Global Voltage Security Assessment Index for Power Systems
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Solution Overview
Problem
Conventional methods for voltage security assessment in power systems are time-consuming and computationally demanding, making them inefficient for real-time analysis and cost-effective operation security evaluation.
Innovation Solution
A global voltage security assessment index is defined using line sensitivities at individual buses, allowing for fast computation based on power flow analysis and synchrophasor measurements, which identifies problematic regions and calculates reactive power margins, enabling efficient online assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage security assessment techniques (such as P-V curves, V-Q curves, dynamic analysis, static modal analysis) are used, then comprehensive voltage security evaluation can be achieved, but the computational complexity and time consumption increase significantly
Solution Approach 1:
The patent extracts only the essential information needed for voltage security assessment by using a simplified index based on power flow Jacobian matrix elements. Instead of performing comprehensive dynamic or static modal analysis, the invention extracts specific matrix elements (H and N matrices) that directly indicate voltage security status, thereby reducing computational complexity while maintaining assessment accuracy.
Solution Approach 2:
The patent changes the assessment parameters from comprehensive system-wide analysis to localized bus-specific indices. By calculating voltage security indices based on individual bus power flow characteristics and Jacobian matrix elements, the method transforms the problem from a complex global analysis to simpler local calculations that can be performed efficiently for each bus independently.
2Reliability
If traditional operational planning studies with transmission line tripping and load forecast are applied, then voltage security assessment can be performed, but the analysis time becomes excessively long for real-time applications
Solution Approach 1:
The patent performs preliminary calculations by pre-computing power flow Jacobian matrix elements during normal operation. These pre-computed elements (H and N matrices) are stored and can be quickly combined with contingency data without requiring full re-analysis. This preliminary action enables rapid assessment of multiple contingencies by simply combining pre-computed base case data with contingency-specific adjustments.
Solution Approach 2:
Instead of performing complete dynamic or static modal analysis for each contingency, the patent uses partial analysis by calculating only the necessary Jacobian matrix elements required for voltage security assessment. This partial action approach computes only the essential information needed (bus voltage sensitivities and power flow Jacobian elements) rather than进行全面 system analysis, significantly reducing computation time while maintaining assessment effectiveness.
3Productivity
If neural network method, fuzzy-logic method, adaptive bounding method, or case-based reasoning approach are used for on-line voltage security assessment, then real-time assessment capability can be achieved, but the computational demand and system complexity increase
Solution Approach 1:
The patent enables the power system to self-assess its voltage security status using locally available measurement data and pre-computed Jacobian elements. Each bus can independently calculate its voltage security index using its own power flow data and the standardized formula, without requiring complex external processing systems. This self-service approach eliminates the need for sophisticated neural networks or fuzzy-logic systems while achieving real-time assessment capability.
Data Source
AI summary
Systems and methods for global voltage security assessment in power systems are disclosed herein. In one embodiment, a method for assessing voltage security in a power system having a number (i) of buses includes capturing a change in bus voltage and a change in line reactive power for at least some of the buses in the power system, for each of the i number of buses, calculating a voltage assessment index) (Γi) for as follows:Γi=∑jΔQijΔViwhere ΔVi is the change in bus voltage and ΔQij is the change in line reactive power from a connection j over a predetermined period of time. The method further includes assessing a current voltage security status of the power system based on the calculated voltage assessment index (Γi).