Synchronized Phasor Data Acquisition With Time-Shifted Digital Filtering
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Solution Overview
Problem
Existing power system data acquisition systems face challenges in maintaining accurate synchronized phasor measurements due to errors in synchronization and processing delays, which can result in exceeding the total vector error (TVE) maximum, as defined by IEEE Std. C37.118.1-2011, particularly in 60 Hz power systems.
Innovation Solution
The implementation of a power system data acquisition system that includes modules capable of digitizing and filtering signals with introduced time shifts and scaling, using digital filters with adjustable coefficients to align and synchronize signals with external or internal reference clocks, thereby accommodating differences in propagation delays and allowing for full utilization of the digitized signal range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronization errors and processing delays occur in the data acquisition system, then the system can operate with standard components and simpler design, but the total vector error (TVE) exceeds the specified maximum
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing calibration values that compensate for propagation delays and processing times. These calibration values are determined in advance and applied during operation to correct synchronization errors before they affect measurement accuracy, thereby maintaining TVE within specifications without requiring complex real-time correction mechanisms.
Solution Approach 2:
The patent changes parameters by adjusting the timing and phase of sampled signals using calibration values. Specifically, it modifies the time alignment parameters of phasor measurements from different locations to compensate for propagation delays, transforming the system from one with synchronization errors to one that meets TVE specifications through parameter adjustment rather than fundamental redesign.
2Measurement precision
If time shifts are introduced to align signals from different locations, then synchronization accuracy improves, but the device complexity increases due to additional calibration and processing requirements
Solution Approach 1:
The patent applies self-service by implementing automatic calibration procedures that eliminate the need for manual adjustment. The system autonomously determines calibration values based on measured propagation delays and processing times, then automatically applies these corrections to align signals. This self-calibrating approach improves synchronization accuracy while minimizing the complexity burden on operators.
3Measurement precision
If calibration values are used to compensate for propagation delays, then measurement accuracy within the protection window is improved, but the system requires additional memory and processing resources
Solution Approach 1:
The patent applies local quality by implementing calibration values specific to each location and signal path rather than using a single global calibration. Each PMU location has its own set of calibration parameters tailored to its specific propagation delays and processing characteristics. This localized approach maximizes measurement accuracy for each location while optimizing memory usage by storing only the necessary calibration data for each specific path.
Data Source
AI summary
A system comprising an interface configured to condition a signal associated with a power system; a clock module configured to generate a synchronization signal; and a module coupled to the interface and configured to digitize the signal from the interface; filter the digitized signal; and generate a time-shifted, digitized signal in response to the filtering and the synchronization signal.