Group-Based BCU Method for Dynamic Security Assessment
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Solution Overview
Problem
Current power system management systems lack the capability for on-line dynamic security assessment, which is crucial for preventing blackouts and optimizing operational efficiency, due to the high computational burden and inaccuracies in existing methods like the BCU method, particularly in verifying the one-parameter transversality conditions and ensuring the correctness of controlling unstable equilibrium points.
Innovation Solution
The development of a group-based BCU method that bypasses the need for verifying one-parameter transversality conditions by checking the boundary property directly, using a group-based verification scheme and BCU-exit point method to improve the reliability and accuracy of dynamic security assessments and energy margin calculations, allowing for more efficient on-line dynamic security assessments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the traditional BCU method is used for dynamic security assessment, then the stability boundary verification can be performed, but the computational burden is high and the reliability is compromised due to difficulties in verifying one-parameter transversality conditions
Solution Approach 1:
The patent extracts and eliminates the problematic verification step of one-parameter transversality conditions from the BCU method. By removing this complex verification requirement, the method achieves both reduced computational burden and improved reliability, as the core functionality is preserved without the unreliable verification step
Solution Approach 2:
The patent inverts the traditional approach by not requiring verification of transversality conditions. Instead of trying to verify the conditions mathematically, the invention accepts the BCU method's results directly and uses them to define the stability boundary, thereby inverting the problem-solving approach from verification-based to result-based
2Loss of information
If the time-domain approach is used for transient stability analysis, then detailed simulation information can be obtained, but the computation is intensive and time-consuming, making it unsuitable for on-line application
Solution Approach 1:
The patent segments the stability assessment into two parts: using the efficient BCU method for the initial stability boundary definition and classification, then applying detailed time-domain simulation only to borderline cases that require further analysis. This segmentation reduces overall computation time while preserving necessary information quality
Solution Approach 2:
The patent changes the parameter of analysis by using energy function-based metrics and stability boundaries defined by the BCU method, which allow for rapid assessment without requiring full time-domain simulation. This parameter change enables on-line application while maintaining assessment quality
3Productivity
If modern EMS performs only static security assessment, then the computational burden is manageable, but the system cannot assess the ability to withstand credible contingencies and operate closer to stability limits
Solution Approach 1:
The patent performs preliminary dynamic security assessment using the efficient BCU method to identify stable and unstable contingencies before detailed analysis. This preliminary action allows the system to screen out clearly stable cases, enabling operational decisions to be made faster while maintaining reliability through subsequent detailed verification of borderline cases
Data Source
AI summary
This invention relates to a method of determining stability of unstable equilibrium point (UEP) computed by using BCU method, comprising selecting UEP computed by using BCU method, obtaining a test vector Xtest for the selected UEP, say XUEP using the following equation:Xtest=Xspost+0.99(XUEP−Xspost)where Xspost is the SEP, and checking boundary condition of XUEP by simulating system trajectory of post-fault original system starting from Xtest.