Abstract
For the study of transient overvoltage (TOV) in an offshore wind farm (OWF) collector system caused by switching off vacuum circuit breakers (VCBs), a simplified experimental platform of OWF medium-voltage (MV) cable collector system was established in this paper to conduct switching operation tests of VCB and obtain the characteristic parameters for VCB, especially dielectric strength parameters; also, the effectiveness of the VCB reignition model was verified. Then, PSCAD/EMTDC was used to construct the MV collector system of the OWF, and the effects of normal switching and fault switching on TOV amplitude, steepness, and the total number of reignition of the VCB were studied, respectively, with the experimental parameters and traditional parameters of dielectric strength of the VCB. The simulation results show that when the VCB is at the tower bottom, the overvoltage amplitude generated by the normal switching is the largest, which is 1.83 p.u., and the overvoltage steepness of the fault switching is the largest, up to 142 kV/μs. The overvoltage amplitude and steepness caused by switching off VCB at the tower bottom faultily with traditional parameters are about 2 and 1.5 times of the experimental parameters under the same operating condition.
Highlights
Large wind farms are moving from land to sea to provide a richer and more stable source of clean energy [1,2]
This paper mainly introduces a reignition modelling method and model verification of vacuum circuit breakers (VCBs) in the offshore wind farm (OWF) collector system, and studies the characteristics of switching transient overvoltage (TOV) in an OWF collector the OWF collector system, and studies the characteristics of switching TOV in an OWF collector system, respectively, with the experimental parameters and traditional parameters of the dielectric system, respectively, with the experimental parameters and traditional parameters of the dielectric strength of VCB
A test platform for a simplified MV cable collection system in OWF that can demonstrate the reignition phenomenon of VCB was constructed, and the parameters of VCB were calculated through experiments to verify the validity of the customized VCB model
Summary
Large wind farms are moving from land to sea to provide a richer and more stable source of clean energy [1,2]. Studies have shown that the high-frequency (HF) overvoltage generated by the frequent switching on and off for VCBs was the main factor causing insulation fault of the transformers [11,12,13]. 2 ofby et al Sci. simulated switching on a no-load transformer and switching off a no-load transformer under a single-phase grounding short-circuit fault in a medium-voltage (MV) collection grid of OWF [14]. Xuezhong Liu et al established a test circuit for the MV cable simulation system of the wind farm calculation platform of power-frequency overvoltage [15].
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