Power Feedback Device for Harmonic Reduction in Renewable Energy
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Solution Overview
Problem
Existing power devices for renewable energy sources, such as wind power generation, face issues with serious harmonic pollution, low power factor, and high costs due to the use of large volume converters and electrolytic capacitors, which increase the overall cost and complexity.
Innovation Solution
A power device utilizing a fully controlled power semiconductor device, such as IGBT or IGCT, in conjunction with an isolating transformer with multiple parallel three-phase windings, and a PWM three-phase inverter bridge circuit to improve waveform coefficients, power factors, and harmonic reduction, allowing for efficient power conversion and reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a power converter with the same power as the generator is used in a permanent magnetic generator system, then the power conversion capability is sufficient, but the converter volume and cost increase significantly due to the need for many electrolytic capacitors
Solution Approach 1:
The patent divides the three-phase AC power conversion into multiple independent single-phase conversion paths. Each phase is converted separately through its own rectifier and inverter circuit, allowing the use of smaller capacitors in each path rather than requiring large capacitors for the entire system. This segmentation reduces the overall converter volume while maintaining sufficient power conversion capability.
Solution Approach 2:
The patent uses a multi-path conversion architecture where each conversion path handles a portion of the total power. By distributing the power conversion across multiple parallel paths with smaller individual capacities, the system achieves the required total power conversion capability without needing a single large-capacity converter that would require excessive capacitors and occupy large volume.
2Ease of manufacture
If a semi-controllable power semiconductor device thyristor is adopted, then the cost is low, but serious harmonic pollution occurs at the network side and the power factor is low
Solution Approach 1:
The patent employs fully controllable power semiconductor devices (IGBTs or IGCTs) instead of semi-controllable thyristors. This parameter change in the power semiconductor device enables precise control of the switching timing and duty cycle, allowing for sinusoidal current output and unity power factor operation. The fully controllable devices eliminate the harmonic pollution and low power factor issues inherent in thyristor-based systems, while the modular multi-path architecture keeps the overall system cost manageable.
3Reliability
If a permanent magnetic generator system with a full-power converter is used, then reliability is improved by eliminating slip rings, but the converter cost and volume increase due to the need for many electrolytic capacitors
Solution Approach 1:
The patent segments the power conversion system into multiple parallel single-phase paths, each with its own rectifier and inverter. This segmentation allows the use of smaller capacitors in each path, reducing the total capacitor count and cost while maintaining the reliability benefits of the permanent magnetic generator system without slip rings. The modular architecture achieves cost-effectiveness while preserving high reliability.
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 enhances the power factor and utilization rate of the device, reduces harmonic content, and provides high conversion efficiency, reliability, and ease of maintenance, while being cost-effective and adaptable to different voltage levels.
Implementation Method 1
a PWM three-phase inverter bridge circuit consisting of a filtering capacitor and a fully controlled power semiconductor device
Implementation Method 2
the primary side of the isolating transformer is a three-phase winding and connected with a power network, and the secondary side of the isolating transformer is a multi-path three-phase winding
Data Source
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AI summary
The present invention relates to a power feedback device, including: an AC input power source, which is three-phase or multi-phase AC, or three-phase or multi-phase AC in which the output terminal is connected in series with an inductor, for generating power; a plurality of power converting units, the input terminals of which are respectively connected with two phases of the AC input power source, for power converting the two phases of AC generated by the AC input power source respectively; an isolating transformer, the primary side of which is a three-phase winding and connected with a power network, the secondary side of which is multi-path of three-phase windings and connected with the output terminals of the plurality of power converting units, for feeding the AC converted by the plurality of power converting units back to the power network. The power feedback device according to the present invention can improve the waveform coefficients of the current of the power generation device, and increase the power factors and the utilization rate of the device, and also, the device matches power networks of different voltage levels, thereby improving the waveform coefficients of the current fed back to the power networks and lowering harmonic component.