Renewable UPS Control for Grid Outage and Excess Power Storage
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Solution Overview
Problem
Conventional renewable power systems disconnect during grid failures, fail to provide reliable backup power, and lack control over power sources and storage, especially in terms of balancing renewable and utility power based on time, rates, and storage options.
Innovation Solution
An integrated uninterruptible power system (UPS) with a controller that manages power from various sources, including renewable energy and storage, to provide continuous power by determining grid operational status, routing power efficiently between sources, and optimizing energy storage based on utility rates and demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If renewable power systems are integrated with the utility grid, then excess power can be provided back to the grid, but the system must shut off during grid failure to prevent safety hazards
Solution Approach 1:
The system segments the power flow control into separate functional blocks: a first converter circuit for grid connection, a second converter circuit for load connection, and a control circuit for coordinating between them. This segmentation allows independent optimization of each function while maintaining overall system reliability.
Solution Approach 2:
The control circuit acts as an intermediary that monitors grid status and dynamically switches between grid-connected mode (for exporting excess power) and islanded mode (for providing backup power during failures). This intermediary coordination resolves the contradiction by enabling both energy utilization and safety.
2Adaptability or versatility
If a UPS circuit includes multiple converter circuits and control circuits, then power can be managed from multiple sources, but the device complexity increases
Solution Approach 1:
The converter circuits are designed with multi-functionality: the first converter circuit can operate in both rectification mode (charging batteries from grid) and inversion mode (powering load from batteries). The second converter circuit similarly handles both grid-to-load power transfer and isolation functions. This universality reduces the need for separate dedicated circuits for each function.
Solution Approach 2:
The control circuit merges multiple control functions into a single integrated unit: it monitors grid voltage and frequency, controls the first converter circuit's operation mode, manages the second converter circuit's power flow, and coordinates the switching between grid-connected and islanded modes. This consolidation simplifies the overall control architecture.
3Loss of energy
If the system provides excess power back to the grid, then energy utilization is improved, but the system loses control over power distribution during grid failures
Solution Approach 1:
The control circuit implements continuous feedback monitoring of grid status (voltage, frequency, presence) and dynamically adjusts the operation of both converter circuits based on real-time conditions. This feedback mechanism enables automatic transition between exporting excess power to the grid and providing isolated power control during failures, maintaining ease of operation throughout.
Data Source
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AI summary
An uninterruptible power supply (100) includes an input (134b, 134c) configured to be coupled to a renewable power source (138a, 138b) and an energy storage component (146) configured to receive and store energy and to provide stored power. Power circuitry (110, 150) is configured to receive the renewable power and the stored power and provide output power to a load (164). A controller (170) coupled to the power circuitry determines whether an amount of available renewable power exceeds the output power level provided to the load and, if so, provides excess power from the renewable power to the stored energy component.