CCVT High-Fidelity Voltage Measurement via Current Transformer
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Solution Overview
Problem
Conventional voltage transformers in electric power systems lack sufficient fidelity to measure voltage traveling waves accurately, which hinders precise fault location and protection methods, and existing CCVTs produce low-fidelity voltage signals with transient components that can impair impedance protection and increase the risk of CCVT failures.
Innovation Solution
The use of capacitance-coupled voltage transformers (CCVTs) in conjunction with current transformers and advanced signal processing techniques, such as differentiator-smoother filters, to separate incident, reflected, and transmitted traveling waves, and to obtain high-fidelity voltage measurements by analyzing current measurements and parasitic capacitances, thereby improving fault location and protection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage transformers are used, then the device structure is simple, but the measurement precision of voltage traveling waves is insufficient
Solution Approach 1:
The patent segments the voltage measurement function into two parts: a CCVT for voltage transformation and a separate current transformer for measuring the current through the tuning reactor. By measuring the current through the tuning reactor and knowing its impedance, the voltage traveling wave can be calculated, achieving high measurement precision without requiring a complex high-frequency voltage transformer
Solution Approach 2:
The patent introduces an intermediary measurement approach by using the current through the tuning reactor as a mediator to infer the voltage traveling wave. Instead of directly measuring voltage at high frequency, the system measures the intermediate current quantity and derives the voltage, simplifying the overall measurement system while maintaining precision
2Reliability
If CCVT with tuning reactor is used, then voltage transformation is achieved, but transient components are produced that impair impedance protection
Solution Approach 1:
The patent extracts only the useful information (current through the tuning reactor) and ignores the harmful transient components produced by the CCVT. By focusing on measuring the current through the tuning reactor rather than directly using the CCVT output voltage, the system eliminates the impact of transient components on impedance protection
Solution Approach 2:
The patent converts the potential harm of CCVT transients into a benefit by using the tuning reactor current as the measurement basis. The tuning reactor, which is part of the CCVT structure, provides a clean current signal that can be used to derive accurate voltage traveling wave information without being corrupted by the transient issues affecting the direct voltage output
3Measurement precision
If current transformers are added to CCVT, then high-fidelity voltage measurements are achieved, but the device complexity increases
Solution Approach 1:
The patent makes the current transformer serve multiple functions: it measures both the fundamental frequency current for normal operation and the high-frequency current components for traveling wave detection. This multi-functionality allows high-fidelity voltage measurements to be achieved without adding excessive complexity, as the same hardware infrastructure serves multiple measurement needs
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 enables high-fidelity voltage measurements, enhancing the security and speed of impedance protection, improving fault location accuracy, and detecting CCVT failures, thus reducing the risk of hazardous explosions and ensuring reliable operation of electric power systems.
Implementation Method 1
conjunction with current transformers and advanced signal processing techniques, such as differentiator-smoother filters, to separate incident, reflected, and transmitted traveling waves, and to obtain high-fidelity voltage measurements by analyzing current measurements and parasitic capacitances
Implementation Method 2
The use of capacitance-coupled voltage transformers (CCVTs) in conjunction with current transformers
Data Source
AI summary
The present disclosure pertains to systems and methods for detecting traveling waves in electric power delivery systems. In one embodiment, a system comprises a capacitance-coupled voltage transformer (CCVT) in electrical communication with the electric power delivery system, the CCVT comprising a stack of capacitors and an electrical contact to a first ground connection. A current transformer is disposed between the stack of capacitors and the first ground connection. The current transformer provides an electrical signal corresponding to a current associated with the CCVT. An intelligent electronic device (IED) in electrical communication with the first current measurement device generates a voltage signal based on the electrical signal from the current transformer. The IED detects a traveling wave based on the first voltage signal; and analyzes the traveling wave to detect a fault on the electric power delivery system.