CCVT Voltage Measurement via Tuning Reactor Current
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Solution Overview
Problem
Conventional voltage transformers in electric power systems lack sufficient fidelity to accurately measure voltage traveling waves, which hinders precise fault location and protection methods, and existing CCVTs produce transients that interfere with impedance protection, leading to potential security and speed issues during short-circuits.
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 provide high-fidelity voltage measurements, reducing CCVT-induced transients and improving fault location and protection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage transformers are used, then the device complexity is low, 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 using it to calculate the voltage traveling wave, the system achieves high measurement precision without requiring a complex high-fidelity voltage transformer
Solution Approach 2:
The patent uses the tuning reactor as an intermediary element. The current transformer measures the current through the tuning reactor, which is then used to derive the voltage traveling wave information. This intermediary approach allows accurate voltage measurement without directly measuring the voltage with a complex transformer
2Measurement precision
If CCVTs are used to improve voltage measurement fidelity, then the measurement precision improves, but harmful transients are generated that interfere with impedance protection
Solution Approach 1:
The patent extracts only the necessary information (current through the tuning reactor) using a simple current transformer, rather than relying on the full CCVT output which contains harmful transients. By taking out only the useful signal component and deriving the voltage traveling wave from it, the system achieves high-fidelity measurement without the harmful CCVT transients
Solution Approach 2:
The patent converts the tuning reactor, which normally serves a different function, into a useful sensor element. The current through the tuning reactor provides the necessary information for voltage traveling wave measurement, turning a potential source of complexity into a beneficial measurement point that avoids CCVT transient issues
3Reliability
If high-fidelity voltage measurements are implemented, then the reliability of fault location improves, but the device complexity increases
Solution Approach 1:
The patent replaces the mechanical/electrical system of high-fidelity voltage transformation with a signal processing approach. By measuring current and using differentiation and smoothing operations, the system achieves reliable fault location without the complexity of specialized high-fidelity voltage transformers
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 more accurate and reliable fault location, improved protection security, and faster response times by providing high-fidelity voltage signals that are free from CCVT transients, enhancing the performance of impedance protection systems and reducing the risk of CCVT failures.
Implementation Method 1
capacitance-coupled voltage transformer (CCVT)
Implementation Method 2
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. Electrical signals from accessible portions of the CCVT are used to detect traveling waves. Current and/or voltage signals may be used. In various embodiments, a single current may be used. The traveling waves may be used to detect a fault on the electric power delivery system.