一種用於單相光伏並網發電系統的高頻孤島檢測方法

A High Frequency Island Detection Approach Applied in Single-Phase Grid-Connected PV Generation System

孤島檢測在光伏發電系統中是必有的特性。目前孤島檢測的方法有兩種：被動式孤島檢測和主動式孤島檢測。主動式孤島檢測方法需要改變系統給定的參數，這些參數往往影響了並網電流的波形和品質。本文提出了一種新的可用於單相光伏並網發電系統的主動式孤島檢測方法。首先，分析了單相並網逆變器的輸出電壓的頻譜，從而證明瞭注入高頻電流實現孤島檢測的合理性。其次，給出電網的等效模型並且研究了PCC 節點處輸出電壓的頻率特性。然後提出將1kHz 的擾動量注入到並網電流中並給出由鑒相器和鑒幅器組成的孤島檢測框圖。由實驗結果可知，較低頻分量注入方法而言，高頻分量注入的方法既達到了孤島檢測的目標又將並網電流的總諧波失真降至最低。所以該方法有著良好的工業應用前景。

Island detection is a necessary feature of the photovoltaic (PV) generationsystem. Both passive and active anti-island methods exist. Typically,active methods modify a given parameter, which also affect the shape andquality of the injected current. A new active anti-island approach is proposedin this paper, which is suitable for single-phase grid-connected PV system.First, the output voltage of grid-connected inverter spectrum is investigated toprove feasibility. Second, the equivalent model of grid is proposed, and the frequency response of the voltage of PCC point is also investigated. Then,1kHz perturbation component current is selected to be injected into the gridcurrent and the diagram of island detection method is also proposed, whichmainly consists of a phase detector and magnitude detector. From theexperimental results, compared to the low frequency injection, it can be seenthat the proposed high frequency injection achieves the goal of anti-islanddetection and reduce the current distortion to the minimum as well. As aresult, this technique has good industrial application prospect.