Coherent ADC Sampling for Power Signal Phase Tracking
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Solution Overview
Problem
Incoherent sampling in power distribution systems leads to ripples in measured phasor frequency and magnitude due to frequency deviations from the nominal frequency, making existing methods inaccurate for tracking phase properties.
Innovation Solution
Implementing a coherent sampling technique using a phase-locked loop (PLL) to adjust the sampling rate of an analog-to-digital converter (ADC) based on the phase and frequency of the power signal, ensuring that sampling occurs at integral multiples of the signal cycle, thereby generating accurate synchrophasors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If incoherent sampling with fixed ADC sampling rate is used, then device complexity is reduced, but measurement precision deteriorates due to ripples in measured phasor frequency and magnitude
Solution Approach 1:
The patent implements dynamic sampling rate adjustment by using a phase-locked loop (PLL) to continuously track the power signal frequency and adjust the ADC sampling rate accordingly. This transforms the fixed sampling system into a dynamic one that adapts to frequency variations, resolving the contradiction between simple fixed-rate sampling and accurate variable-frequency measurement.
Solution Approach 2:
The patent changes the sampling rate parameter from a fixed value to a variable that tracks the power signal frequency. By making the sampling rate a dynamic parameter rather than a constant, the system maintains measurement accuracy across different operating conditions without requiring complex additional hardware.
2Ease of operation
If incoherent sampling is used, then ease of operation is improved, but reliability deteriorates due to inaccurate phase tracking when frequency deviates from nominal
Solution Approach 1:
The patent introduces feedback through a phase-locked loop (PLL) that continuously monitors the power signal phase and frequency, then feeds this information back to adjust the sampling rate. This feedback mechanism ensures reliable phase tracking while maintaining operational simplicity, as the adjustment occurs automatically without manual intervention.
Solution Approach 2:
The system performs self-adjustment of the sampling rate based on the power signal characteristics. The PLL automatically detects frequency deviations and adjusts the sampling parameters without external control, making the system self-sufficient in maintaining accuracy while keeping operation simple.
3Measurement precision
If coherent sampling with PLL is implemented, then measurement precision is improved, but device complexity increases due to additional tracking circuitry
Solution Approach 1:
The patent makes the ADC and control system multi-functional by using the same hardware components for both normal signal conversion and frequency tracking. The PLL and sampling rate controller serve dual purposes: maintaining synchronization for accurate measurement and adapting to frequency variations, thereby reducing the need for separate dedicated tracking hardware.
Solution Approach 2:
The patent merges the frequency tracking function with the existing ADC sampling system by integrating the PLL directly into the sampling rate control. This combination eliminates the need for separate tracking circuits and allows the same hardware to perform both measurement and adaptation functions, reducing overall system complexity despite the enhanced capabilities.
4Reliability
If coherent sampling is used, then reliability is improved, but loss of time increases due to the adjustment process
Solution Approach 1:
The patent ensures continuous frequency tracking and sampling rate adjustment through the PLL, which operates continuously rather than in discrete steps. This continuous operation eliminates gaps in measurement and reduces the effective time loss by maintaining uninterrupted synchronization with the power signal throughout the process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides stable and accurate measurements of phase, frequency, and magnitude, reducing fluctuations and enabling faster response times without the need for filtering, thus improving the precision of power signal tracking.
Implementation Method 1
a phase-locked loop (PLL) to adjust a sampling rate of the ADC based on the phase and frequency of the power signal
Data Source
AI summary
Embodiments of the present disclosure may monitor and adjust a sampling rate of an ADC for converting the power signal to a digital signal, locking onto the phase and frequency of the power signal. This technique may make the sampling process coherent relative to the power signal. Properties of the power signal, such as phase, frequency, and magnitude, may be extracted relative to an idealized power signal.