Abstract
用戶設備所產生的諧波或三相不平衡電流，注入台電系統，造成台電變電 所的電壓失真。此電壓失真率與台電本身的系統阻抗有關。譬如在離峰時 段，系統阻抗高(或在責任分界點的短路電流低)，相同於尖峰時段的注入 電流，在離峰時段所造成的電壓失真卻較尖峰時段嚴重。由於系統阻抗( 或短路電流)因時變化，國內外電力公司遂訂定系統最小短路電流，據以 管制用戶注入系統的諧波或三相不平衡電流。目前台電採用經驗法則訂定 全年最小短路電流值，清大曾予改良，運用統計方式訂定此最小短路電流 值。本論文模擬台灣高速鐵路在各高鐵變電站的負載，根據各站最小短載 所造成的三相電壓最大不平衡率。另模擬台北捷運系統在各線主變電站的 負路電流，估計各站負載，根據各站最小短路電流，訂定各站的諧波失真 率管制值。本論文比較台電及清大的最小短路電流訂定方式，比較此二最 小短路電流訂定方式對於高鐵及捷運的三相電壓不平衡率或諧波失真率管 制值之差異。有關高鐵三相電壓不平衡之研究，本論文，採用台電15分鐘 錶計方式計算平均負載，在高鐵列車的動態瞬時負載模型中，考慮起動電 流，並評估再生煞車、主變電站變壓器型式對台電所造成三相電壓不平衡 率之影響。最後比較清大與台電最小短路電流訂定方式，對於高鐵三相電 壓不平衡率核給值之差異。在北市捷運諧波研究方面，本論文提出簡易模 型，估計列車負載以及轉換器所造成的諧波電流，及評估起動電流及再生 煞車對台電可能產生諧波之影響。最後，比較清大與台電最小短路電流訂 定方式，對於捷運總諧波電流失真率之差異。本論文第二章主要說明台電 與清大對於最小短路電流訂定方式之差異。第三章為估計高鐵行車動態負 載及比較二最小短路電流訂定方式對高鐵三相不平衡管制之影響。第四章 為估計捷運行車動態負載並比較二最小短路電流訂定方式對捷運總諧波失 真率之影響。最後在第五章中，檢討本論文的研究心得，並提出未來研究 發展的方向。 The harmonic or three-phase unbalance current injection into the Taiwan Power (Taipower) system due to customer's nonlinear load can cause the voltage distortion at Taipower's substation. This voltage distortion also varies with the system impedance of Taipower.For example,during the base-load duration, because the system impedance is high (or the three-phase short-circuit current,abbreviated by 3-φ SCC, is low),the injection current can cause a higher voltage distortion than that caused by the same current during the peak-load duration. As the system impedance (or 3-φ SCC)is variational,the power utility has to specify the minimum 3-φ SCC based on which to regulate the harmonic or 3-φ unbalance current injected into the utility system. Presently,Taipower adopts a rule-based approach to specify the yearly minimum 3-φ SCC.For a theoretical soundness, Tsing-Hua University has proposed a statistical approach to the same specification. Our research comprises of two major parts.In the first part,we simulate the traction load of Taiwan high-speed railway (HSR) system which is now under planning.With the load evaluated,we then estimate the maximum 3-φ voltage unbalance factor at each HSR substation on basis of the station's minimum 3-φ SCC specified by the Taipower's rule-based and the Tsing-Hua's statistical approaches respectively. In the second part,we simulate the load of Taipei mass rapid transit (MRT) system,and estimate the harmonic distortion limits to be imposed on each MRT substation .In this estimation,we also uses the minimum 3-φ SCC specified by the Taipower's and the Tsing-Hua's approaches respectively,and compare the impact of these two approaches on the MRT harmonic distortion limits.