Deliverable 5.1: HVDC Network Fault Analysis

This first deliverable of Work Package 5 looking at the test environment of HVDC circuit breakers targets HVDC network fault analysis.

This first deliverable of Work Package 5 looking at the test environment of HVDC circuit breakers, targets HVDC network fault analysis. The technical aspects and performance of circuit breakers are essential considerations in the development of an offshore meshed HVDC grid, and the lack of a proven protection strategy and DC circuit breaker technology is currently one of the major challenges. Therefore, the goal of WP 5 is to develop suitable test requirements and a test programme based on fault analysis of multi-terminal HVDC networks, and ultimately, to realize a test circuit based on AC short-circuit generators.

The report is organised into five main chapters. After a general introduction is provided in chapter 1, the following two chapters outline the technicalities of HVDC transmissions and of multi-terminal HVDC networks. Chapter 4 then provides the simulation results along with a descriptive explanation of the characteristics of the presented curves and is followed by the discussion and conclusions.

Deliverable 5.1 identifies the factors determining the fault currents in meshed multi-terminal HVDC networks. This has been done by reviewing the existing technical literature on HVDC network fault behaviour and conducting simulation studies on a benchmark study network.

The effects of network topology, series reactors, fault location, converter blocking, AC network strength and line type on the rate of rise and the magnitude of the fault current were analysed qualitatively. Based on these results, the report establishes 14 concluding remarks ranging from faults caused by a breakdown of the insulation system to the effects of blocked converters.

Overall, Deliverable 5.1 lays the foundation for Work Package 5 and its aim of creating a test program and developing suitable test requirements for circuit breakers by identifying key difficulties in HVDC network systems, in order to create a stable HVDC grid network that can cope with transmission problems without being forced to reset itself and interrupt the supply of power. Identifying the key factors which determine fault currents in meshed multi-terminal HVDC networks is the goal of task 5.1, so that in the long term the research results can be transferred to test circuits for HVDC circuit breakers.