HVDC Breaker Failure Detection via Non-linear Resistor Current
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Solution Overview
Problem
Current breaker failure detection techniques in HVDC systems are inefficient due to reliance on measuring total current decay, which is slow and dependent on external parameters, leading to delayed protective measures and potential overload.
Innovation Solution
A breaker failure detection device and method that monitor the internal commutation process by measuring current commutation from the circuit breaking element to a non-linear resistor, comparing it to desired values, and taking protective measures when deviations occur, allowing for faster and more reliable detection of failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If breaker failure detection is based on measuring total current decay through the DC circuit breaker, then the detection method is simple to implement, but the detection time is prolonged due to slow current decay dictated by the non-linear resistor
Solution Approach 1:
The invention extracts the measurement from the total current through the entire DC circuit breaker and instead measures only the current through the non-linear resistor. This selective extraction of the measurement point isolates the detection from the slow decay characteristics of the overall system, enabling faster detection while maintaining implementation simplicity.
Solution Approach 2:
The non-linear resistor serves as an intermediary element for detection purposes. By measuring the current through this specific component rather than the total circuit current, the detection system obtains a signal that reflects the breaker's operational state more rapidly, without being constrained by the slow decay of the overall system current.
2Reliability
If the current decay time interval is extended to account for various external parameters and safety margins, then the detection becomes more reliable, but the detection time is further prolonged
Solution Approach 1:
The invention removes the dependency on external parameters such as load conditions, fault location, and total inductance by measuring current through the non-linear resistor rather than total circuit current. This extraction of the measurement from system-dependent variables enables reliable detection without requiring extended time intervals for safety margins.
Solution Approach 2:
The invention changes the measurement parameter from total current (which varies with external conditions) to non-linear resistor current (which provides a consistent detection signal). This parameter change eliminates the need to account for varying external parameters and safety margins, achieving both reliability and speed.
3Loss of time
If very large inductances are used to limit the rate of increase of fault induced currents, then the backup breaker has more time to trip, but the system complexity and energy losses increase
Solution Approach 1:
The invention replaces the mechanical approach of using large inductors to limit current rise with an electronic detection system that monitors non-linear resistor current. This substitution eliminates the need for additional passive components while achieving the same protective function through faster detection and control signaling.
Solution Approach 2:
The detection system using non-linear resistor current acts as an intermediary that provides early warning of breaker failure, enabling the backup breaker to trip before fault currents become dangerous. This intermediary detection mechanism eliminates the need for large inductances by providing timely information for protective action.
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
Enables quicker detection of breaker failures, reducing the risk of overload and damage, and allowing for earlier tripping of backup breakers, thus improving the safety and efficiency of HVDC system operations.
Implementation Method 1
The non-linear resistor is connected in parallel with the circuit breaking element
Data Source
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AI summary
A breaker failure detection device for a direct current (DC) circuit breaker (200) is provided. The circuit breaker comprises a circuit breaking element (204) and a non-linear resistor, e.g., a surge arrester (205), connected in parallel. The breaker failure detection device comprises a current sensor (212, 213, 214, 215), for measuring a current commutating from the circuit breaking element (204), and a breaker failure detection unit (211). The breaker failure detection unit (211) is arranged for comparing the measured current to desired values and deciding that an internal commutation process of the circuit breaker (200) does not proceed as desired if the measured current deviates from the desired values. The present invention makes use of an understanding that an improved detection of breaker failures may be achieved by monitoring the internal commutation process of the circuit breaker. Further, a method of breaker failure detection is provided.