Reactive Power Configuration Scheme of Offshore Wind Power Transmission System by 220UVAC Submarine Cable

In the offshore wind power transmission system(WPTS) through the AC submarine cable(SC), as the scale of the offshore wind farm(WF) gradually increases, the transmission distance of the AC SC continues to increase. Due to the large charging power of the SC, there are many problems in the actual offshore WF connection project, such as excessive reactive power injection at the point of common connection(PCC) of offshore WFs, over voltage and over current carrying capacity along the SC, and over voltage on the high voltage side of the offshore substation. In response to the above problems, this paper establishes a mathematical model for the WPTS by the 220kV AC SCs, and analyses the WPTS based on the principle of layered division of reactive power compensation. Under the condition of voltage and current limitation along the cable, the offshore high voltage reactor(HVR) value of compensation is determined. Onshore high voltage reactor and SVG are installed on land to make the reactive power exchange between the WPTS and the land AC network zero. When the SVG capacity is minimum, onshore HVR value connected to the system is given. Combined with a specific project in China, the recommended reactive power configuration plan is calculated.