18-Pulse Rectifier Backup Power Supply for Grid Harmonic Mitigation
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Solution Overview
Problem
There is a need for a clean backup power supply that can provide stable and efficient power without harming the utility grid, particularly for applications requiring constant voltage and frequency, and capable of ride-through during voltage sags and brown-outs.
Innovation Solution
A system utilizing an 18-pulse diode rectifier to convert raw AC power to a DC bus, which is then fed to an inverter to create a clean AC bus, connected to a battery via a DC-DC converter, ensuring minimal voltage and frequency fluctuations and harmonic distortion, with optional engine-generator backup and harmonic mitigating rectifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional backup power systems are used, then power availability is improved, but harmonic distortion and grid contamination occur
Solution Approach 1:
The patent employs an 18-pulse rectifier system that utilizes phase-shifted pulsing to minimize harmonic distortion. By dividing the rectification into multiple pulses with specific phase shifts, the system reduces the amplitude of harmonic currents injected into the utility grid, thereby resolving the contradiction between maintaining power availability and reducing grid contamination.
Solution Approach 2:
The patent introduces a DC bus as an intermediary between the rectifier and inverter stages. This DC bus decouples the AC input from the AC output, allowing independent optimization of each stage and enabling the system to provide clean power output while minimizing harmonic distortion on the utility side.
2Reliability
If clean power conversion is implemented, then power quality is improved, but system complexity increases
Solution Approach 1:
The patent designs the backup power system with multi-functional components that perform multiple operations. The 18-pulse rectifier simultaneously provides power conversion and harmonic mitigation, while the DC bus serves as both an energy storage element and a decoupling medium. This multi-functionality reduces the need for additional specialized components, thereby managing system complexity while maintaining high power quality.
3Reliability
If battery energy storage is added, then ride-through capability is improved, but energy consumption increases
Solution Approach 1:
The patent implements a battery energy storage system that is pre-charged during normal utility operation. This preliminary charging action ensures that energy is stored in advance, allowing the system to provide ride-through capability during utility disruptions without requiring continuous high energy consumption. The battery acts as a pre-prepared energy reservoir that activates only when needed.
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 system provides a reliable, clean power supply with minimal harmonic distortion and high availability, capable of ride-through during utility disruptions, while preventing costly 'clean energy' consumption on the grid and maintaining industry-standard distortion levels.
Implementation Method 1
an 18-pulse diode rectifier to convert raw AC power to a DC bus
Implementation Method 2
the DC bus, created from the diode bridges, to feed an inverter to supply a Clean AC Bus
Implementation Method 3
The DC Bus is connected to a DC-to-DC converter to a large Utility scale battery
Implementation Method 4
to ensure the synthetic AC Clean Bus has some kW as well as kVAR to fill in for voltage sags and brown-outs
Data Source
AI summary
A system and method for providing a backup power supply.