LCC Transformer Reuse in VSC Upgrades for UHVDC Converter Stations
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Solution Overview
Problem
The high cost and time-consuming process of replacing Line Commutated Converter (LCC) systems with Voltage-Source Converter (VSC) systems in High-Voltage Direct Current (HVDC) systems, particularly due to the expensive and high-quality LCC transformers, which are costly components in LCC systems.
Innovation Solution
Reusing LCC transformers from existing LCC HVDC systems and integrating them with VSC converter units and bypass breakers to form a VSC system, allowing for efficient AC to DC voltage conversion while enabling operation at full or reduced DC voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LCC systems are replaced with VSC systems to solve multi-infeed problems, then system reliability and adaptability are improved, but the cost and complexity of the system increase significantly
Solution Approach 1:
The patent applies the principle of discarding and recovering by reusing existing LCC transformers in the upgraded VSC system. Instead of discarding the expensive high-quality LCC transformers when replacing LCC systems with VSC systems, the invention recovers and reuses them, significantly reducing the cost and complexity of the upgrade while maintaining system reliability and adaptability benefits
2Adaptability or versatility
If high-quality LCC transformers are replaced with new transformers for VSC systems, then system compatibility is improved, but the economic cost increases significantly
Solution Approach 1:
The patent recovers high-quality LCC transformers from existing LCC systems and reuses them in the VSC system, avoiding the need to purchase new expensive transformers. This significantly reduces the economic cost of the upgrade while maintaining system compatibility through proper configuration of the VSC converter units
Solution Approach 2:
The patent makes the LCC transformers universal by configuring them to work with both LCC and VSC systems. The transformers are adapted to serve multiple functions across different converter types, allowing the same hardware to be reused in the upgraded VSC system without requiring transformer replacement
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 the economic burden of building new VSC systems by utilizing existing LCC transformers, enabling cost-effective operation and flexibility in DC voltage management within the HVDC system.
Implementation Method 1
a plurality of LCC transformers of the LCC HVDC system, the plurality of LCC transformers being operable to transform alternate current (AC) voltage
Implementation Method 2
the plurality of VSC converter units being connected in series and coupled to the plurality of LCC transformers, and being operable to convert between the AC voltage and direct current (DC) voltage
Implementation Method 3
at least one bypass breaker, each of which is connected in parallel with at least one of the plurality of VSC converter units and operable to be closed to bypass the at least one VSC converter unit
Data Source
AI summary
A voltage source converter (VSC) system of a high-voltage direct current (HVDC) system is disclosed. The system includes a number of line-commutated converter (LCC) transformers. Each LCC transformer is operable to transform alternate current (AC) voltage. A number of VSC converter units are connected in series and coupled to the plurality of LCC transformers. Each VSC converter unit is operable to convert between the AC voltage and direct current (DC) voltage. A bypass breaker is connected in parallel with at least one of the VSC converter units and operable to be closed to bypass the at least one VSC converter unit.