Series Power Flow Module for Harmonic Current Attenuation
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Solution Overview
Problem
Harmonic currents in power transmission lines, caused by load changes and network switching, are not effectively attenuated by existing technologies, which can disrupt power flow and require innovative solutions for control.
Innovation Solution
A series connected power flow control module using a high-pass filter, phase lock loop, direct-quadrature transform, and inverse transform, coupled with a full bridge inverter and controller, applies sinusoidal PWM voltage injection and calculates injection timing to isolate and attenuate specific high-frequency harmonic components in power transmission lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing technologies are used to attenuate harmonic currents, then the system structure remains simple, but the harmonic current attenuation effectiveness is insufficient
Solution Approach 1:
The system segments the harmonic current problem by using a high-pass filter to separate specific high-frequency harmonic components from the total line current. This segmentation allows the control system to target and attenuate specific harmonic frequencies independently, improving attenuation effectiveness without requiring complete system redesign.
Solution Approach 2:
The patent introduces a current transformer with high permeability core as an intermediary device to accurately detect harmonic current components. This intermediary enables precise measurement and control of harmonic currents, bridging the gap between simple detection and effective attenuation while maintaining reasonable system complexity.
2Reliability
If a series connected power flow control module with multiple control components is used, then harmonic current attenuation effectiveness improves, but the device complexity increases
Solution Approach 1:
The series connected power flow control module performs multiple functions: it acts as a harmonic attenuator, a power flow controller, and a protective device. By integrating these functions into a single module, the system achieves effective harmonic attenuation without proportionally increasing overall system complexity, as the same hardware serves multiple purposes.
Solution Approach 2:
The system implements feedback control by continuously monitoring the line current through the current transformer, comparing it with reference values, and adjusting the series connected module's output accordingly. This feedback mechanism enables automatic harmonic attenuation while maintaining system stability, reducing the need for complex manual control systems.
3Stability of the object's composition
If high-frequency harmonic components are isolated and attenuated using advanced control methods, then power flow stability improves, but the measurement and control difficulty increases
Solution Approach 1:
The patent replaces complex mechanical or analog filtering methods with electronic control systems based on PWM voltage injection. This substitution enables more precise and flexible harmonic attenuation while simplifying the measurement and control process through digital signal processing and standardized electronic components.
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
Effectively isolates and attenuates selected high-frequency harmonic currents, improving power flow stability and reducing harmonic distortions by transforming harmonic currents into slowly varying DC values and using proportional integrators to drive full bridge inverters for impedance injection.
Implementation Method 1
a current transformer having a high permeability core
Data Source
AI summary
A series connectable power flow module is for connection to a power transmission line. The module has a full bridge inverter and a controller. The full bridge inverter has inputs for controlling charging and discharging a DC link capacitor. The controller is coupled to the inputs of the full bridge inverter. The controller is configured to separate a harmonic current from a line current flowing in the power transmission line. The controller operates the full bridge inverter in accordance with the separated harmonic current, to attenuate the harmonic current flowing in the power transmission line through injection of a DC link capacitor voltage.