PV Rapid Shutdown Startup via DC Bus Voltage Signaling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional rapid shutdown systems in grid-connected photovoltaic systems require additional receiving modules, leading to high hardware costs and potential interference issues, which affect the timely and efficient operation of the rapid shutdown device.
Innovation Solution
The method involves an inverter system regulating the voltage across a direct-current bus to communicate with the rapid shutdown device, allowing it to determine if a preset conduction condition is met, thereby eliminating the need for an additional receiving module and reducing hardware costs, while also preventing erroneous activations due to interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional receiving module is added to the rapid shutdown device to enable communication with the central controller, then the communication reliability is improved, but the hardware cost and device complexity increase
Solution Approach 1:
The patent merges the communication function into the existing voltage detection circuitry of the rapid shutdown device. The device uses its existing voltage sampling circuit to detect voltage changes on the DC bus, which serve as communication signals from the inverter system. This eliminates the need for a separate receiving module while maintaining reliable communication for shutdown activation.
Solution Approach 2:
The voltage sampling circuit of the rapid shutdown device is given a dual function: it continues to monitor DC bus voltage for overvoltage protection while simultaneously detecting communication signals from the inverter system. This multi-functionality eliminates the need for dedicated communication hardware, reducing device complexity and cost.
2Adaptability or versatility
If an additional receiving module is added to the rapid shutdown device, then the ability to receive shutdown commands is improved, but the hardware cost increases
Solution Approach 1:
The rapid shutdown device uses its own existing voltage detection circuitry to receive and process shutdown commands. The inverter system communicates by intentionally modulating the DC bus voltage, which the rapid shutdown device's voltage sampling circuit naturally detects. This self-service approach eliminates the need for separate communication hardware, reducing both cost and complexity.
Solution Approach 2:
The inverter system encodes communication signals by intentionally changing the voltage parameter of the DC bus. Instead of using separate communication channels, the system modulates the DC bus voltage with specific patterns that the rapid shutdown device can distinguish from normal operating voltages. This parameter-based communication eliminates the need for additional receiving modules.
3Device complexity
If voltage regulation is used for communication between the inverter system and rapid shutdown device, then the hardware cost is reduced, but the measurement precision requirement increases
Solution Approach 1:
The inverter system prepares communication signals by pre-modulating the DC bus voltage with distinct patterns before the rapid shutdown device needs to detect them. The voltage regulation creates clearly distinguishable voltage levels and transition patterns that simplify the detection task, reducing the precision requirements compared to detecting subtle signals in noisy environments.
Solution Approach 2:
The communication system uses deliberate, large-magnitude voltage changes on the DC bus to encode commands. These significant parameter changes create clear detection thresholds that are easy for the rapid shutdown device to distinguish from normal voltage variations, thereby reducing the measurement precision requirements while maintaining reliable communication.
Data Source
AI summary
A start method for a photovoltaic rapid shutdown system, an application apparatus and a system. In the method, an inverter system controls the voltage change of a corresponding direct current bus in a photovoltaic rapid shutdown system; and a photovoltaic module shutdown device performs determination according to a measured output voltage of itself, and controls itself to be turned on when the change characteristic of the voltage of the direct current bus connected to itself satisfies a preset turn-on condition. Therefore, merely by means of a self-contained voltage sampling device, the photovoltaic module shutdown device can determine whether a turn-on signal is received, without additionally providing a corresponding receiving device, thereby reducing hardware cost of the photovoltaic module shutdown device while realizing communication between the photovoltaic module shutdown device and the outside.