Abstract
This paper proposes a protection method for single line-to-ground (SLG) faults in an ungrounded offshore wind farm with fully-rated converter-based wind turbines. The proposed method uses the unsynchronized current phasors measured by unit protections installed at the connection point of the fully-rated converter (FRC)-based wind turbines (WTs). Each unit protection collects the unsynchronized current phasors from two adjacent nodes and synchronizes them by aligning the positive-sequence current to the same phase angle. The faulted section is identified by comparing the phase angles of the synchronized zero-sequence currents from adjacent nodes. Simulations of an ungrounded offshore wind farm with relay models were carried out using power system computer-aided design (PSCAD)/ electromagnetic transients including direct current (EMTDC).
Highlights
IntroductionThere have been rapid developments and significant momentum in the use of offshore wind farms in the recent years, because wind power provides a source of clean and renewable energy [1,2,3]
There have been rapid developments and significant momentum in the use of offshore wind farms in the recent years, because wind power provides a source of clean and renewable energy [1,2,3].Voltage source converter (VSC)-based high voltage direct current (HVDC) systems have increased in popularity because VSC-HVDC systems are economical for long-distance bulk power transmission.Unlike high-voltage alternating-current (HVAC) systems, the VSC-HVDC transmission system capacity is not limited by the capacitive charging current
This paper proposes a protection method for single line-to-ground (SLG) faults in ungrounded offshore wind farms incorporating Fully-rated converter (FRC)-wind turbines (WTs)
Summary
There have been rapid developments and significant momentum in the use of offshore wind farms in the recent years, because wind power provides a source of clean and renewable energy [1,2,3]. There are many feeder protection methods for offshore wind farms with FRC-WTs, such as overcurrent protection, methods based on directional power and peak current, or impedance protection. The authors of [18] proposed a protection method based on peak current and directional power; the protection system can detect the faulted feeder and faulted feeder section. This paper analyzes the behavior of an ungrounded offshore wind farm in the case of an SLG fault at different locations to evaluate the feasibility of effective fault detection strategies in the grid. In ungrounded offshore wind farms, there are two sources: HVDC and FRC-WTs. it is difficult to use conventional methods for locating SLG faults in ungrounded offshore wind farms.
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