Autonomous Local Control for Multi-Terminal DC Power Systems
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Solution Overview
Problem
Conventional multi-terminal DC power systems require central control and fast communication to manage voltage and current dynamics across terminals, leading to increased complexity and sensitivity to communication delays, making it difficult to implement effective control for systems with multiple terminals.
Innovation Solution
The implementation of autonomous local control methods for each terminal, allowing independent operation and occasional low-bandwidth supervisory system coordination, simplifies system design and enhances reliability and fault tolerance by controlling converter-side currents and voltages locally, reducing the need for high-speed communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If central control and fast communication are used to manage voltage and current dynamics, then system control capability is improved, but system complexity and sensitivity to communication delays increase
Solution Approach 1:
The patent divides the centralized control system into distributed autonomous local controllers at each terminal. Each terminal independently controls its own converter-side currents and voltages without requiring centralized coordination, thereby reducing system complexity while maintaining control capability through decentralized decision-making
Solution Approach 2:
Each terminal is equipped with autonomous local control capability that enables it to independently manage its own voltage and current dynamics. The local controllers self-regulate converter-side currents and voltages based on local measurements, eliminating the need for complex centralized control and fast communication infrastructure
2Ease of operation
If central control and fast communication are implemented, then voltage and current dynamics are managed effectively, but reliability and fault tolerance decrease
Solution Approach 1:
The control function is segmented and distributed across multiple independent local controllers rather than being centralized. This segmentation ensures that a failure at one terminal does not propagate to other terminals, thereby improving overall system reliability and fault tolerance while maintaining effective voltage and current dynamics management at each location
Solution Approach 2:
Each terminal's local controller independently manages its own voltage and current dynamics without relying on centralized control signals. This autonomy ensures that communication faults or failures do not compromise system reliability, as each terminal can continue operating with its locally available information and control capabilities
3Device complexity
If autonomous local control methods are used, then system design is simplified and reliability is improved, but coordination between terminals may become challenging
Solution Approach 1:
The autonomous local control method incorporates feedback mechanisms where each terminal monitors its own operating conditions and adjusts its converter-side currents and voltages accordingly. This local feedback enables independent terminals to coordinate their operations implicitly through the physical constraints of the DC network, simplifying system design while maintaining coordination capability
Solution Approach 2:
The DC network itself acts as an intermediary that couples the autonomous terminals. Through the shared DC network, the local control actions at different terminals naturally coordinate to achieve system-wide objectives without requiring direct communication or complex coordination protocols, thus simplifying system design while preserving adaptability
Data Source
AI summary
A multi-terminal DC power system includes: a DC network connecting together multiple terminals. Each terminal is represented by one of: a voltage source converter having a capacitor at an interface to the DC network, wherein a difference between a converter-side current and a network-side current charges the capacitor, and a current source converter having an inductor at an interface to the DC network, wherein a difference between a converter-side voltage and a network-side voltage drives current through the inductor. A local controller for each terminal directly controls the converter-side current of each voltage source controller and the converter-side voltage of each current source converter, independent of the terminals, leaving network-side currents and voltages to be determined by the network, resulting in simplified terminal control and avoidance of the need for high-speed communication among all terminals at all times.