Multistage Power Conversion With DC Buffer for Grid Voltage Stability
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Solution Overview
Problem
The interconnection of AC power electronic converters to the grid faces challenges due to unstable voltage stability and harmonic content, leading to excess voltage fluctuations and increased energy consumption and thermal losses in consumer loads.
Innovation Solution
A multi-stage, back-to-back power conversion system with independently controlled DC-AC inverters, utilizing ultrahigh efficiency converters and advanced control algorithms, including neural networks, to optimize voltage and frequency based on DC element charge levels, reducing impedance and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard grid connection is used, then interconnection to AC grid is achieved, but voltage stability and harmonic content deteriorate
Solution Approach 1:
The patent introduces a multistage power conversion system with DC elements as an intermediary between the AC grid and consumer loads. This intermediary system converts unstable grid voltage into stable DC voltage, which is then converted to controlled AC voltage for loads, effectively isolating loads from grid voltage fluctuations and harmonic content.
Solution Approach 2:
The system dynamically changes voltage and frequency parameters through controlled power conversion stages. The first power conversion stage converts grid voltage to DC voltage, and the second stage converts DC voltage to controlled AC voltage with optimized parameters, allowing the system to adapt to varying grid conditions and maintain stable output.
2Power
If excess voltage is delivered to loads, then power delivery is increased, but energy consumption and thermal losses increase
Solution Approach 1:
The patent optimizes voltage and frequency parameters delivered to loads by converting through a DC intermediate stage. This allows precise control of output voltage to match actual load requirements rather than delivering excessive voltage, thereby reducing energy consumption and thermal losses while maintaining adequate power delivery.
Solution Approach 2:
The system incorporates control mechanisms that monitor load conditions and adjust power conversion parameters accordingly. This feedback control ensures voltage and frequency are optimized for actual load requirements, preventing excessive power delivery and associated energy losses.
3Loss of energy
If impedance is reduced to lower energy consumption, then power factor improves, but control complexity increases
Solution Approach 1:
The patent achieves improved power factor and reduced energy consumption by dynamically optimizing voltage and frequency parameters through controlled power conversion. The multistage conversion system allows independent control of voltage magnitude and frequency, enabling impedance optimization without requiring complex additional control circuitry beyond the power conversion stages themselves.
Data Source
AI summary
A power conversion system comprises a DC element, a source inverter interfacing an AC source and the DC element, a load inverter interfacing a load on the DC element and a controller. Voltage of an output of the load inverter is controlled by a controller to reduce power consumption according to a variable charge state of the DC element.