Microgrid Variable Frequency Control During Grid Outages
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Solution Overview
Problem
Grid-tied renewable energy systems shut down during grid outages, violating safety codes and preventing power generation from secondary sources, and existing systems lack flexibility in frequency adjustment to match varying load demands.
Innovation Solution
A microgrid system with an adapter and power controller that disconnects from the grid during outages, allowing independent operation and frequency adjustment to match load demands using variable frequency electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grid-tied inverter systems are used to connect secondary energy sources to the electrical grid, then power can be distributed to the grid, but the system must shut down during grid outages to prevent back-feeding de-energized grids
Solution Approach 1:
The system is divided into separate functional modules: grid-tied inverter for normal operation, variable frequency electronics for independent operation, and control circuitry for transition management. This segmentation allows each module to operate independently based on grid availability, enabling continuous power supply while maintaining safety during outages.
Solution Approach 2:
The system dynamically switches between grid-tied mode and independent variable frequency mode based on grid status. The control circuitry monitors grid availability and automatically adjusts operating parameters, allowing the system to adapt its frequency output to match load requirements during independent operation while preventing back-feeding during outages.
2Adaptability or versatility
If fixed frequency power supply is used to match grid frequency, then grid synchronization is maintained, but frequency cannot be adjusted to match varying load demands
Solution Approach 1:
The variable frequency electronics modify the frequency parameter of the power output based on load requirements. During independent operation, the system changes frequency from the fixed grid frequency (50/60 Hz) to optimized values that match the operational characteristics of connected loads, improving overall system efficiency and adaptability.
3Productivity
If variable frequency operation is implemented to match load demands, then energy efficiency is improved, but system complexity increases
Solution Approach 1:
The control circuitry serves multiple functions: monitoring grid status, managing transitions between operating modes, and adjusting frequency parameters. This multi-functionality reduces the need for separate dedicated components for each control task, thereby limiting the increase in system complexity while achieving variable frequency operation.
Data Source
AI summary
A micro grid system comprises an adapter and a power controller. The adapter is in communication with an electric grid and configured to connect and disconnect a connection between the electric grid and a micro grid. The power controller is electrically connected to the adapter and receives first AC power from the electric grid via the adapter, obtains grid information, and controls the adapter to connect and disconnect the connection between the electric grid and the micro grid. The power controller controls the adapter to disconnect the connection between the electric grid and the micro grid in response to determining that the electric grid is abnormal based on the grid information.