PSR-PWM Inverter Control for Specific Inter-Harmonic Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current research in high-power inverter technology primarily focuses on harmonic control, lacking effective direct control methods for inter-harmonic amplitude and phase modulation, which is essential for improving power quality in power systems.
Innovation Solution
The implementation of a phase-shifted rotating (PSR) pulse width modulation (PWM) technique that allows for precise control of inter-harmonics by shifting and rotating signal frequencies, enabling the generation of specific inter-harmonic signals through phase modulation, suitable for various PWM methods like Sinusoid PWM, Space Vector PWM, and Wavelet PWM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional PWM technology is used for harmonic control, then harmonic compensation can be achieved, but direct control of inter-harmonic amplitude and phase is not available
Solution Approach 1:
The patent applies parameter changes by modifying the phase angle of PWM pulses dynamically. By changing the phase angle parameter of the PWM modulation waveform, the invention achieves direct control over inter-harmonic amplitude and phase, transforming the fixed harmonic control capability into adaptable inter-harmonic control. This resolves the contradiction by enabling precise inter-harmonic control through parameter modification without requiring entirely new control methods.
2Ease of manufacture
If non-selective harmonic compensation is used, then general harmonic reduction is achieved, but specific inter-harmonics cannot be targeted
Solution Approach 1:
The patent applies segmentation by dividing the harmonic control approach into selective components. Instead of treating all harmonics uniformly, the invention segments the control to specifically identify and target particular inter-harmonic frequencies. The PWM phase angle adjustment is segmented to affect specific inter-harmonic components while leaving others unchanged, achieving both simplicity and precision.
3Measurement precision
If selective harmonic compensation is used, then specific harmonics can be targeted, but inter-harmonics remain uncontrolled
Solution Approach 1:
The patent applies universality by creating a control mechanism that serves multiple functions. The PWM phase angle modulation technique universally addresses both traditional harmonic control and the newer inter-harmonic control requirements. This single mechanism can target any frequency component (harmonic or inter-harmonic) by adjusting the phase angle, providing versatile coverage without requiring separate control systems.
4Measurement precision
If PWM phase angle modulation is applied, then inter-harmonic control is achieved, but control algorithm complexity increases
Solution Approach 1:
The patent applies self-service by designing a control algorithm that automatically determines the required PWM phase angle adjustments based on detected inter-harmonic conditions. The system self-regulates by measuring inter-harmonic content and automatically computing the necessary phase angle modifications, eliminating the need for complex external control logic or manual intervention while maintaining high precision control.
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 effectively suppresses sub-harmonics and inter-harmonics in power grids, reducing sub-synchronous and high-frequency oscillations, and allows for precise control of inter-harmonic frequencies within a wide frequency range, enhancing power system stability and quality.
Implementation Method 1
a phase-shifted rotating (PSR) pulse width modulation (PWM) technique to control a specific inter-harmonic in multiple sub-cycles for inverters
Data Source
AI summary
This disclosure provides a PSR-PWM technique for high power active front-end inverters to damp a specific inter-harmonic that may cause relative sub-synchronous resonance in power system. Due to the strong interaction between wind power converters, photovoltaic converters, FACTS devices and HVDC transmission, low-frequency oscillations occur from a few Hz to dozens of Hz, or even high-frequency oscillations ranging from about 300-2000 Hz. Meanwhile, low-frequency oscillations ranging from 0.6 Hz to 7 Hz occur in the power supply systems of many electric locomotives. Even in the case of large-scale train outage, low-frequency oscillation will lead to abnormal locomotive dispatching system; in addition, the power grid voltage disturbance and flicker caused by a large number of high-power are furnaces and other nonlinear loads in the industrial field with a passband inter-harmonic frequency ranging from 0.05 Hz-90 Hz and so on are detected.