Phasor Measurement State Estimation Using Complex Power
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Solution Overview
Problem
Existing power network state estimation methods face challenges in accurately tuning voltage phase angle measurements, which affect the robustness and accuracy of state estimator outputs, and fail to utilize complex bus voltage and current measurements effectively, leading to reduced observability and measurement redundancy.
Innovation Solution
The method involves acquiring and synchronizing positive sequence voltage and current phasor measurements, designating a reference phasor measurement, correcting and calculating complex power with real and imaginary components, and using these components as mega-watt and mega-volt-ampere calculations in a state estimation algorithm, thereby increasing measurement redundancy and accuracy without requiring new equation types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If voltage phase angle measurement is added to state estimation, then measurement completeness is improved, but error tuning difficulty increases
Solution Approach 1:
The patent transforms phase angle measurements into complex power measurements by changing the parameter representation from angular to power-based quantities. This parameter transformation allows the use of conventional state estimation techniques without requiring new error tuning procedures, thereby maintaining measurement completeness while avoiding increased complexity.
Solution Approach 2:
Complex power serves as an intermediary that bridges phase angle measurements and conventional state estimation. By using complex power as the intermediate representation, the patent enables the integration of phase angle information without directly introducing new measurement types that would require new error tuning methodologies.
2Adaptability or versatility
If phase angle reference is changed due to frequency changes, then system adaptability is improved, but measurement accuracy deteriorates
Solution Approach 1:
The patent changes the measurement parameter from phase angle to complex power, which is less sensitive to frequency variations and reference changes. Complex power calculations inherently account for frequency changes through the use of synchronized phasor measurements, thereby maintaining measurement accuracy while preserving system adaptability.
Solution Approach 2:
The patent applies synchronization techniques beforehand to cushion against the negative effects of frequency changes and reference shifts. By synchronizing phasor measurements before conversion to complex power, the system pre-compensates for potential accuracy losses, ensuring stable measurements even when frequency or reference conditions change.
3Quantity of substance
If complex bus voltage and current measurements are utilized, then measurement redundancy is improved, but computational complexity increases
Solution Approach 1:
The patent makes complex bus voltage and current measurements serve multiple functions: they are used both for direct state estimation and for calculating complex power measurements. This multi-functionality increases measurement redundancy without proportionally increasing computational complexity, as the same measurements serve dual purposes.
Solution Approach 2:
The patent merges complex voltage and current measurements into a single complex power calculation. By combining these measurements through multiplication (S = V × I*), the patent reduces the number of separate processing streams while maintaining the redundancy benefits of using both voltage and current information.
4Adaptability or versatility
If new equation type is developed for phase angle measurements, then measurement utilization is improved, but system complexity increases
Solution Approach 1:
The patent uses complex power as a copy or representation of phase angle measurements that can be processed by existing state estimation equations. Instead of creating new equation types, the patent copies the information from phase angle measurements into the familiar complex power domain, where conventional equations can be applied without modification.
Solution Approach 2:
Complex power measurements serve as a universal interface that works with both conventional state estimation equations and phase angle information. This universality allows the system to utilize phase angle measurements without developing new equation types, as complex power is already compatible with existing computational frameworks.
Data Source
AI summary
A method of state estimation is provided, including: (a) acquiring a plurality of positive sequence voltage and current phasor measurements; (b) designating a reference positive sequence voltage phasor measurement from the acquired phasor measurements; (c) correcting the acquired phasor measurements to account for the reference phasor measurement; (d) calculating complex power having a real component and an imaginary component, using the corrected positive sequence voltage and current phasor measurement; (e) using the real component of said complex power as a calculated mega-watt and the imaginary component of the complex power as a calculated mega-volt-ampere; and (f) using the mega-watt and mega volt-ampere calculations in a state estimation algorithm.