Grid Oscillation Analysis via Phase Relationship
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Solution Overview
Problem
Current methods fail to accurately determine whether a grid subsystem is contributing positively or negatively to the stability of oscillations in grid frequency, making it difficult to identify and address instability issues in electrical power networks.
Innovation Solution
By analyzing the phase relationship between oscillations in grid frequency and active power, the method determines if a grid subsystem is contributing to or responding to oscillations, using phasor measurement units to measure and process these quantities, allowing for the quantification of the subsystem's contribution to grid frequency oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods are used to monitor grid frequency, then basic frequency data can be obtained, but the ability to determine whether a grid subsystem is contributing positively or negatively to oscillation stability is insufficient
Solution Approach 1:
The patent segments the grid system into multiple controllable subsystems (e.g., different generating plants or control areas) and individually determines the contribution of each subsystem to grid oscillations. This is achieved by measuring frequency and power oscillations at multiple points and calculating the relative contribution of each subsystem, thereby improving measurement precision for contribution determination while maintaining manageable system complexity through modular analysis.
Solution Approach 2:
The patent implements a feedback mechanism where the measured oscillation characteristics and calculated contribution levels are fed back to control systems. This enables automatic identification of subsystems contributing to instability and triggers appropriate control actions to dampen oscillations, thereby improving the precision of contribution determination and enabling active stabilization without proportionally increasing system complexity.
2Measurement precision
If detailed phase relationship analysis is performed between frequency and power oscillations, then accurate contribution quantification is achieved, but the complexity of data processing and analysis increases
Solution Approach 1:
The patent replaces complex manual or mechanical analysis methods with automated digital signal processing techniques. Specifically, it uses digital measurement of phase relationships between frequency and power oscillations, followed by computational analysis to determine contribution levels. This substitution of mechanical/manual processes with electronic measurement and digital computation achieves accurate contribution quantification while reducing overall system complexity through automation.
Solution Approach 2:
The patent transforms the analysis from examining raw time-domain signals to analyzing frequency-domain parameters and phase relationships. By measuring the phase difference between frequency oscillations and power oscillations, and calculating the relative contribution based on these parameter relationships, the system achieves precise contribution quantification through parameter transformation rather than complex direct measurement.
3Measurement precision
If real-time measurement of frequency and power oscillations is implemented across multiple points, then accurate oscillation characterization is achieved, but the cost and complexity of the measurement system increases
Solution Approach 1:
The patent employs universal measurement devices (such as phasor measurement units or digital frequency meters) that can simultaneously measure multiple parameters (frequency, power, phase) at multiple grid points. These multi-functional devices replace the need for separate specialized measurement systems for each parameter and location, thereby achieving accurate oscillation characterization while reducing overall system complexity and cost through equipment consolidation.
Data Source
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AI summary
A method for determining the contribution of a grid subsystem (12) to oscillations in grid frequency experienced by an external electrical grid (14) in an electrical power network (10). A measurement of grid frequency is taken in the grid subsystem (12) and/or the external electrical grid (14). The measurement(s) of grid frequency can be used to extract oscillations in grid frequency in the grid subsystem (12) and/or the external electrical grid (14). A measurement of active power is recorded on a transmission line (16c) between the grid subsystem (12) and the external electrical grid (14). The phase relationship between the oscillations in grid frequency and the oscillations in active power allows the contribution of the grid subsystem (2) to oscillations in grid frequency in the external electrical grid (14) to be determined.