HVDC Link Control Module for Asymmetrical Fault Response
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Solution Overview
Problem
Existing HVDC transmission systems face challenges in quickly responding to asymmetrical faults without relying on communication signals, leading to inefficiencies and increased costs due to the need for DC choppers or delayed reaction times.
Innovation Solution
A control module that directly monitors HVDC transmission link parameters to detect unbalanced faults and regulates the AC power plant output by providing unbalanced multi-phase signals, allowing for immediate and reliable fault response without communication, thereby maintaining power balance and reducing the need for DC choppers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DC chopper is used to dissipate excess active power during asymmetrical faults, then the power plant can stay connected to the grid, but the system cost increases and energy efficiency decreases
Solution Approach 1:
The invention converts the harmful excess active power that needs to be dissipated into a useful function by using it to create an unbalanced voltage condition at the collector network. This unbalanced voltage actively controls the wind turbines to reduce their active power output, thereby eliminating the need for energy-dissipating DC choppers while maintaining fault-ride-through capability
2Reliability
If communication signals are used to convey fault information to the power plant, then the power plant can adjust its output, but the response time increases
Solution Approach 1:
The system uses the inherent physical parameter (HVDC transmission link voltage) to automatically detect and respond to asymmetrical faults without requiring external communication signals. The voltage change itself serves as the detection mechanism, enabling immediate local response and eliminating communication delays
3Productivity
If the power plant continues to generate active power during asymmetrical faults, then the power generation remains stable, but excess DC voltage occurs that must be managed
Solution Approach 1:
The invention dynamically adjusts the power plant's active power output in real-time during asymmetrical faults by creating an unbalanced voltage condition. This dynamic control allows the system to respond flexibly to varying fault conditions and power imbalances, eliminating the need for static excess power management equipment like DC choppers
Data Source
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AI summary
The invention describes a method of controlling the power input to a HVDC transmission link (2), which HVDC transmission link (2) is connected to an AC power plant (1) by means of a first voltage source converter (10) and to an AC grid (3) by means of a second voltage source converter (30), which method comprises using the second voltage source converter (30) to perform voltage control of the HVDC transmission link (2) during a no-fault mode of operation of the grid (3); monitoring a HVDC transmission link parameter (UWPP' UGRID) to detect an unbalanced fault; and using the first voltage source converter (10) to regulate the output of the AC power plant (1) on the basis of the monitored HVDC transmission link parameter (UWPP' UGRID) in the event of an unbalanced fault. The invention also describes a control module (100) for controlling the power input to a HVDC transmission link (2); a voltage source converter (10) for a power plant (1); and a power generation and transmission arrangement (5).