Wireless Phasing Voltmeter Using GPS Reference for Long Range
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Solution Overview
Problem
Existing high voltage phasing voltmeters face challenges in accurately determining phase differences over long distances and in conditions with lower quality data communications, especially when the electrical grid is not operating at its nominal frequency, due to errors in wireless transmission and varying grid stability from intermittent energy sources.
Innovation Solution
A long-range, wireless phasing voltmeter system that uses a Global Positioning Satellite (GPS) clock frequency to generate a precision 60 Hz waveform, allowing for accurate phase angle determination between reference and field conductors, even over simplex communication links, with data transfer as low as two bits per second, and provides audible feedback on grid frequency stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If wireless transmission is used to communicate phase information over long distances, then the measurement range is extended, but transmission errors increase
Solution Approach 1:
The system performs preliminary synchronization by locking onto a common reference frequency (60 Hz) before measuring phase differences. This preliminary action establishes a stable baseline that compensates for transmission errors, allowing accurate measurements over long distances despite wireless transmission challenges
Solution Approach 2:
The system continuously monitors and compares the received reference waveform against the local waveform, using feedback mechanisms to adjust for drift and errors. This closed-loop approach maintains measurement accuracy even when transmission conditions vary over long distances
2Measurement precision
If full-duplex high-speed communication links are used for real-time phase measurement, then measurement accuracy is improved, but device complexity and communication requirements increase
Solution Approach 1:
The system introduces a common reference frequency (60 Hz waveform) as an intermediary that both the reference probe and field probe can independently access. This mediator eliminates the need for complex full-duplex communication, as phase differences can be calculated by comparing local waveforms against this shared reference
Solution Approach 2:
Instead of transmitting actual waveform data, the system transmits only the phase difference information derived from comparing local waveforms with the reference waveform. This copying approach simplifies communication requirements while maintaining measurement precision
3Adaptability or versatility
If phase measurement is performed when grid frequency varies from nominal, then the system adapts to real-world conditions, but measurement accuracy deteriorates
Solution Approach 1:
The system dynamically adjusts to varying grid frequencies by continuously locking onto the actual 60 Hz reference waveform rather than assuming a fixed frequency. This dynamic adaptation allows accurate phase measurements even when the grid frequency deviates from nominal conditions
Solution Approach 2:
The system changes its operating parameters to match the actual grid frequency conditions. By measuring the period of the reference waveform and adjusting the measurement timing accordingly, the system maintains precision across varying frequency conditions
Data Source
AI summary
A wireless phasing voltmeter transmitting two bits per second includes a reference unit using two audio frequency pulses per second to modulate a radio frequency carrier wave for simplex transmission of phase information to a field unit. The time between the two data bits is proportional to the phase difference between the reference voltage waveform and a first GPS-signal based waveform. The audio frequency of the two audio pulses representing the two data bits points to the frequency of the electric grid, rising when the grid frequency is faster and falling when the grid frequency is slower. A meter probe measures the phase angle of the field conductor against a second GPS generated waveform. Comparison yields the phase angle difference between the field conductor and the reference conductor. The radio frequency simplex data transmission perhaps using a cellphone data link, transmitting lower data rates is more reliable over greater distances.