Dual-Rate Merging Unit for Protection and Fault Waveform Recording
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Solution Overview
Problem
Conventional systems require separate merging units for sampling at 80f and 256f, leading to increased costs and computational burdens in processing and transmitting data for protection control and accident waveform recording in power systems.
Innovation Solution
A merging unit capable of sampling data at different sample rates, including a sample rate conversion processing circuit that converts data from 256f to 80f, allowing a single merging unit to handle both protection control and accident waveform recording functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate merging units are installed for protection control (80f) and accident waveform recording (256f), then data sampling accuracy for different functions is improved, but device complexity and system cost increase
Solution Approach 1:
The merging unit is designed to perform multiple functions by incorporating both an 80f sample rate conversion circuit and a 256f sample rate conversion circuit. This allows a single device to serve both protection control (requiring 80f sampling) and accident waveform recording (requiring 256f sampling) functions, eliminating the need for separate merging units while maintaining sampling accuracy for both applications
2Measurement precision
If a single merging unit samples data at 256f for accident recording, then measurement precision for accident waveform recording is improved, but computation processing burden and memory capacity requirements increase
Solution Approach 1:
The merging unit divides the sampling process into separate pathways: one pathway samples at 80f for protection control functions, and another pathway samples at 256f for accident waveform recording. This segmentation allows each function to receive appropriately optimized data rates, preventing the computation burden of processing 256f data for all protection control applications while maintaining high precision recording capability when needed
3Measurement precision
If data is transmitted at 256f from multiple merging units to one IED for accident recording, then measurement precision is improved, but transmission speed requirements and processing ability requirements increase
Solution Approach 1:
The merging unit dynamically changes the sampling rate parameter based on the destination and function: transmitting at 80f to IEDs for protection control and at 256f to IEDs for accident waveform recording. This parameter adaptation reduces unnecessary high-speed transmission requirements for protection control applications while maintaining high precision transmission capability for accident recording, thereby reducing overall transmission bandwidth requirements
4Adaptability or versatility
If sample rate conversion is performed in IED for protection control, then adaptability to different sample rates is improved, but computation amount and processing burden increase
Solution Approach 1:
The merging unit performs sample rate conversion in advance before data transmission: converting sampled data to 80f when destined for protection control IEDs and maintaining 256f when destined for accident recording IEDs. This preliminary conversion eliminates the need for IEDs to perform complex sample rate conversion computations, reducing their processing burden while maintaining full adaptability to different sample rate requirements
Data Source
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AI summary
A merging unit (4) includes a processing unit which processes an analog signal from a power system and outputs digital data indicating a state of the power system, and a communication unit which communicates with an external device via a communication line. The processing unit includes a first conversion unit which converts an analog signal of current or voltage of the power system to digital data with a first sample rate, and a second conversion unit which converts the analog signal to digital data with a second sample rate lower than the first sample rate. The processing unit is configured to store the digital data with the first sample rate converted by the first conversion unit, over a prescribed period which is based on timing at which the processing unit receives a prescribed signal via the communication unit, and to transmit the digital data with the second sample rate converted by the second conversion unit, via the communication unit.