Abstract
High-voltage direct current (HVDC) grids are emerging, and their reliability has been an increasing concern for the utilities. HVDC grids are different from typical two-terminal HVDC transmission systems due to the loops in their topology, which makes it difficult to evaluate the reliability by conventional analytical methods. This paper proposes an innovative hybrid method to evaluate the reliability of meshed HVDC grids. First, steady-state models and reliability models are established for the components in HVDC grids, especially for converters and power flow controllers. In the models, virtual buses are introduced to represent the external AC connections to the HVDC grid. Then a hybrid reliability evaluation method is proposed based on an analytical approach and Monte Carlo simulation. One innovation of the paper is the application of an analytical analysis method to accelerate state evaluation in Monte Carlo simulation by skipping unnecessary optimization. The proposed models and methods are verified on two HVDC grids. Test results show that HVDC grids under most failure states (approximately 70%) tend to shed no load except on buses connected to faulted converters, and the application of the analytical method could promote evaluation efficiency significantly.
Highlights
Renewable energy is playing an ever-increasing role in the power systems all over the world.the development of large-scale renewable energy is hindered to a certain extent by the shortage of transmission capacity
Due to loops existing in the topology, the load can be supplied by more than one source in an High-voltage direct current (HVDC) grid, so the demand may still be met once more than one sources are still reachable after failures
This paper has proposed for the first time a reliability evaluation method for densely meshed
Summary
Renewable energy is playing an ever-increasing role in the power systems all over the world. The European HVDC Study Group investigated basic principles to design and operate HVDC grid. Inspired by these studies, range ofbeen research has been on systems [6]. HVDC systems (e.g., [19,20,21]), these methods are not applicable to meshed HVDC grids (especially densely meshed grids [22]). Reliability evaluation is executed reconfiguration, and scheduling of power systems In these cases, reliability evaluation is executed repeatedly, especially when these problems are solved with heuristic algorithms. An HVDC grid is represented by a tuple (N, L, D, C), where N denotes the set of DC buses, L.
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