Power Grid Frequency Response Estimation Without Full PMU Coverage

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Solution Overview

Problem

Current techniques for determining grid frequency response parameters in power grids are limited in accuracy and versatility, especially when Phasor Measurement Units (PMUs) are not available in all parts of the grid, and they fail to account for changes in load and loss power caused by disturbances.

Innovation Solution

A method that processes frequency data to determine response parameters by considering changes in power, including load and loss power, using both active and passive approaches, even without PMU measurements, by computing these changes from voltage measurements and incorporating them into a power swing equation to enhance accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If PMU instrumentation is deployed throughout the power grid to measure frequency and power, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:
Improvefrequency measurement precisionVSAvoidPMU instrumentation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses voltage magnitude measurements as an intermediary to infer power changes. Instead of directly measuring power with PMUs, the system measures voltage magnitudes and uses the relationship between voltage and power to determine the disturbance power, thereby avoiding the need for complex PMU instrumentation at all locations.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the need for physical PMU instruments with a computational approach using the power swing equation. The system substitutes direct power measurement with voltage measurement combined with mathematical modeling to determine frequency response parameters.

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

2Device complexity

If conventional frequency response determination methods are used without considering load and loss power changes, then device complexity is reduced, but measurement precision deteriorates

Engineering Contradiction:
Improveprocessing system complexityVSAvoidfrequency response parameter accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent incorporates feedback by using the measured frequency response to determine the disturbance power, which then feeds into the power swing equation to refine the estimation of frequency response parameters. This iterative approach improves accuracy without requiring complex additional instrumentation.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the approach from directly measuring power to using voltage magnitude as a parameter to infer power changes. By measuring voltage magnitudes before and after disturbance and using the power swing equation, the system determines disturbance power indirectly, improving precision without increasing device complexity.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If active disturbance introduction is used to determine frequency response parameters, then productivity is improved, but object-generated harmful factors increase

Engineering Contradiction:
Improvefrequency response determination speedVSAvoidgrid disturbance impact
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent uses partial action by introducing only the minimum necessary disturbance to excite the frequency response. The system determines frequency response parameters using small, controlled disturbances rather than large-scale grid events, thereby maintaining productivity while reducing harmful effects on the power grid.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4429059A1Processing method and processing system for processing measurements acquired in a power grid, and system comprising a power grid
Publication Date: 2024.09.11 HITACHI ENERGY LTD
  • EP4429059A1 patent drawingFigure 1
  • EP4429059A1 patent drawingFigure 2
  • EP4429059A1 patent drawingFigure 3

AI summary

Processing methods and processing systems are provided which are operative for processing measurements acquired in a power grid (11). The processing system (20) is operative to receive data comprising frequency data, wherein the frequency data represent a grid frequency measured at one or several locations in the power grid (11) in response to a disturbance. The processing system (20) is operative to determine, for at least a part of the power grid (11), at least one response parameter that affects a grid frequency response of at least the part of the power grid (11) to a further disturbance, wherein the at least one response parameter is determined based on changes in power in response to the disturbance.