MVDC Voltage Link Switching for Smooth Grid Islanding
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Solution Overview
Problem
Existing voltage link arrangements between power distribution grids lack controllability and smooth transition capabilities, leading to inefficiencies in power balance, voltage regulation, and islanding operations.
Innovation Solution
A voltage link arrangement utilizing a medium-voltage direct current (MVDC) link and a breaker, operable in three modes (grid connected, semi-island, and island modes) based on operation information from connected grids, allowing for controlled power transfer and isolation, with a control unit managing the switching between modes to minimize transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a voltage link arrangement uses only a breaker for connection/disconnection between distribution grids, then the device complexity is reduced, but the controllability and smooth transition capability between connection states deteriorates
Solution Approach 1:
The voltage link arrangement is segmented into two distinct components: a breaker for rapid connection/disconnection and an MVDC-link for controlled power transfer. This segmentation allows each component to specialize in its optimal function while together providing both simplicity and controllability.
Solution Approach 2:
The system transitions from a static breaker-only arrangement to a dynamic configuration where the MVDC-link can be independently controlled to provide smooth power transfer. The MVDC-link's ability to regulate power flow dynamically enables controlled transitions between connection states.
2Ease of operation
If a voltage link arrangement operates without multiple operational modes, then the ease of operation is improved, but the ability to maintain power balance and voltage regulation deteriorates
Solution Approach 1:
The voltage link arrangement dynamically switches between three operational modes (island mode, parallel operation mode, and transition modes) based on grid conditions. This dynamic adaptability ensures continuous power balance and voltage regulation while maintaining ease of operation through automated mode selection.
Solution Approach 2:
The system changes operational parameters by transitioning between distinct modes of operation. Each mode has specific parameter settings for power flow, voltage levels, and connection states, allowing the system to optimize performance for different grid conditions while maintaining simple operation through automated parameter adjustment.
3Device complexity
If a voltage link arrangement lacks responsive mode switching capability, then the device complexity is reduced, but the loss of time during connection state changes increases
Solution Approach 1:
The MVDC-link is pre-configured and ready for controlled power transfer, allowing rapid transition between connection states. The system performs preliminary setup of the MVDC-link so that when mode switching is required, the transition can occur quickly without extensive reconfiguration time.
Solution Approach 2:
The MVDC-link acts as an intermediary component that facilitates rapid transitions between connection states. By using the MVDC-link as a mediator for power transfer during mode changes, the system reduces transition time while maintaining controlled and smooth power flow.
Data Source
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AI summary
The present invention relates to a voltage link arrangement (100) connectable between power distribution grids (102, 104), the voltage link arrangement comprising: a medium-voltage direct current (MVDC) link (106) connectable to a first power distribution grid (102) and a second power distribution grid (104), and a breaker (108) arranged in parallel with the MVDC-link and connectable to the first power distribution grid and the second power distribution grid, wherein the voltage link arrangement is operable in at least: a first mode where the breaker is closed, a second mode where the MVDC-link is closed and the breaker is open, and a third mode where the breaker and the MVDC-link are open, wherein the voltage link arrangement is responsive to switch between modes based on operation information indicating operation status of at least one of the first power distribution grid and the second power distribution grid.