HVDC Breaker Segments Current and Voltage Paths
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Solution Overview
Problem
High voltage DC breakers face significant steady-state losses due to continuous current stress on power semiconductor switches, leading to high costs and maintenance issues, while existing solutions with mechanical switches suffer from arc-related wear and complex voltage distribution challenges.
Innovation Solution
A device comprising a parallel connection of a main breaker with a non-linear resistor and a series connection of a high-speed mechanical switch and an auxiliary breaker, where the auxiliary breaker has a lower on-resistance, allowing current commutation to the main breaker and reducing steady-state losses, and eliminating the need for parallel capacitors for voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If solid state DC breakers are used with multiple series connected power semiconductor switches, then the breaker can operate at high voltage levels, but the steady-state losses increase significantly
Solution Approach 1:
The breaker is divided into two independent parallel branches: a first breaker containing power semiconductor switches for voltage blocking, and a second breaker containing a mechanical switch for current conduction. This segmentation allows each component to perform its specialized function, reducing overall losses while maintaining high voltage capability.
Solution Approach 2:
The mechanical switch acts as an intermediary that takes over current conduction during normal operation, allowing the power semiconductor switches to be current-free and loss-free. The mechanical switch mediates between the need for high voltage blocking and the need to minimize steady-state losses.
2Loss of energy
If a mechanical switch is used to reduce steady-state losses, then losses are reduced, but arc-related wear occurs at the breaking points
Solution Approach 1:
The invention uses a parallel structure where the mechanical switch copies the current conduction function during normal operation, but the actual current interruption is performed by the first breaker with power semiconductor switches. This allows the mechanical switch to avoid arc-related wear while still reducing steady-state losses.
3Stress or pressure
If multiple mechanical switches are connected in series for high voltage applications, then voltage distribution becomes uneven, but parallel capacitors are required to ensure even voltage distribution
Solution Approach 1:
The invention extracts the voltage blocking function from the mechanical switch and assigns it to the first breaker with power semiconductor switches. The mechanical switch in the second breaker only handles current conduction during normal operation and is opened before current interruption, eliminating the need for parallel capacitors and complex voltage distribution mechanisms.
4Ease of operation
If the mechanical switch actively breaks the current to commutate to the solid state breaker, then current commutation is achieved, but arcs occur leading to early wear
Solution Approach 1:
The mechanical switch is opened in advance before current interruption to commutate current to the first breaker. This preliminary action allows the power semiconductor switches to assume the current, and then the first breaker opens without arc-related wear since it uses solid state switching for current interruption.
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
The solution reduces steady-state losses, minimizes thermal overload, and extends the lifespan of power semiconductor switches by reducing wear and maintenance needs, while enabling simpler design and reliable operation with reduced equipment costs.
Implementation Method 1
a parallel connection of a main breaker (8) and a non-linear resistor (11)
Implementation Method 2
the main breaker (8) comprising at least one power semiconductor switch
Implementation Method 3
a series connection of a high speed switch (10) and an auxiliary breaker (9)
Data Source
Figure 1~4
Figure 5~6
Figure 7
AI summary
A device (13) to break an electrical current flowing through a power transmission or distribution line (14) comprises a parallel connection of a main breaker (8) and a non-linear resistor (11), where the main breaker (8) comprises at least one power semiconductor switch of a first current direction. The device (13) further comprises a series connection of a high speed switch (10) comprising at least one mechanical switch and of an auxiliary breaker (9), the auxiliary breaker having a smaller on-resistance than the main breaker (8) and comprising at least one power semiconductor switch of the first current direction. The series connection is connected in parallel to the parallel connection. In a method to use the device (13) first the auxiliary breaker (9) is opened, thereby commutating the current to the main breaker (8), afterwards the high speed switch (10) is opened and afterwards the main breaker (8) is opened thereby commutating the current to the non-linear resistor (11). The device (13) can further be used in a current limiting arrangement.