HVDC Setpoint Determination for Voltage Stability

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Solution Overview

Problem

Current HVDC control systems are inefficient and slow to respond to voltage instability and unplanned events in power systems, as they rely on manual operator intervention and do not consider the overall power system performance, leading to potential system breakdowns due to fast load dynamics.

Innovation Solution

A method for determining setpoint parameters for an HVDC link in parallel with an AC transmission corridor using equivalent models to quickly calculate and adjust active and reactive power transfer values, allowing for fast response to changing conditions and mitigating voltage instability, involving obtaining measurements, determining power deficits and surpluses, and simulating line trips to optimize setpoint parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If manual operator intervention is used to change setpoints, then operational simplicity is maintained, but response speed to voltage instability and unplanned events is too slow

Engineering Contradiction:
Improveresponse speedVSAvoidcontrol system complexity
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The control system automatically determines setpoint parameters by itself without manual operator intervention. The setpoint determiner continuously monitors power system conditions and autonomously calculates optimal setpoints for HVDC links, enabling the system to serve itself in real-time decision-making.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system uses real-time measurements from phasor measurement units and power flow data to continuously feedback on system conditions. This feedback loop enables automatic adjustment of setpoints based on current voltage stability and power transfer conditions, eliminating the delay inherent in manual monitoring and adjustment.

Inventive Principle:
Principle #23Feedback

2Adaptability or versatility

If setpoints are kept constant or changed manually on a slow time-scale, then control simplicity is maintained, but ability to respond to fast load dynamics and voltage instability is insufficient

Engineering Contradiction:
Improveadaptability to changing conditionsVSAvoidtime delay in response
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The setpoint parameters are transformed from static, manually-adjusted values into dynamic, continuously-updated parameters. The system calculates setpoints in real-time based on current operating conditions, enabling the HVDC control to adapt rapidly to changing load dynamics and voltage stability requirements.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system performs preliminary calculations of optimal setpoints based on anticipated operating conditions and power flow requirements. By proactively determining setpoints before voltage instability occurs, the system can prevent rather than merely react to problems.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If off-line calculation is used for transfer limits, then conservative safety margins are achieved, but network performance and capacity are limited

Engineering Contradiction:
Improvevoltage stabilityVSAvoidnetwork capacity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system dynamically changes the transfer limit parameters based on real-time operating conditions rather than using fixed, conservative off-line calculated values. By adjusting setpoint parameters according to actual voltage stability margins and power flow conditions, the system can safely operate at higher capacities when conditions permit.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the static, mechanical approach of off-line calculation with a dynamic, computational approach using real-time measurements and automated algorithms. This substitution enables the system to continuously optimize transfer limits based on actual system state rather than predetermined conservative margins.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Ease of operation

If conventional control with constant setpoints is used, then system simplicity is maintained, but voltage stability and overall power system performance are not optimized

Engineering Contradiction:
Improvecontrol operationVSAvoidvoltage stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The control system automatically optimizes voltage stability and power transfer performance without requiring operator expertise in complex stability analysis. The setpoint determiner performs the sophisticated calculations and adjustments autonomously, making advanced voltage stability control as easy to operate as constant setpoint control.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3625867B1Determining setpoint parameters for controlling an HVDC link
Publication Date: 2021.07.14 HITACHI ENERGY SWITZERLAND AG
  • EP3625867B1 patent drawingFigure 1~3
  • EP3625867B1 patent drawingFigure 4~6
  • EP3625867B1 patent drawing

AI summary

It is presented a method for determining setpoint parameters for controlling a HVDC link (10) provided in parallel with a transmission corridor (11) comprising at least one AC line (12a, 12b). The comprises the steps of: obtaining a first set of measurements of a first end of the transmission corridor; obtaining a second set of measurements of a second end of the transmission corridor; determining which one of a first area (5a), connected to the first end of the transmission corridor, and a second area (5b), connected to the second end of the transmission corridor, that has a deficit of active power and which one of the first area and the second area of the transmission corridor that has a surplus of active power; determining a model equivalent, based on a corridor equivalent of the transmission corridor and a generator equivalent of the area operating predominately as a generator; and determining setpoint parameters for the HVDC link based on the model equivalent.