Multiphase AC Voltage Estimation for Stable Power Control
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Solution Overview
Problem
Existing methods for determining radius and phase angle values of time-domain symmetrical sequence components in AC voltage networks face instability and computational delays, particularly in multi-phase AC networks, which affect power system stability and quality.
Innovation Solution
A method that expresses measured AC voltage as a summation of polar quantities and iteratively calculates actual radius and phase angle values using an estimator module, such as a proportional integral controller, to drive differences to zero, avoiding the need for synchronous rotating frame transformations and discrete sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronous rotating frame transformations are used to determine radius and phase angle values, then measurement precision can be achieved, but computational delay and processing overhead increase significantly
Solution Approach 1:
The patent extracts only the essential information (radius and phase angle values) directly from the measured signal in the time domain, eliminating the need for complex synchronous rotating frame transformations. This is achieved by using an estimator module that directly computes the required parameters from the measured AC voltage, thereby reducing computational delay while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical/computational process of synchronous rotating frame transformations with a more efficient estimation algorithm. The estimator module uses a simplified mathematical approach that directly yields radius and phase angle values without requiring coordinate transformations, thus substituting a complex computational mechanism with a more efficient one.
2Reliability
If existing estimation methods are used to determine symmetrical sequence components, then power system stability can be maintained, but instabilities and computational complexity arise
Solution Approach 1:
The patent changes the approach from transforming signals into synchronous rotating frames to directly estimating parameters (radius and phase angle) in the time domain. This parameter change simplifies the computational process while maintaining the reliability needed for power system stability, as the estimator module directly computes the essential characteristics without complex intermediate transformations.
Solution Approach 2:
The patent segments the problem into directly estimating radius and phase angle values separately using an estimator module, rather than performing comprehensive synchronous rotating frame transformations. This segmentation allows for more efficient computation while maintaining the necessary accuracy for power system stability control.
3Measurement precision
If discrete sampling periods are used in the estimation process, then measurement can be performed, but the calculation speed is slowed down
Solution Approach 1:
The patent implements continuous estimation of radius and phase angle values using the estimator module, rather than relying on discrete sampling periods. This continuous action allows for real-time computation of actual measured values without the delays inherent in discrete sampling, thereby maintaining measurement precision while significantly improving calculation speed and productivity.
Data Source
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AI summary
In the field of multi-phase AC networks there is a need for improved AC network voltage and power control, and overall power system stability. A method of determining actual first and second radius and phase angle values (rp, θρ, rn, θn) of a first time-domain symmetrical component vabc+ of an AC voltage in a multi-phase AC network (10) comprises the steps of: (a) expressing a measured AC voltage (vabc) in the AC network (10) as at least a first time-domain symmetrical sequence component vabc+; (b) equating the first time-domain symmetrical sequence component vabc+ to a summation of first and second polar quantities, the first polar quantity having a first radius value (rp) and a first phase angle value (θp) and the second polar quantity having a second radius value (rn) and a second phase angle value (θn); and (c) calculating actual first radius and phase angle values (rp, θρ) by iteratively subtracting estimated second radius and phase angle values (r̂n, θ̂n) from the first time-domain symmetrical sequence component vabc+ and calculating actual second radius and phase angle values (rn, θn) by iteratively subtracting estimate first radius and phase angle values (r̂p, θ̂p) from the first time-domain symmetrical sequence component vabc+, both while driving the difference between the estimated (r̂p, θ̂p, r̂n, θ̂n) and actual (rp, θp, rn, θn) values to zero.