MVDC Link Control for Lower-Loss Power Transfer Between MV Feeders
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Solution Overview
Problem
Current power distribution networks face challenges in efficiently transferring power between medium voltage (MV) feeders due to lack of accurate state estimation and optimal power flow (OPF) solutions for distribution systems, particularly in reducing active power losses in MVDC links.
Innovation Solution
A method involving a controller that iteratively adjusts power reference quantities for an MVDC link by changing values one at a time, measuring total active power, and selecting the values that result in the lowest power consumption, allowing for reduced power transfer between MV feeders without performing a full optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If standard optimal power flow (OPF) mathematical optimization is performed to reduce active power losses, then power transfer efficiency is improved, but device complexity and computational requirements increase significantly
Solution Approach 1:
The patent segments the complex OPF optimization problem into multiple simpler sub-problems by iteratively adjusting individual power reference quantities one at a time. Instead of performing a full simultaneous optimization of all parameters, the method divides the optimization into sequential steps where each step modifies only one reference quantity (active power, reactive power, or voltage) while keeping others constant, thereby reducing computational complexity while still achieving loss reduction
Solution Approach 2:
The patent applies partial action by performing only the necessary subset of optimization adjustments rather than a complete exhaustive optimization. The method iteratively adjusts reference quantities only when it benefits loss reduction, and stops when no further improvement is possible or when operational limits are reached, avoiding the computational burden of full optimization while achieving sufficient loss reduction
2Productivity
If full state estimation and OPF optimization are implemented, then power transfer capability is improved, but measurement communication requirements and system complexity increase
Solution Approach 1:
The patent extracts and removes the complex state estimation and full OPF optimization requirements from the distribution system. By using a simplified iterative adjustment method that only requires local measurements and basic power flow calculations, the solution eliminates the need for extensive state estimation algorithms and complex communication infrastructure while still enabling effective power transfer optimization
Solution Approach 2:
The system performs self-service optimization by using locally available measurements and iteratively adjusting reference quantities based on local conditions. The method does not require centralized state estimation or complex communication networks - each controller can independently perform the optimization using local measurements of active power losses and adjust reference quantities accordingly
Data Source
AI summary
A method for transferring power between medium voltage feeders via a direct current link in a power distribution network includes setting an iteration step value for each of a set of power reference quantities of the link, setting an initial value of each reference quantity, iteratively changing values of each reference quantity, and selecting one changed value of the set by: changing a present value of each reference quantity with the set iteration step value into a new value, measuring a total active power at a substation of the power distribution network for each new value, and selecting the new value that provides the lowest measured total active power at the substation. A next iteration is performed with the selected new value as present value for the one of the set of power reference quantities and with the present value for the other of the set of power reference quantities.