Bipolar DC Transmission Converter Blocking for Mutual Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In bipolar DC power transmission schemes, mutual coupling between faulty and healthy DC poles can lead to overcurrent and overvoltage in converters connected to the healthy pole, interfering with power transmission and increasing the risk of damage, despite the healthy pole being expected to continue operating unaffected.
Innovation Solution
Incorporating a controller and monitoring device that temporarily block converters connected to the healthy DC pole based on fault identification, using a current return path to monitor the direction of current and manage converter blocking and deblocking to maintain safe operating limits and minimize power interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If converters connected to the healthy DC pole continue operating without blocking, then power transmission continuity is maintained, but overcurrent and overvoltage occur due to mutual coupling with the faulty pole
Solution Approach 1:
The controller temporarily blocks converters connected to the healthy DC pole in advance before fault clearance is complete. This preliminary blocking action prevents the mutual coupling effects from causing overcurrent and overvoltage, while the system quickly identifies and clears the fault to restore operation, thus maintaining overall power transmission continuity
Solution Approach 2:
The controller acts as an intermediary between the faulty and healthy DC poles by selectively blocking converters on the healthy pole. This intermediate control measure isolates the harmful mutual coupling effects while allowing the system to clear the fault and resume normal operation, balancing protection with continuity
2Reliability
If converters connected to the healthy DC pole are blocked to prevent damage, then converter safety is improved, but power transmission interruption increases
Solution Approach 1:
Converters on the healthy pole are blocked temporarily as a preliminary protective measure during fault clearance. The system quickly identifies the faulty pole using the monitoring device and clears the fault, then rapidly restores converter operation, minimizing the duration of blocking while ensuring converter safety
Solution Approach 2:
The monitoring device continuously monitors current direction in the return path and provides feedback to the controller. This feedback mechanism enables the controller to make real-time decisions about blocking and deblocking converters, ensuring they remain blocked only as long as necessary for safety while minimizing unnecessary interruption time
3Object-affected harmful factors
If all converters are blocked in response to fault on one DC pole, then converter damage risk is reduced, but power transmission efficiency decreases
Solution Approach 1:
Instead of uniformly blocking all converters, the controller selectively blocks only those converters connected to the healthy DC pole that are affected by mutual coupling. This localized blocking approach protects vulnerable converters while allowing other parts of the system to continue operating, thus maintaining power transmission efficiency
Solution Approach 2:
The bipolar DC power transmission system is segmented into faulty and healthy poles, with further segmentation of converters on the healthy pole into those affected by mutual coupling and those that are not. This segmentation enables selective blocking of only the necessary converters, protecting against damage while minimizing impact on overall transmission efficiency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces adverse effects from mutual coupling, allowing converters on the healthy pole to operate within safe limits while minimizing power transmission interruptions, enabling continuous power transmission.
Implementation Method 1
the monitoring device is configured to identify the faulty one of the first and second DC poles on which the fault has occurred by monitoring the direction of current in the current return path
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A bipolar DC power transmission scheme (30) comprises: first and second DC poles, each DC pole including a respective DC power transmission medium (40,42) extending between two ends; a plurality of first converters (32) and a plurality of second converters (34), wherein each end of the DC power transmission medium (40) of the first DC pole is respectively operatively connected to at least one of the plurality of first converters (32), and each end of the DC power transmission medium (42) of the second DC pole is respectively operatively connected to at least one of the plurality of second converters (34); a controller (36) programmed to block one or more of the plurality of first and second converters (32,34) in response to a fault (64) occurring on either of the first and second DC poles; and a monitoring device (38) configured to identify the faulty one of the first and second DC poles on which the fault (64) has occurred, wherein the controller (36) is further programmed to deblock the or each blocked converter (32,34) connected to the healthy other of the first and second DC poles after the monitoring device (38) has identified the faulty one of the first and second DC poles on which the fault (64) has occurred.