Weak Bus Identification Using Phasor Voltage Stability Indices
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Solution Overview
Problem
Existing methods for detecting voltage instability in electrical power systems are either inaccurate or computationally cumbersome, particularly in real-time assessments, and often require extensive parameters, leading to potential service disruptions and losses.
Innovation Solution
A method and system that determine weak buses in an electrical power system using phasor measurement units to compute voltage stability indices based on real-time voltage magnitude and phase angle measurements, eliminating the need for additional system information by employing a reference phase angle to identify potential voltage instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If model-based solutions using power flow or continuation power flow are used to track PV curve for voltage instability assessment, then voltage instability can be assessed, but the computation becomes cumbersome and inaccurate for real-time assessment
Solution Approach 1:
The patent extracts only the essential measurements (voltage and current phasor values) needed for voltage instability assessment, eliminating the need for extensive system information such as topology, reactive power limits, line impedances, and loading conditions. This extraction approach simplifies the assessment process while maintaining accuracy by focusing on the critical electrical measurements that directly indicate instability.
Solution Approach 2:
The patent replaces complex model-based computational methods (power flow analysis, continuation power flow) with a direct measurement-based approach using phasor values. This substitution eliminates the need for iterative numerical computations and complex system models, enabling real-time assessment with significantly reduced computational burden while maintaining or improving detection accuracy.
2Reliability
If extensive parameters such as voltage and current phasor values, connectivity, network parameters, loading condition, and outages are used for assessing voltage instability, then assessment can be performed, but unavailability or error in computing these parameters leads to inaccurate detection and service disruption
Solution Approach 1:
The patent extracts and utilizes only the essential parameters (voltage and current phasor values) that are directly available from standard monitoring equipment. By eliminating the requirement for extensive additional parameters such as connectivity information, network parameters, loading conditions, and outage data, the system achieves high reliability without compromising assessment accuracy. The phasor values alone contain sufficient information to detect voltage instability.
Solution Approach 2:
The patent enables the voltage instability assessment system to serve itself using only the measurements already being taken for other purposes (voltage and current phasor measurements). The same measurement infrastructure used for basic power system monitoring provides all the necessary information for instability assessment, eliminating the need for separate data collection systems or additional sensors.
3Loss of time
If delay in sensing and engaging counter-measures occurs, then system conditions deteriorate and lead to unwanted collapses or costlier counter measures, but early detection requires accurate real-time assessment
Solution Approach 1:
The patent replaces computationally intensive model-based methods with a direct measurement-based approach using phasor values. This substitution enables real-time computation and immediate detection of voltage instability, eliminating the time delays associated with iterative power flow calculations. The system can sense instability instantly and trigger counter-measures without delay, preventing system deterioration and costly collapses.
Solution Approach 2:
The patent enables preliminary detection of voltage instability by continuously monitoring phasor values and computing instability indices in real-time. By detecting instability early in its development, the system allows operators to engage counter-measures before the system reaches critical collapse points, preventing unwanted system failures and reducing the need for costly emergency interventions.
Data Source
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AI summary
The invention provides, a method for determining one or more weak buses (102, 104, 106, 108, 110, 304, 306) in an electrical power system (100). The method includes computing voltage stability indices (VSIs) corresponding to a plurality of buses (102, 104, 106, 108, 110) in the electrical power system (100) as a function of phasor values associated with the plurality of buses (102, 104, 106, 108, 110) and a reference phase angle corresponding to one of the plurality of buses (102, 104, 106, 108, 110). The phasor values include either (a) voltage magnitude (Vm) and phase angle (δm), both corresponding to the respective bus, or (b) change or a rate of change of the voltage magnitude (ΔVm), and change or a rate of change of the phase angle (Δδm), both corresponding to the respective bus. The method further includes identifying one or more weak buses (102, 104, 106, 108, 110) from the plurality of buses (102, 104, 106, 108, 110) in the electrical power system (100) based on the computed VSIs.