Adjustable Length Filter for Variable Frequency Power System Measurements
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Solution Overview
Problem
Intelligent electronic devices (IEDs) in electric power delivery systems face challenges in maintaining accurate measurements and efficient communication due to variable power system frequencies, which result in increased latency and communication delays when trying to synchronize data acquisition and signal processing rates across multiple devices.
Innovation Solution
Implementing a system with a constant data acquisition and signal processing rate synchronized to a globally available time source, such as a Global Navigation Satellite System (GNSS), allowing for frequency tracking while performing measurements over an integer number of power system cycles, and using an adjustable length filter to attenuate double frequency components, enabling synchronized and efficient data exchange among IEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If IEDs adjust data acquisition and signal processing rates to follow power system frequency variations, then measurement accuracy is improved, but communication latency and synchronization delays increase among multiple devices
Solution Approach 1:
The system dynamically adjusts the measurement window length based on the detected power system frequency. When frequency deviates from nominal, the measurement window is adjusted to maintain an integer number of cycles, enabling accurate measurements while operating at a constant fixed processing rate that ensures synchronized communication across all IEDs
Solution Approach 2:
The invention changes the measurement window parameter (number of samples) based on the detected frequency condition. By calculating the appropriate window length to correspond to an integer number of power system cycles at the current frequency, the system maintains measurement accuracy without requiring variable processing rates, thus avoiding communication latency issues
2Measurement precision
If IEDs operate at variable processing rates to track power system frequency, then frequency tracking accuracy is improved, but data exchange synchronization and communication efficiency deteriorate
Solution Approach 1:
The system dynamically adapts the measurement window length to track frequency variations while maintaining a constant fixed processing rate. This allows the IED to accurately follow power system frequency changes without compromising data exchange synchronization, as all devices operate at the same fixed rate
Solution Approach 2:
The invention provides a universal solution that works for both frequency tracking and synchronized communication. By using a fixed processing rate with adaptive measurement windows, the system simultaneously achieves accurate frequency measurement and maintains efficient synchronized data exchange across all IEDs in the network
3Stability of the object's composition
If IEDs use fixed processing rates for data acquisition, then communication synchronization is improved, but measurement accuracy over integer power system cycles deteriorates when frequency varies
Solution Approach 1:
The system dynamically adjusts the measurement window length based on the detected power system frequency while maintaining a fixed processing rate. This ensures that measurements are always taken over an integer number of power system cycles, preserving measurement accuracy without compromising synchronization stability
Solution Approach 2:
The invention changes the measurement window parameter to adapt to frequency variations. By calculating the appropriate number of samples corresponding to an integer number of cycles at the current frequency, the system maintains both fixed-rate synchronization and cycle-accurate measurements
Data Source
AI summary
A method includes obtaining electrical measurements of an input signal of a power system. The electrical measurements are obtained at a sampling frequency and the input signal is indicative of an operating frequency of the power system. The method includes generating an intermediate signal from the input signal. The intermediate signal has a direct current (DC) component indicative of a magnitude and a phase of the input signal. The method includes filtering the intermediate signal using an adjustable length filter to obtain the magnitude and the phase of the input signal. The length of the adjustable length filter varies based at least in part on a period measurement of the power system.