Solar String Shutoff Architecture for Stable Low-Power Switching
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Solution Overview
Problem
The existing solar power generation systems face challenges in reducing installation costs of shutoff devices while ensuring stability, particularly due to the reliance on mechanical switching devices that can be unstable when power generation is low or unstable, leading to repeated switching and operational instability.
Innovation Solution
A solar power generation system is designed with a master-slave configuration of shutoff devices, where the first shutoff device, driven by power from solar cell modules, controls the second shutoff device via a communication system separate from power line communication, using semiconductor switching devices to stabilize operations and reduce installation costs by simplifying the second shutoff device's configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shutoff device is installed for each solar cell module to improve firefighter safety, then the safety of firefighters is improved, but the installation cost of shutoff devices increases
Solution Approach 1:
The solar cell modules are divided into multiple groups (first group, second group, third group, etc.), and shutoff devices are installed at the group level rather than at each individual module. This segmentation approach maintains safety by ensuring that shutoff functionality is distributed throughout the system while reducing the total number of shutoff devices required, thereby lowering installation costs.
Solution Approach 2:
A communication line acts as an intermediary to transmit control signals between shutoff devices. The first shutoff device receives control signals from an external controller and transmits them to the second shutoff device via the communication line, enabling coordinated shutoff operation across multiple groups without requiring each device to be independently controlled, thus reducing system complexity and cost.
2Ease of manufacture
If a mechanical switching device is used to cut off electric paths, then the shutoff function is achieved, but the system stability deteriorates when power generation is low or unstable
Solution Approach 1:
The patent replaces purely mechanical switching devices with a hybrid system that incorporates semiconductor switching devices. The semiconductor switching device is turned on before the mechanical contact closes, providing electrical support that prevents the mechanical switch from oscillating when power generation is low or unstable. This substitution maintains the shutoff function while significantly improving system stability.
Solution Approach 2:
The semiconductor switching device is activated in advance before the mechanical contact of the switching device closes. This preliminary action ensures that the electrical path is already supported by the semiconductor device, preventing instability and repeated switching that would occur if the mechanical contact closed without prior electrical support.
3Device complexity
If the switching device is driven by power from solar cell modules, then the system simplicity is improved, but the switching stability worsens when power generation is insufficient
Solution Approach 1:
The switching device employs a composite structure combining a mechanical switching element and a semiconductor switching element. The mechanical contact provides the primary shutoff function, while the semiconductor switching device provides stable electrical control and support. This composite approach maintains system simplicity by using a single integrated switching device while eliminating the instability caused by insufficient power generation.
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
This configuration reduces the occurrence of unstable switching, stabilizes the operation of the solar power generation system, and decreases the installation cost of shutoff devices by ensuring reliable and efficient power management even at low or unstable power generation levels.
Implementation Method 1
The string includes a plurality of solar cell module groups connected in series with each other. The plurality of solar cell module groups each include one or a plurality of solar cell modules connected in series.
Data Source
AI summary
A solar power generation system includes a string, an inverter, a first shutoff device, and a second shutoff device. The string includes a plurality of solar cell module groups. The first shutoff device cuts off connections between the plurality of solar cell module groups connected to a first electric path, in response to a first control signal. The second shutoff device cuts off connections between the plurality of solar cell module groups connected to a second electric path, in response to a second control signal output from the first shutoff device by a communication system different from power line communication. A first switching unit of the first shutoff device includes a first open and close unit and a first semiconductor switching device connected in parallel with the first open and close unit. The first semiconductor switching device is turned ON before the first open and close unit is operated.