Bidirectional Converter for Series AC Source Balancing
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Solution Overview
Problem
Conventional power generation networks face challenges in achieving cost-effective high voltage transmission from ac sources like wind, wave, and tidal turbine-generators or PV arrays, requiring proper isolation, power control, and fault management, especially when sources generate unequal power.
Innovation Solution
The solution involves a power generation network with a series dc bus and a parallel balancing bus interfaced through bidirectional power converters, where ac power from multiple sources is rectified and connected in series to achieve high voltage dc transmission, with a controller managing power distribution and balancing to ensure maximum power extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If ac sources are connected in series to achieve high voltage transmission, then transmission efficiency is improved, but control complexity increases due to unequal power generation from different sources
Solution Approach 1:
The system divides the power conversion function into separate modular units, with each ac source connected to its own converter system. This segmentation allows independent control of each source while maintaining series connection for high voltage transmission, resolving the contradiction between transmission efficiency and control complexity.
Solution Approach 2:
A parallel balancing bus is introduced as an intermediary component that receives power from all ac sources and redistributes it to maintain power balance. This mediator enables simple individual source control while achieving overall system coordination, reducing control complexity despite series connection requirements.
2Adaptability or versatility
If bidirectional converters are used for power balancing, then power distribution flexibility is improved, but device complexity increases
Solution Approach 1:
The bidirectional converter is designed to perform multiple functions: rectification of ac power, power balancing through the parallel bus, and injection into the series dc bus. This multi-functionality consolidates several operations into a single device, achieving power distribution flexibility without proportionally increasing overall system complexity.
Solution Approach 2:
The converter operates in different modes dynamically - rectifying mode for normal operation and balancing mode when power redistribution is needed. This dynamic operation allows the system to adapt to varying power generation conditions while using a standardized converter design, balancing flexibility and complexity.
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 enables efficient long-distance transmission of power from diverse ac sources by maintaining a stable high voltage dc output, balancing variations in power generation, and optimizing power factor, thereby enhancing the overall efficiency and reliability of the power transmission system.
Implementation Method 1
The rectifier has a first set of terminals inductively coupled to an ac power source and a second set of terminals coupled in series with a series dc bus. The rectifier is operable to convert ac power at the first set of terminals to dc power at the second set of terminals.
Data Source
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AI summary
A converter system (108) for coupling to an ac power source (106) includes a rectifier (404) and a bi-directional converter (406). The rectifier (404) has a first set of terminals (408) inductively coupled to an ac power source (106) and a second set of terminals (412) coupled in series with a series dc bus (102), and is operable to convert ac power at the first set of terminals (408) to dc power at the second set of terminals (412). The bi-directional converter (406) has a first set of terminals (414) coupled to the ac power source (106) and a second set of terminals (418) coupled to a parallel bus (104), and is operable to transfer power from the ac source (106) to the parallel bus (104) in a first operating mode and transfer power from the parallel bus (104) to the series dc bus (102) via the rectifier (404) in a second operating mode. A corresponding power generation network (100) and power transmission method are also provided.