混合式太陽光發電系統之電力調控技術研究

Abstract

本研究旨在研發混合式太陽光發電系統(Hybrid PV System，簡稱HyPV)之電力調控技術。HyPV係由太陽光電板、蓄電池、負載、與市電構成，將太陽光電板所產生的電力，透過充放電控制，讓蓄電池充放電，然後經由逆變器(Inverter)將直流電轉變成交流電供負載使用。當太陽光發電不足時，控制器(MCU)將系統切換到市電來供應負載。而負載可依使用程度的重要性分成A、B、C三種等級，等級A規劃為優先供電，主要是日常生活中較重要的設備；等級B規劃為次優先供電，主要是蓄能設備；等級C規劃為次要供電，主要是日常生活中較不重要的設備。 本研究主要進行電力調控技術研究，找尋最佳切換時機，以提升系統性能。當系統蓄電池電壓達過放點(48V)時，MCU會將系統切到Grid供電模式，此時若系統在白天操作狀態，蓄電池會同時被太陽能充電，在這時段蓄電池所累積的充電量稱為太陽能暫存電量設定(SB)，當太陽能暫存電量SB達到某一設定值時，系統就會切回PV供電模式，如此可以避免系統於Grid模式與PV模式過度的切換，可延長蓄電池的使用壽命。另外，會做負載分級電力調控策略的規劃，依照供電等級的優先順序，來調控負載A、B、C供電與否，並利用蓄電池的殘留電量(State of Charge，簡稱SOC)與蓄電池充電電流大小(iB)來輔助負載A、B、C等級開關的調控，提升系統能源的使用效率。 最後，本研究也設計了兩項可優化混合式太陽光發電系統的週邊設備，分別為電力線通信開關(Power Line Communication Switch，簡稱PLCS)與Flow Switch，並分別對兩項設備實測，以應用於混合式太陽光發電系統上，可讓系統更易使用，並減少系統的能量損失。

The purpose of this thesis is to develop a power switching control of Hybrid PV System (HyPV). HyPV is composed of solar PV, battery, loads and grid. The power is generated by solar PV and charged to battery. An inverter is used to convert battery DC output power into AC power for AC loads. When solar power of Hybrid PV is insufficient, MCU will switch to grid mode for loads. Moreover, loads are classified into A, B, and C classes. Class A load is for prior demand. It is the most important equipment in daily life. Class B load is for second prior demand. It is the energy storage equipment. Class C load is for secondary demand. It is the less important equipment in daily life. The present study mainly develops power switching control and with the best switch timing for better system performance. When the battery voltage is lower than 48 V , MCU will switch to grid mode. If the system is in the daytime, battery can be charged from solar PV at the same time. In this period, the battery stores solar energy, called temporary solar energy storage (SB). When SB reaches a setting of value, the system will switch back to PV mode. Therefore, it can avoid frequent switches between grid mode and PV mode and extend battery life. In addition, the MCU carries out a power switching control strategy according to load classification of A, B, and C. The MCU also uses State of Charge (SOC) and battery charge current (iB) to assist load A, B, and C switching control. They can improve system performance. Finally, the present study also develop two important components：power line communication switch (PLCS) and flow switch. They can make the system operation more smoothly and efficiently.