Abstract
Switching overvoltages (SOV) are considered a possible source of component failures experienced in existing offshore wind farms (OWFs). The inclusion of sufficiently accurate and validated models of the main electrical components in the OWF in the simulation tool is therefore an important issue in order to ensure reliable switching operations. Transient measurement results in an OWF are compared with simulation results in PSCAD EMTDC and DigSILENT Power Factory. A user-defined model of the vacuum circuit breaker (VCB) is included in both tools, capable of simulating multiple prestrikes during the closing operation. An analysis of the switching transients that might occur in OWFs will be made on the basis of the validated model, and the importance of the inclusion of a sufficiently accurate representation of the VCB in the simulation tool will be described. The inclusion of the VCB model in PSCAD greatly improves the simulation results, whereas little improvement is found in DigSILENT. Based on the transient study it is found that the simulated SOV can be up to 60% higher at the sending end when using the detailed VCB representation compared to the built-in switch, which emphasises the need for accurate representation of the VCB for energisation studies.
Highlights
In offshore wind farms (OWFs) applications, the consequences of component failure are more severe compared to land based wind farms, due to higher repair costs and lost revenue [1]
This paper presents a user-defined model representation of the vacuum circuit breaker (VCB) intended for radial energisation studies in OWFs
It can be concluded that a sufficiently accurate VCB representation is required in the simulation tool in order to predict the Switching overvoltages (SOV) at the platform, whereas the built-in switch can be used if only the SOV at the wind turbines is investigated
Summary
In OWF applications, the consequences of component failure are more severe compared to land based wind farms, due to higher repair costs and lost revenue [1]. The occurrence of multiple prestrikes is a complex matter and difficult to predict, as the generated voltages and currents depend on many factors such as the dielectric and current interruption properties of the VCB, on the surge impedances of the surrounding network, pole scatter, point on wave of closing and so on [8]. This sets up a demand for the inclusion of a sufficiently accurate VCB representation in the simulation tool, capable of taking into account network/circuit breaker interaction during the closing operation.
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