Voltage Source Converter Degraded Mode Control
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Solution Overview
Problem
Voltage source converters in HVDC transmission networks face challenges in maintaining stable operation when switching module performance degrades due to failures or aging, leading to potential power outages and increased maintenance needs.
Innovation Solution
Incorporating a control apparatus that evaluates the performance of chain-link converters and adjusts the coordinated operation by modifying active and reactive power transfer demands, allowing the converter to operate in a degraded mode to maintain power transfer until maintenance can restore full capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage source converter operates with degraded switching module performance, then power transfer can continue temporarily, but the reliability and stability of operation deteriorate
Solution Approach 1:
The control apparatus continuously monitors the performance of switching modules and dynamically adjusts the coordinated operation of chain-link converters based on real-time performance data. This feedback mechanism allows the system to detect degradation early and modify operation to maintain stability while continuing power transfer.
Solution Approach 2:
The system transitions from static operation to dynamic adaptation by modifying the coordinated operation of chain-link converters in response to changing switching module performance. The control apparatus adjusts power transfer demands dynamically, allowing the converter to operate stably across varying conditions of module degradation.
2Reliability
If the control apparatus modifies coordinated operation to maintain power transfer, then availability increases, but the complexity of the control system increases
Solution Approach 1:
The control apparatus performs multiple functions: coordinating chain-link converter operation, evaluating switching module performance, detecting degradation, and modifying power transfer demands. By consolidating these diverse functions into a single multi-functional control system, the patent avoids the need for separate specialized devices for each function.
Solution Approach 2:
The control apparatus autonomously monitors its own operational environment, evaluates performance data, and makes self-directed adjustments to the coordinated operation of chain-link converters without requiring external intervention. This self-service capability reduces the need for additional external control systems.
3Reliability
If the control apparatus continuously evaluates switching module performance, then reliability is improved, but the loss of time for processing and response increases
Solution Approach 1:
The control apparatus evaluates the combined performance of switching modules rather than individually monitoring each module in real-time. This partial evaluation approach focuses on the aggregate performance metric that directly impacts power transfer capability, reducing the computational burden and time required while maintaining adequate reliability monitoring.
Data Source
AI summary
A voltage source converter having first and second DC terminals for connection to a DC network is provided. The voltage source converter includes at least one converter limb that extends between the first and second DC terminals and first and second limb portions that are separated by a respective AC terminal for connection to a corresponding phase of an AC network. Each limb portion includes a chain-link converter which is defined by a plurality of series-connected switching modules which operate in combination to provide a stepped variable voltage source. The voltage source converter includes a control apparatus configured to coordinate operation of the chain-link converters to cause an exchange of power between the DC and AC networks, evaluate the performance of one of the pluralities of series-connected switching modules, and modify the operation of the respective chain-link converter when the performance becomes degraded to a predetermined amount.