Photovoltaic Power Conditioning Circuit Grid Islanding Prevention
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Solution Overview
Problem
Existing power supply circuits from photovoltaic devices to domestic grid mains face challenges in maintaining power quality and preventing 'islanding', where the PV inverter continues to supply power during grid disruptions, requiring rapid disconnection within 5 seconds.
Innovation Solution
A photovoltaic power conditioning circuit with a DC-to-AC converter and an electronic controller directly coupled to the mains power supply line, monitoring voltage and current to control the converter, ensuring disconnection when the grid is tripped and maintaining power quality by adjusting frequencies and voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If discrete electronic components are used to convert low DC input voltage to high AC output voltage, then power conversion functionality is achieved, but device complexity increases
Solution Approach 1:
The patent combines multiple discrete electronic components into an integrated power conversion circuit that can convert low DC voltage to high AC voltage in a unified structure, reducing overall device complexity while maintaining power conversion functionality
Solution Approach 2:
The inverter circuit is designed to perform multiple functions including voltage conversion, frequency conversion, and grid synchronization within a single system, eliminating the need for separate discrete components for each function
2Duration of action of stationary object
If the PV inverter continues to supply power during grid disruptions, then power availability is maintained, but safety hazards increase due to islanding
Solution Approach 1:
The electronic controller directly coupled to the power supply line continuously monitors voltage and current conditions and provides feedback to the DC-to-AC converter, enabling rapid detection of grid disruptions and automatic disconnection to prevent islanding while maintaining power supply continuity during normal operation
Solution Approach 2:
The system performs preliminary monitoring of grid conditions through direct coupling of the controller to the power supply line, detecting potential islanding conditions before they become hazardous and initiating disconnection in advance to ensure safety
3Reliability
If the controller is indirectly coupled through the power conversion circuit, then isolation is provided, but measurement precision decreases
Solution Approach 1:
The patent introduces direct coupling of the electronic controller to the power supply line as an intermediary measurement path, allowing accurate voltage and current sensing without compromising the electrical isolation provided by the power conversion circuit, thereby maintaining both reliability and measurement precision
4Stability of the object's composition
If disconnection time is extended beyond 5 seconds, then system stability is maintained, but compliance with regulatory standards deteriorates
Solution Approach 1:
The system performs preliminary detection of grid disruptions through direct controller coupling to the power supply line, enabling rapid response that achieves disconnection within the 5-second regulatory requirement while maintaining system stability through controlled shutdown procedures
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
Ensures reliable and safe disconnection from the grid during outages, preventing islanding and maintaining power quality by directly monitoring and controlling the mains supply conditions, thus adhering to regulatory standards.
Implementation Method 1
power from a photovoltaic device
Implementation Method 2
a DC-to-AC converter coupled to said DC input and to said AC output to convert DC power from said photovoltaic device to AC power
Data Source
AI summary
This invention is generally concerned with power supply circuits, and more particularly, with circuits to supply power to a mains supply, such as domestic grid mains, from a photovoltaic device. A photovoltaic power conditioning circuit for providing power from a photovoltaic device to an alternating current mains power supply line, the circuit comprising: a DC input to receive DC power from said photovoltaic device; an AC output configured for direct connection to said AC mains power supply line; a DC-to-AC converter coupled to said DC input and to said AC output to convert DC power from said photovoltaic device to AC power for output onto said power supply line; and an electronic controller directly coupled to said power supply line to measure a voltage of said power supply line and a current in said supply line and to control said DC-to-AC converter responsive to said measuring.