MV Feeder Restoration Using Temporary Parallel MVDC Switch Closure
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Solution Overview
Problem
In medium voltage networks with multiple feeders and normally open switches in parallel with MVDC links, determining which switches to close and which links to use for fault isolation and restoration is complex, making it difficult to efficiently restore power to isolated feeders while maintaining a radial feeder structure.
Innovation Solution
A method that involves closing multiple normally open switches in parallel with MVDC links and then selectively opening them, based on power flow calculations and loss minimization, to establish multiple synchronous connections during the restoration process, allowing for the determination of the optimal connection to maintain during the restoration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple NO switches are closed to establish synchronous connections for restoration, then the restoration flexibility and power support capability are improved, but the system complexity and difficulty in determining optimal configuration increase
Solution Approach 1:
The patent changes the operational state parameter of NO switches from static (open/closed) to dynamic (temporarily closed for synchronization, then selectively opened). By controlling the timing and sequence of switch operations, the system achieves flexible restoration while managing complexity through parameter optimization rather than structural complexity
Solution Approach 2:
The patent applies preliminary action by temporarily closing multiple NO switches before fault clearance to establish synchronous connections and enable power support. This preliminary configuration allows the system to prepare multiple restoration paths in advance, improving flexibility without permanently increasing system complexity
2Loss of energy
If multiple NO switches are temporarily closed during restoration, then power loss minimization and optimal connection selection are improved, but the operational complexity and control difficulty increase
Solution Approach 1:
The patent implements feedback mechanisms to monitor power flow, voltage, and current conditions during the restoration process. By continuously measuring system parameters and using this feedback to determine which NO switch to open next, the system minimizes power losses while managing operational complexity through automated control decisions rather than manual optimization
Solution Approach 2:
The patent applies partial action by closing more NO switches than ultimately needed for restoration. This excessive temporary action provides multiple synchronous connection options, allowing the system to select the optimal connection that minimizes power losses. The extra switches are subsequently opened, so the complexity is temporary rather than permanent
3Productivity
If the grid transitions to meshed operation temporarily for restoration, then the restoration capability and power exchange flexibility are improved, but the deviation from radial protection concepts and system stability increase
Solution Approach 1:
The patent applies periodic action by temporarily transitioning the grid to meshed operation only during the fault clearance and restoration period. The NO switches are closed temporarily to enable power support and synchronization, then opened to return to radial operation. This time-limited meshed operation provides restoration capability while minimizing the duration of stability risks
Solution Approach 2:
The patent prepares the system in advance by having NO switches available for temporary closure. This preliminary preparation allows the system to quickly transition to meshed operation when needed for restoration, providing a cushion against complete power loss. The pre-configured switches act as a safety buffer that can be activated temporarily without permanently compromising system stability
Data Source
AI summary
A method for restoration of a fault isolation in a medium voltage, MV, network having a plurality of feeders and a plurality of normally open, NO, switches possibly in parallel with MV direct current, DC, links is presented. The method is performed in a control device of the MV network. The method includes closing at least two NO switches in parallel with MVDC links of the plurality of NO switches, being connected to a fault isolated feeder of the plurality of feeders of the MV network, and opening the closed at least two NO switches in parallel with MVDC links except one. A control device, a computer program and a computer program product for restoration of a fault isolation in a MV network are also presented.