Coordinated Multi-Terminal HVDC Control for Voltage Stability
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Solution Overview
Problem
In multi-terminal HVDC systems, uncoordinated local control actions at converter stations can lead to prolonged operation at unstable and uneconomical voltage levels, potentially detrimental to the DC grid, following disruptions or disturbances.
Innovation Solution
A centralized controller receives measurements from multiple units within the HVDC system, identifies disruptions, calculates new set points for converter stations based on steady-state conditions, and transmits these set points to stabilize the system, using optimal power flow techniques to ensure nominal voltage levels and economic operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If converter station local controls attempt to restore power balance by changing DC voltages based on local measurements, then power balance in the DC grid may be achieved at the converter station, but the HVDC system experiences prolonged operation at voltages above or below nominal levels, leading to instability and uneconomical operation
Solution Approach 1:
A centralized control system acts as an intermediary between converter stations, receiving measurements from all stations and coordinating voltage adjustments across the entire HVDC system. This mediator ensures that power balance restoration does not compromise overall voltage stability, preventing prolonged operation at non-nominal voltage levels while achieving reliable power balance.
2Ease of operation
If uncoordinated local control actions are taken at converter stations following a disruption, then each converter station attempts to stabilize its local operation, but the combined individual actions cause the HVDC system to operate at unstable and uneconomical voltage levels
Solution Approach 1:
The patent merges individual converter station control actions into a unified centralized control framework. Following disruptions, the centralized controller coordinates all converter stations simultaneously, ensuring that local stabilization efforts are harmonized with system-wide requirements, thereby maintaining both operational autonomy and system reliability.
Solution Approach 2:
The centralized control system continuously receives real-time measurements from all converter stations and adjusts control setpoints based on system state feedback. This closed-loop feedback mechanism ensures that uncoordinated local actions are corrected by centralized coordination, preventing instability while preserving local operational flexibility.
3Productivity
If converter stations operate independently to restore power balance, then local power balance may be achieved quickly, but the HVDC system remains in an uneconomical operating state with voltages deviating from nominal levels
Solution Approach 1:
The centralized control system performs preliminary coordination before converter stations execute power balance restoration. By pre-calculating optimal voltage adjustments that satisfy both local and system-wide requirements, the system achieves rapid power balance restoration while avoiding uneconomical operating states and energy inefficiencies.
Data Source
AI summary
Multi-terminal HVDC systems and control methods therefore are disclosed. Methods for controlling multi-terminal HVDC systems having a plurality of converter stations may include receiving a plurality of measurements from a plurality of measurement units disposed on the HVDC system, identifying from the measurements a disruption within the HVDC system, monitoring the measurements to identify a steady-state disrupted condition for the HVDC system, calculating a new set point for at least one of the plurality of converter stations, which new set point may be based on the steady-state disrupted condition and the measurements, and transmitting the new set point to the at least one of the plurality of converter stations. In some examples, the HVDC systems may include an HVDC grid interconnecting the plurality of converter stations and a controller communicatively linked to the plurality of measurement units and the plurality of converter stations.