Hybrid Microgrid DC-Link Control for Converterless Solar PV
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Solution Overview
Problem
Existing hybrid renewable energy systems face challenges in efficiently integrating photovoltaic (PV) panels, wind turbines, and energy storage systems due to complex control mechanisms, lack of a third energy resource, and inefficient power management, leading to instability and high costs.
Innovation Solution
A hybrid grid-connected system (HGCS) incorporating a solar PV system, wind power generation, battery energy storage system (BESS), and a fuel cell system with an electrolyzer, managed by a controller that optimizes power transmission and storage using a DC-link and power electronic converters to stabilize the grid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If converter-based PV integration is used, then power transmission efficiency is improved, but system complexity and cost increase
Solution Approach 1:
The patent extracts the converter from the PV integration path by directly connecting PV panels to the DC-link, eliminating unnecessary power conversion stages. This reduces system complexity and cost while maintaining efficient power transmission through direct DC coupling.
Solution Approach 2:
The DC-link serves multiple functions: it directly accepts PV power, wind power through the DFIG, battery storage, and fuel cell integration. This multi-functional approach eliminates the need for separate converters for each source, reducing overall system complexity while maintaining efficiency.
2Reliability
If multiple energy sources are integrated, then system reliability is improved, but control complexity increases
Solution Approach 1:
The patent merges all energy sources (PV, wind DFIG, battery, fuel cell) into a common DC-link architecture. This unified structure simplifies control by providing a single point of integration, reducing the complexity of coordinating multiple independent systems while enhancing reliability through diverse energy sources.
Solution Approach 2:
The DC-link acts as an intermediary that harmonizes power from different sources with varying characteristics. It provides a common platform that naturally manages the integration complexity, allowing each energy source to operate independently while contributing to the unified system.
3Stability of the object's composition
If DC-link voltage stabilization is enhanced, then power quality is improved, but system responsiveness may be reduced
Solution Approach 1:
The system performs preliminary action by pre-charging the DC-link to a stable voltage level before full operation begins. This preliminary stabilization ensures that when full power transmission starts, the voltage is already conditioned, maintaining both stability and rapid responsiveness without trade-off.
Solution Approach 2:
The control system continuously monitors DC-link voltage and provides real-time feedback to adjust power flow from various sources. This feedback mechanism maintains voltage stability while allowing rapid response to changing conditions, as the system can dynamically balance power input and output without mechanical delays.
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 stable and reliable power supply by minimizing DC-link voltage fluctuations, optimizing energy storage, and ensuring consistent power delivery to the grid, even under varying weather conditions, thus enhancing system reliability and efficiency.
Implementation Method 1
a primary source comprising a solar photovoltaic (PV) system
Implementation Method 2
a wind power generation system
Implementation Method 3
a battery energy storage system (BESS)
Implementation Method 4
a tertiary source comprising a fuel cell system
Implementation Method 5
a fuel cell system operatively connected to an electrolyzer system
Data Source
AI summary
A device and method for managing power transmission to a power grid from a Hybrid Grid Connected System (HGCS) is presented. The HGCS includes a plurality of energy resources, including of solar photovoltaic cells (PV), wind power generation, a battery energy storage system (BESS) and a fuel cell system paired with an electrolyzer. Energy sources are connected by a DC-link to a power electronic converter which supplies power to the power grid. A controller is configured to calculate the total power, maximize transmission of power to the power grid from the primary sources, supply the net power to the power grid from the fuel cell system and use the power generated by the PV system and the wind power system for charging the BESS and powering the electrolyzer system based on the relative state of charge of the BESS and the voltage of the DC-link.