Variable Speed Drive Circuit Breaker Phase Angle Control
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Solution Overview
Problem
Variable speed drive (VSD) systems face challenges in protecting the drive transformer during connection and disconnection to and from an AC system, leading to potential harm due to improper operation.
Innovation Solution
A VSD arrangement with a control unit that measures electrical properties and determines optimal phase angles for operating the circuit breaker, sending control signals to manage the connection and disconnection, thereby reducing electrical stresses on the drive transformer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the circuit breaker is operated without phase angle control, then the operation is simple and fast, but the drive transformer is harmed due to transient overvoltages and inrush currents
Solution Approach 1:
The control unit determines the optimal phase angle for circuit breaker operation in advance, based on the electrical properties of the connection. By calculating the required phase angle before actuation and sending the control signal at the precise moment, the system prevents transient overvoltages and inrush currents from damaging the drive transformer, while maintaining relatively simple control logic.
2Object-affected harmful factors
If the circuit breaker is operated at arbitrary phase angles, then the operation speed is high, but transient overvoltages and inrush currents harm the drive transformer
Solution Approach 1:
The control unit continuously monitors the electrical properties of the connection between the AC system and the converter, using this feedback information to determine the optimal phase angle for circuit breaker operation. This ensures that the breaker is actuated at the precise moment when transient overvoltages and inrush currents are minimized, protecting the drive transformer while maintaining efficient operation.
3Reliability
If phase angle determination is implemented, then the drive transformer is protected, but the control complexity increases
Solution Approach 1:
The control unit automatically determines the optimal phase angle for circuit breaker operation based on the measured electrical properties of the connection, without requiring external intervention or complex external control systems. This self-service approach protects the drive transformer while keeping the overall system architecture relatively simple, as the existing control unit performs the additional function of phase angle calculation and timing.
Data Source
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AI summary
The invention concerns a variable speed drive arrangement (16) as well as a method and computer program product for operating a circuit breaker (12) from such a variable speed drive arrangement (16). The arrangement (16) is connected between a load (18, 20) and an AC system (10) via a drive transformer (14) and the circuit breaker (12) and comprises an AC to AC converter (24) connected to the AC system (10). It also comprises a control unit (26) controlling the converter (24). When there is a need to operate the circuit breaker (12), the control unit (26) obtains measurements of at least one electrical property (EP) of the connection, determines at least one phase angle when the circuit breaker (12) is to be operated and sends, to the circuit breaker (12), at least one control signal (S) controlling the circuit breaker (12) to perform the operation at the determined phase angle.