Disconnector Voltage Calibration for Non-Synchronous Grid Closing
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Solution Overview
Problem
Existing voltage-balancing circuit breaker control methods in power networks require significant effort and precision, especially when interconnecting non-synchronous networks with different voltage sources, often necessitating dark switching to avoid asynchronous voltage interactions, which can lead to inefficiencies and disruptions.
Innovation Solution
A device and method for automated voltage-balancing circuit breaker control using a high-precision first voltage measuring unit and a less precise second voltage measuring unit, with calibration to ensure voltage amplitude equality and synchronicity, allowing for automated switch control without dark switching, reducing manufacturing and operational effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-precision voltage measuring units are used for all circuit breakers to ensure accurate voltage balancing, then voltage measurement precision is improved, but manufacturing cost and device complexity increase significantly
Solution Approach 1:
The system divides voltage measuring units into two segments: high-precision units for reference voltage measurement and low-precision units for local voltage measurement. This segmentation allows each type to be optimized for its specific function, reducing overall system complexity while maintaining measurement accuracy where critical.
Solution Approach 2:
A calibration unit acts as an intermediary that transfers voltage magnitude information from high-precision reference measurements to low-precision local measurements. This mediator enables low-precision units to achieve accurate voltage balancing capability without requiring high-precision hardware, thus reducing device complexity.
2Productivity
If automated voltage-balancing control is implemented without dark switching, then productivity and ease of operation are improved, but the risk of asynchronous voltage interactions increases
Solution Approach 1:
The control unit continuously monitors voltage magnitude from both sides of the circuit breaker and uses feedback from the calibration unit to adjust switching decisions. This feedback mechanism ensures that automated switching only occurs when voltage balancing conditions are met, preventing asynchronous interactions while maintaining high productivity.
Solution Approach 2:
The system performs preliminary voltage magnitude comparison and calibration before executing the switching operation. By checking voltage balancing conditions in advance and only permitting closure when conditions are satisfied, the system ensures synchronization reliability while enabling automated operation without dark switching.
3Reliability
If voltage balancing control is implemented for all circuit breakers in a substation, then reliability of network interconnection is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The calibration unit serves multiple functions: it calibrates low-precision measuring units, provides reference voltage magnitude information, and enables voltage balancing control across multiple circuit breakers. This multi-functionality allows a single calibration system to support reliability improvements for all circuit breakers without proportionally increasing manufacturing cost.
Solution Approach 2:
Instead of equipping each circuit breaker with independent high-precision voltage measurement capabilities, the system creates a calibrated reference from a single high-precision unit and copies this reference information to multiple low-precision units. This copying approach enables reliable voltage balancing across all breakers at reduced manufacturing cost.
Data Source
Figure 1~2
Figure 3
AI summary
Device and method for voltage-balancing disconnect switch control in a power network (1), wherein the power network has a disconnect switch (2) with a first terminal (2a) that can be supplied with a first voltage (U1) and a second terminal (2b) that can be supplied with a second voltage (U2). The device comprises a first voltage measuring unit (3) configured for repeatedly obtaining a first measuring voltage (U1M) by measuring the first voltage with a predetermined first measuring accuracy (Mg1), a second voltage measuring unit (4) configured for repeatedly obtaining a second measuring voltage (U2M) by measuring the second voltage with a predetermined second measuring accuracy (Mg2) that is lower than the first measuring accuracy, and a calibration unit (5).which is set up to obtain a calibrated second measuring voltage (U2k) by calibrating the second measuring voltage with the first measuring voltage, and a switch control unit (6) which is set up to control the disconnect switch and makes closing the disconnect switch dependent on the fulfillment of one or more predetermined switching conditions (Zb), including that the amplitude difference between the last obtained calibrated second measuring voltage and the last obtained first measuring voltage does not exceed a predetermined maximum amplitude difference.