FACTS Device Bypass Using H-Bridge Topology
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Solution Overview
Problem
Existing Flexible AC Transmission Systems (FACTS) devices with series-connected protection schemes face issues of increased complexity, weight, and cost due to the need for a single bypass-breaker to protect multiple devices, which can lead to unnecessary bypassing of all devices when one needs to be isolated.
Innovation Solution
A FACTS device with an H-bridge topology incorporating four switches, a capacitor, and a state machine that operates in multiple modes, including a local bypass monitoring mode and low-loss monitoring mode, allowing for selective bypassing and diagnostic capabilities to manage fault currents efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single bypass-breaker is used to protect multiple series-connected FACTS devices, then the number of protection devices is reduced, but the complexity and cost of the system increases
Solution Approach 1:
The bypass-breaker is segmented into multiple independent breaker elements (first breaker element, second breaker element, etc.), each corresponding to a specific FACTS device. This allows selective bypass of individual devices while maintaining protection for the entire series-connected system, resolving the contradiction between reduced device count and selective bypass capability.
Solution Approach 2:
The single bypass-breaker is designed with multi-functionality to serve multiple FACTS devices simultaneously. Each breaker element can independently operate to bypass its corresponding device, providing both centralized protection and selective isolation capabilities in one unified structure.
2Reliability
If each series-connected FACTS device is protected by an individual bypass-breaker, then selective bypass capability is improved, but the weight and cost of the system increases
Solution Approach 1:
Multiple breaker elements that would traditionally be separate individual bypass-breakers are merged into a single integrated bypass-breaker structure. This consolidation maintains the selective bypass capability of individual devices while reducing the overall weight and footprint compared to having completely separate protection devices for each FACTS device.
3Device complexity
If a single bypass-breaker protects multiple FACTS devices, then the number of components is reduced, but the cost of the system increases
Solution Approach 1:
The bypass-breaker is divided into modular breaker elements that can be manufactured and assembled in a standardized manner. This segmentation allows for economies of scale in manufacturing while maintaining the ability to selectively bypass individual devices, reducing overall system cost compared to fully customized individual protection devices.
Solution Approach 2:
The single bypass-breaker is designed as a universal protection device that can serve multiple FACTS devices through its multiple breaker elements. This multi-functionality reduces the total number of components needed in the system, lowering manufacturing costs while maintaining selective bypass capability.
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
The solution reduces system complexity and cost while enabling precise control over bypass operations, ensuring that only the affected device is bypassed during faults, maintaining efficiency and safety in high-voltage power transmission lines.
Implementation Method 1
A non-monitoring mode charges and discharges the capacitor, to inject a voltage into a high-voltage (HV) power transmission line, to modify power grid characteristics
Implementation Method 2
The middle of the H-bridge is connectable across a series connection of the current transformer and an alternating current (AC) current source
Data Source
AI summary
A system and method using four switches connected in an H-bridge (full bridge) topology within a series-connected FACTS device is disclosed. System and method can be used to bypass a FACTS device. The switches in H-bridge are connected to an alternating current (AC) source allowing for various switching states, and enabling non-monitoring mode, local bypass monitoring mode, low-loss monitoring mode, and diagnostic mode of operation.