Distributed Voltage Regulation in Multi-Terminal HVDC Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multi-terminal HVDC networks face challenges in reliably managing over-voltages and under-voltages without external communication, as existing methods rely on centralized controllers and measurement units, which are not effective in emergency situations.
Innovation Solution
The method involves local DC voltage measurement at each converter station to detect over-voltage or under-voltage conditions, triggering autonomous modification of the DC power set value using a defined power ramp, allowing each station to restore the system to a stable state without external communication, with prioritization and multi-stage detection to ensure efficient and robust voltage regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a centralized DC Grid Master Controller is used to optimize multi-terminal HVDC networks, then the load flow regulation and voltage optimization are improved, but the system reliability deteriorates when communication between the master controller and converter stations fails
Solution Approach 1:
The patent divides the centralized voltage control function into distributed autonomous control at each converter station. Each station independently monitors its local DC voltage and executes voltage regulation actions without relying on the centralized master controller, thereby maintaining system reliability during communication failures while still achieving effective load flow regulation.
Solution Approach 2:
Each converter station is equipped with autonomous voltage regulation capability that allows it to self-monitor local DC voltage conditions and self-correct voltage deviations using its own converter power. This self-service mechanism eliminates dependency on external communication infrastructure for basic voltage stability maintenance.
2Reliability
If the DC voltage band is designed to accommodate worst-case scenarios, then the system can handle extreme voltage fluctuations, but the mean voltage must be reduced which limits the voltage regulation range
Solution Approach 1:
The patent implements dynamic voltage regulation where each converter station continuously monitors local DC voltage and adjusts its power contribution in real-time based on actual voltage conditions. This dynamic response allows the system to maintain mean voltage at optimal levels while still handling extreme fluctuations through rapid autonomous adjustments, eliminating the need for reduced mean voltage design margins.
3Reliability
If converter stations operate autonomously without centralized coordination, then the system reliability during communication failure is improved, but the ability to optimize overall network performance deteriorates
Solution Approach 1:
The patent enables each converter station to make locally optimal voltage regulation decisions based on its own voltage measurements and control objectives. Each station adjusts its converter power to maintain its local DC voltage within specified bands, and this distributed local optimization collectively achieves effective overall network voltage management without centralized coordination.
Data Source
Figure 1~2
Figure 3~4
AI summary
A method (100) for regulating voltage in a multi-terminal HVDC network system (1) is disclosed. The system comprises one or more converter stations (2). The method (100) involves a step (101) of measuring a local DC voltage at each of the participating converter stations (20), a step (102) of detecting an over-voltage condition when the local DC voltage crosses a predefined upper threshold voltage (10) or detecting an under-voltage condition when the local DC voltage crosses a predefined lower threshold voltage (11), a step (103) of triggering modification of an available DC power set value by the said converter station (10) on detection of the over-voltage or the under-voltage condition, wherein the DC power set value is modified based on a defined power ramp of defined steepness and a final step (104) of checking for termination of the modification step (103) when the over-voltage condition or the under-voltage condition no longer persists.