Power Converter System for Grid-Isolated Critical Load Management
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Solution Overview
Problem
Existing solar energy systems for grid-tied and off-grid applications face challenges in efficiently managing power distribution during brownouts or blackouts, where safety issues arise from energy being inadvertently fed into the power grid, and there is a need for intelligent load management to prioritize power delivery to critical loads.
Innovation Solution
A power converter system with a DC-to-AC converter, selective couplings, and a controller that determines the availability of the power grid and adjusts power delivery to AC loads based on load characteristics and available power, isolating the system from the grid during outages and prioritizing power to critical loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solar energy systems are connected to the power grid during brownouts or blackouts, then power can be supplied to loads, but safety hazards arise from energy backfeed into the grid
Solution Approach 1:
The system dynamically switches between grid-connected mode and islanded mode based on grid status detection. The controller monitors grid conditions and automatically reconfigures the coupling between the solar power system and the grid, enabling seamless transition to maintain power supply while preventing unsafe backfeed conditions
Solution Approach 2:
The power converter system acts as an intermediary between the solar power source and the grid, incorporating intelligent control logic that detects grid status and manages power flow direction. This intermediary function prevents direct connection during unsafe conditions while maintaining power supply to critical loads
2Object-affected harmful factors
If solar energy systems are isolated from the power grid during outages, then safety is improved, but power supply to loads cannot be maintained
Solution Approach 1:
The system dynamically adjusts its operational mode based on real-time grid status. When grid isolation is detected, the controller automatically switches to islanded operation, reconfiguring the power flow path to maintain supply to connected loads while ensuring physical or electrical isolation from the grid
Solution Approach 2:
The power converter system is designed to perform multiple functions: it can operate in grid-connected mode for normal power supply, switch to islanded mode for outage protection, and provide intelligent load management. This multi-functionality resolves the contradiction by adapting to different operational requirements
3Reliability
If power is distributed to all AC loads during grid outages, then power supply coverage is maximized, but energy efficiency decreases due to limited solar power availability
Solution Approach 1:
The system applies different power supply strategies to different loads based on their characteristics and priority. Critical loads receive priority power supply while non-critical loads are managed differently, optimizing the limited solar power resources to maintain essential functions without wasting energy on non-essential consumption
Solution Approach 2:
The controller continuously monitors the available solar power and the power consumption of connected loads, using feedback signals to adjust the coupling state and power distribution. This closed-loop control ensures that power is allocated efficiently according to actual availability and demand patterns
4Loss of energy
If selective coupling is implemented to manage power distribution, then energy efficiency improves, but device complexity increases
Solution Approach 1:
The selective coupling functionality is integrated into the existing power converter system, combining the grid connection control, load management, and power optimization functions into a unified controller. This merging approach achieves intelligent power distribution without proportionally increasing system 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
Enhances safety by preventing energy backfeed into the grid during repairs, optimizes power distribution to ensure continuous operation of critical loads, and improves energy efficiency by selectively providing power from solar energy sources.
Implementation Method 1
A DC-to-AC power converter configured to receive DC power from at least one DC power source
Data Source
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AI summary
A power converter system includes a power converter system including: a DC-to-AC power converter; a first output configured to be coupled to a power grid; a first input configured to be coupled to the power grid; second outputs each configured to be coupled to a corresponding AC load; a power-grid switch coupled to the converter and to the first output; load switches coupled to the converter, the second outputs, and the first input; and a controller coupled to the load switches and to the first output and configured to determine whether energy from the power grid satisfies at least one criterion, the controller being further configured to control the power-grid switch and the load switches to couple the converter to the first output and to couple the first input to the second outputs if the at least one criterion is satisfied and otherwise to control the power-grid switch and the load switches to isolate the converter from the first output and to couple the converter to at least one of the second outputs.