Injection Unit Bypass Switching for Modular Impedance Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current power grid control systems, reliant on substation-based static synchronous series compensators, are expensive and slow to react to disturbances due to the use of high-speed, high-power switches that generate harmonic oscillations, whereas distributed impedance injection modules face challenges in achieving pseudo-sinusoidal waveform injection efficiently.
Innovation Solution
The implementation of transformer-less flexible alternating current (AC) transmission systems (TL-FACTS) based impedance injection units (IIUs) with built-in intelligence and synchronizable clocks, which communicate via high-speed links to generate and inject impedance in a coordinated manner, forming pseudo-sinusoidal waveforms to reduce harmonic oscillations and enhance grid control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If substation-based static synchronous series compensators use high-speed, high-power switches to generate and inject impedance, then power flow control capability is improved, but harmonic oscillations are generated and system cost increases
Solution Approach 1:
The patent divides the single substation-based SSSC system into multiple distributed impedance injection modules (IIMs) along the transmission line. Each IIM independently generates and injects impedance signals, collectively achieving the power flow control function while distributing the harmonic generation across multiple locations, reducing overall harmonic impact.
Solution Approach 2:
The patent replaces expensive high-speed, high-power switches with simpler, lower-cost switching devices in distributed IIMs. Each IIM uses basic switching components that are cheaper and easier to maintain, collectively achieving the required control capability without the cost and complexity of centralized high-power switches.
2Extent of automation
If substation-based systems are controlled directly by utility, then centralized control is achieved, but reaction speed to disturbances is slow
Solution Approach 1:
The patent segments the centralized control system into distributed intelligent IIMs with local control capabilities. Each IIM can autonomously detect and respond to local disturbances immediately, while still being part of the overall controlled system, achieving both decentralization for speed and coordination for centralized control benefits.
Solution Approach 2:
Each distributed IIM is equipped with built-in intelligence and can autonomously detect disturbances and inject corrective impedance signals without waiting for utility commands. This self-service capability enables immediate local response to disturbances while maintaining system-wide coordination.
3Manufacturing precision
If high voltage switches operate at high-speeds and high power to generate pseudo-sine waves, then sinusoidal waveform for injection is achieved, but heat generation increases and reliability requirements increase
Solution Approach 1:
The patent divides the waveform generation function across multiple distributed IIMs, each contributing a portion of the total impedance injection. This segmentation allows each unit to operate at lower power levels with simpler switching, reducing heat generation per unit while collectively achieving the required sinusoidal waveform quality through coordinated injection.
Solution Approach 2:
The patent uses periodic switching actions in distributed IIMs to generate impedance signals that collectively form sinusoidal waveforms. By coordinating periodic switching across multiple units, the system achieves smooth sinusoidal injection without requiring any single unit to handle high power continuously, reducing heat generation.
Data Source
AI summary
In an impedance injection module in which multiple converter units are placed in series to realize a high level of impedance injection, switches, preferably vacuum interrupters, are connected to short the input and the output terminals of each individual unit. Unlike the fault-protecting switch across the entire module, these switches at the individual converter unit level serve several purposes, overload and surge protection of a unit, insertion loss minimization of an idle unit when the required impedance injection is small, and electrically removing a defective injection unit from the power flow to increase the overall reliability of the impedance injection module in the face of the failure of one unit or a few units. For more rapid response, particularly in response to faults, the vacuum interrupter at the unit level may be accompanied by an SCR switch in parallel with it.