Frequency Control Apparatus for DC Interconnection Systems
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Solution Overview
Problem
Existing frequency control systems for direct current interconnection systems face challenges when multiple systems are interconnected, leading to excessive control and worsened frequency fluctuations due to differing frequency control functions and incorrect calculation of interchange power changes.
Innovation Solution
A frequency control apparatus that includes a frequency deviation detector, a specific frequency deviation extractor, and a control switching unit to switch between power interchange modes, minimizing frequency deviations and preventing excessive control by adjusting the dead band filter's range based on mode switching criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple direct current interconnection systems perform frequency control simultaneously with different control functions, then each system attempts to minimize frequency deviation, but the total interchange power change exceeds the required amount causing excessive control and worsened frequency fluctuations
Solution Approach 1:
The invention segments the frequency control function by designating one system as the master frequency controller and other systems as slave controllers. The master system performs comprehensive frequency control while slave systems follow its control signals, dividing the control authority to prevent excessive total control actions and maintain system stability.
Solution Approach 2:
The invention introduces a control signal transmission mechanism where the master frequency controller acts as an intermediary, sending control signals to slave systems. This mediator coordinate the actions of multiple interconnection systems, ensuring their total interchange power changes match the actual frequency deviation requirements without causing excessive control.
2Reliability
If the interchange power change is adjusted to be smaller to account for multiple direct current interconnection systems, then excessive control is reduced, but when some systems stop operating, the frequency control effect is insufficient
Solution Approach 1:
The invention implements dynamic role assignment where any direct current interconnection system can become the master frequency controller based on operational status. When systems stop or start operating, the master-slave relationship dynamically adjusts, ensuring that the remaining operational systems maintain appropriate control effectiveness without excessive or insufficient control actions.
Solution Approach 2:
The invention incorporates feedback mechanisms where slave frequency controllers monitor the master controller's operation and system frequency deviations. This feedback enables automatic adjustment of control strategies, ensuring that when some systems stop operating, the master controller and remaining slave controllers can maintain appropriate total control effectiveness.
3Adaptability or versatility
If each direct current interconnection system determines interchange power change independently based on frequency deviation, then each system can control frequency, but the sum of their control actions exceeds the required total change causing control conflict
Solution Approach 1:
The invention creates an asymmetric control architecture where one system (master) has full independent frequency control capability while other systems (slaves) have limited control authority that is coordinated through the master. This asymmetric division resolves the control conflict by allowing independent control capability to be maintained by the master system while slave systems contribute to frequency control in a coordinated manner, preventing total control actions from exceeding requirements.
Data Source
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AI summary
A frequency control apparatus is for a plurality of direct current interconnection systems which interconnect two power system (2α, 2β) and control frequencies. The frequency control apparatus includes: a frequency deviation detector (5a) for detecting a frequency deviation of the two power systems (2α, 2β), a specific deviation extractor (6a) for extracting a specific frequency deviation satisfying a predetermined condition from the frequency deviation detected by the frequency deviation detector (5a); and a control switching unit (9a) for switching from frequency control which interchanges power between the two power systems in such a manner as to minimize the specific frequency deviation extracted by the specific frequency deviation extractor (6a) to frequency control which interchanges power between the two power systems (2α, 2β) in such a manner as to minimize the frequency deviation detected by the frequency deviation detector.