Valve-Based Control for FDCTS DC-Side Oscillation Suppression
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Solution Overview
Problem
Existing methods for suppressing oscillation on the DC side of a Flexible DC Transmission System (FDCTS) require additional hardware and interface changes, leading to increased complexity and cost, while harmonic currents cause significant oscillations that can trigger shutdowns and reduce system reliability.
Innovation Solution
A method using a control algorithm within the Valve-Based Controller (VBC) to calculate and generate corrected bridge arm modulated waves based on standard electrical signals, without requiring additional hardware, by acquiring single-phase active power, DC voltage reference, and bridge arm currents, to suppress oscillations effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional hardware and interface changes are implemented to suppress oscillation, then oscillation suppression effectiveness is improved, but device complexity increases
Solution Approach 1:
The patent replaces physical hardware-based oscillation suppression mechanisms with a control algorithm implemented in the Valve-Based Controller. Instead of adding hardware components like dampers or filters, the solution uses software-based signal processing and control logic to calculate and inject compensation signals that cancel out oscillations, thereby achieving suppression without increasing device complexity
Solution Approach 2:
The system utilizes existing electrical quantity signals already present in the VBC (such as bridge arm currents and modulated waves) to generate the oscillation compensation. The VBC serves itself by using its own internal signals for oscillation suppression, eliminating the need for additional sensors or external hardware interfaces
2Stability of the object's composition
If additional hardware devices are added to suppress oscillation, then system stability is improved, but cost increases
Solution Approach 1:
The Valve-Based Controller is designed to perform multiple functions: it simultaneously executes the primary control functions for the modular multilevel converter and integrates oscillation suppression functionality within the same device. This multi-functionality eliminates the need for separate dedicated oscillation suppression hardware, thereby reducing overall system cost while maintaining stability
3Measurement precision
If additional device interfaces and measurement devices are added, then oscillation detection precision is improved, but device complexity increases
Solution Approach 1:
The patent uses existing electrical quantity signals (such as bridge arm currents and modulated waves) as intermediaries to detect and analyze oscillations. Instead of adding dedicated oscillation sensors, the solution extracts oscillation information from signals that are already being measured and processed by the VBC for other control functions, thereby achieving detection without additional measurement devices
Data Source
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AI summary
Disclosed in the application are a method and apparatus for suppressing oscillation on a direct current (DC) side of a flexible DC transmission system (FDCTS), a computer-readable storage medium, and an electronic device. The method includes the following operations. Single-phase active power on an alternating current (AC) side of a converter valve, a DC voltage reference value of a DC transmission system, a bridge arm current, and a circulating-current control voltage compensation value are acquired. A DC component reference value of a bridge arm current of each phase is calculated according to the single-phase active power on the AC side of the converter valve and the DC voltage reference value of the DC transmission system. A DC component of the bridge arm current of each phase is calculated according to the bridge arm current. A voltage compensation value is calculated according to the DC component reference value of the bridge arm current and the DC component. A corrected bridge arm modulated wave is generated according to the voltage compensation value and the circulating-current control voltage compensation value. According to the application, a problem of oscillation on the DC side may be effectively suppressed, and a stable operation of FDCTS may be achieved, thereby improving reliability of the system. Furthermore, only an electrical quantity signal on a standard interface of an existing Valve-Based Controller (VBC) is used, without requiring additional devices, thereby reducing complexity of the device.