分析傳統靜態同步補償器(Static Synchronous Compensator, STATCOM)控制器的優缺點，利用對靜態同步補償器輸出功率的靈敏度分析，得知要控制補償器輸出虛功大小時，直接對靜態同步補償器輸出電壓大小作控制，會比對相角作控制來得有效。其次在博士論文中也提出一個基於第一類Bessel函數的解析式諧波分析方法，由諧波分析的結果，可得知在穩態情況下，當調變係數被固定為1.0時，靜態同步補償器輸出電壓的總諧波失真會是最低，本論文利用此結論提出兩個新靜態同步補償器控制器。 本論文所提的第一種新型靜態同步補償器之控制器採用固定調變係數參考訊號，這新靜態同步補償器控制器利用穩態調變係數控制器，使靜態同步補償器之調變係數在其穩態時都固定為1.0，可使靜態同步補償器的輸出電壓和電流諧波降至最低，而且由所提出解析式方法來分析靜態同步補償器的諧波，再和電腦模擬及實驗所得的電壓和電流的諧波頻譜互相比較，可得知在穩態時，固定調變係數的新控制器可使靜態同步補償器輸出電壓和電流維持在最小諧波，而且可觀察到所提新靜態同步補償器控制器透過在暫態時對調變係數的快速調整，可建立出一個快速動態響應的系統，而非常有效率地調整交流系統匯流排電壓。 本論文中所提出第二種新型靜態同步補償器控制器是利用可調變直流電壓參考訊號，而為了要設計靜態同步補償器中電流調整器、直流電壓控制器、和交流電壓控制器之適當參數，本論文發展出一套以極點零點消去法、根軌跡、和極點指定法為基礎的系統設計流程。在穩態情形下，採用此新型控制器的靜態同步補償器因調變係數亦保持在固定常數為1.0，所以變流器產生的電壓和電流諧波失真將會被有效減少。其次，在暫態情形下透過對直流電壓命令的調整，靜態同步補償器輸出之虛功功率可以快速改變，以便來調整交流匯流排電壓。在穩態操作測試、電流參考命令步級改變測試、三相接地故障測試、和負載改變暫態測試情形下的模擬和實驗結果可以驗証所提出新靜態同步補償器控制器的有效性。
並列摘要
Steady-state harmonics and transient performance of the conventional static synchronous compensator (STATCOM) controllers are first investigated. Based on the sensitivity analysis of the STATCOM output power, it is found that the voltage magnitude is more effective than the phase angle in controlling the reactive power output. An analytical approach to harmonic analysis of a STATCOM based on Bessel functions of the first kind is described. Harmonic analysis of the STATCOM using the proposed analytical approach reveals that the total harmonic distortion of the STATCOM output voltage is minimal as the modulation index is fixed at unity at steady state. Based on these results, two new STACOM controllers are proposed in order to achieve both minimal steady-state harmonics and fast transient response. The first STATCOM controller proposed in this thesis is one with a fixed modulation index reference. The modulation index is held constant at unity at steady state by the proposed STATCOM controller in order to minimize voltage and current harmonics. By comparing the voltage and current response curves and harmonic spectra obtained from the analytical approach, the computer simulations, and the experiments, it is concluded that minimal harmonics can be maintained at steady state and fast dynamic responses can be achieved to regulate ac system bus voltage by the proposed STATCOM controller through the fast adjustment of the modulation index during the transient period. In the second proposed STATCOM controller, a variable DC capacitor voltage reference is employed to minimize voltage and current harmonics at steady state and to adjust DC capacitor voltage level and STATCOM output reactive power rapidly during the transient period. A systematic design procedure based on pole-zero cancellation, root locus method, and pole assignment method is developed in order to determine proper parameters for the current regulator, the DC voltage controller, and the AC voltage controller of the STATCOM. With the proposed STATCOM controller, harmonic distortions in the inverter output current and voltage can be reduced when the modulation index is held constant at unity in steady state. In addition, fast adjustment in the STATCOM output reactive power can be achieved to regulate AC bus voltage through the adjustment of DC voltage reference during the transient period. Simulation and experimental results for steady-state operating condition and transient operating conditions for the system subjected to reactive current step changing testing, three phase line to ground fault testing, and load changing testing are presented in order to demonstrate the effectiveness of the proposed STATCOM controller.