[[alternative]]Design and Implementation of a Controller for Grid Connected Photovoltaic System

碩士電機工程學系[[abstract]]摘 要 本文提出併網型太陽能轉換系統，其架構包括最大功率追蹤、升壓式轉換器、充電控制器、併聯市電型變流器及相關控制電路。最大功率追蹤的方法是利用滑動模式控制器，控制太陽能電池與負載間的升壓轉換器，追蹤太陽能電池輸出最大功率，將太陽能電池輸出的最大功率用變流器與市電併聯，控制變流器輸出電壓的相位及振幅大小，達到控制變流器輸出實功率及虛功率到市電之目的。輸出實功率的控制電路是以零點偵測訊號配合鎖相電路鎖住市電頻率與相位，再以相移電路得到與市電同步但相位角領先市電的控制訊號。虛功率的控制電路是利用數位電路偵測負載端電壓與市電提供給負載電流的相位差，藉以控制變流器的輸出電壓振幅，即可達到控制變流器輸出虛功率給負載之目的。最後設計電路偵測市電頻率及電壓，在系統運轉過程中遭遇劇烈的電壓變動及頻率偏移時，可即時與系統解聯，達到孤島效應防治之目的。本文電路架構分別以OP電路及微控制器(PIC16F877A)來完成，最大功率追蹤除了用MATLAB模擬外，也以實驗結果證明滑動模式控制器的優越性。併網型的相位與振幅控制達到實功率輸出及虛功率補償之目的，最後完成孤島效應防治及太陽能系統保護等實驗，證明本文提出的併網型太陽能轉換系統有良好的運轉特性。[[abstract]]ABSTRACT This thesis proposes a grid-connected photovoltaic system that consists of a boost converter with maximum power tracking, battery charge controller, inverter, and the required control circuits. A sliding mode controller is designed for controlling the boost converter to output the maximum power from the solar cells. A grid-connected inverter is designed to transform the maximum output power into the load and utility. The real power control is realized using zero-cross and phase-lock circuits that control the inverter output voltage which is phase lead and synchronized with the utility. A digital circuit is used to detect the phase angles of the load voltage and current to control the inverter output amplitude to achieve the reactive power load compensation. A monitor circuit is designed to detect the voltage and frequency variation in the utility. When the photovoltaic system encounters a voltage and frequency deviation, the monitor circuit immediately disconnects the photovoltaic system from the utility to prevent the island effect. The proposed approaches are implemented using OP amplifiers and micro controller (PIC16F877A). Both the simulation and experimental results using MATLAB show the sliding mode controller for maximum power tracking has good performance. The phase and amplitude control experiments achieved real and reactive power control. The island effect experiments demonstrated evidence of the solar cell system protection ability illustrating the proposed grid-connected photovoltaic system has good operating performance