HVDC Converter Current Sensor Fault Detection and Replacement
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Solution Overview
Problem
High voltage direct current (HVDC) power transmission and distribution systems face challenges in accurately monitoring and controlling circulating currents within converters, leading to potential operational disruptions due to faulty current sensors, which are not efficiently identified or replaced.
Innovation Solution
Incorporating current sensors in each limb portion of the converter and a current sensor management unit that can detect and replace faulty sensors, ensuring continued operation by calculating replacement current values from other healthy sensors, and implementing a programmable microcontroller to identify and manage faulty sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sensors are installed in each limb portion for accurate current monitoring, then measurement precision is improved, but device complexity increases due to additional sensors and management requirements
Solution Approach 1:
The patent implements a feedback mechanism where the microcontroller continuously monitors current sensor outputs and compares them against expected values. When a sensor malfunction is detected, the system automatically adjusts control signals to compensate, maintaining accurate current monitoring despite sensor failures. This feedback loop resolves the contradiction by enabling high measurement precision while managing the complexity of multiple sensors through automated detection and correction.
Solution Approach 2:
The system performs self-diagnosis and self-correction by automatically detecting faulty sensors and recalibrating other sensors to compensate. The microcontroller monitors sensor outputs and can identify malfunctioning sensors without external intervention, then adjusts the operation of healthy sensors to maintain accurate measurements. This self-service capability reduces the operational complexity of managing multiple sensors while preserving measurement precision.
2Reliability
If multiple current sensors are deployed for redundancy and accurate measurement, then reliability is improved, but loss of information increases due to potential sensor failures and data inconsistency
Solution Approach 1:
The microcontroller implements continuous feedback monitoring of all current sensor outputs, comparing measured values against expected operational ranges. When sensor data becomes inconsistent or erroneous, the system automatically detects the discrepancy and switches to using only reliable sensor data or calculated replacement values, preventing corrupted information from affecting control decisions. This feedback mechanism maintains measurement accuracy while utilizing redundant sensors for reliability.
Solution Approach 2:
The system creates virtual copies of current measurement data through calculation based on healthy sensor readings and known circuit relationships. When a sensor fails, the microcontroller calculates replacement current values using data from other functional sensors and the mathematical relationships inherent in the converter circuitry. This copying approach preserves measurement accuracy by replacing faulty sensor data with calculated equivalents while maintaining the redundancy benefit of having multiple physical sensors.
3Reliability
If a current sensor management unit is implemented to detect and replace faulty sensors, then reliability is improved, but device complexity increases due to additional control circuitry and processing requirements
Solution Approach 1:
The patent merges the functions of current monitoring, sensor fault detection, and replacement calculation into a single microcontroller unit. Rather than adding separate management hardware, the microcontroller integrates multiple functions: it reads sensor outputs, compares values against expected ranges, identifies faulty sensors, and calculates replacement values all within one processing unit. This merging approach improves reliability through comprehensive sensor management while minimizing the increase in device complexity by consolidating control functions.
Solution Approach 2:
The microcontroller is designed as a universal control unit that performs multiple functions: normal converter control, current sensor monitoring, fault detection, and replacement calculation. This multi-functional approach allows a single device to handle both routine operation and anomaly management, improving reliability through comprehensive oversight while avoiding the complexity increase that would result from adding dedicated separate management hardware for each function.
Data Source
Figure 1
Figure 2(a)~2(b)
AI summary
In the field of high voltage direct current (HVDC) power transmission and distribution there is provided a converter (10; 100) which comprises first and second DC terminals (12, 14) for connection to a DC electrical network (16) and between which extends a plurality of converter limbs (18A, 18B, 18C). Each converter limb (18A, 18B, 18C) includes first and second limb portions (20A, 22A, 20B, 22B, 20C, 22C) that are separated by an AC terminal (24A, 24B, 24C) for connection to a respective phase (A, B, C) of a multi-phase AC electrical network (26). Each limb portion (20A, 20B, 20C, 22A, 22B, 22C) includes a current sensor (28) to measure current flowing in the corresponding limb portion(20A, 20B, 20C, 22A, 22B, 22C). The converter (10; 100) also includes a plurality of further current sensors (28), located elsewhere in the converter, and a current sensor management unit (30; 130). The current sensor management unit (30; 130) is programmed to: (a) receive a measured current value (iΤΑ, iΒΑ, iΤΒ, iΒΒ, iTC, iBC, iDCT, iDCB, iphaseA, iphaseB, iphaseC) from each current sensor (28); (b) identify at least one faulty current sensor (28', 28") from the received measured current values (iΤΑ, iΒΑ, iΤΒ, iΒΒ, iTC, iBC,iDCT, iDCB, iphaseA, iphaseB, iphaseC); and (c) replace the measured current value (iphaseA, iphaseB) of the or each identified faulty current sensor (28', 28") with a calculated current value (iP hase A_ Calc, iPhaseB_Calc).