PV Inverter Threshold Control to Prevent Repeated Grid Switching
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Solution Overview
Problem
Inverters frequently switch between standby and grid-connected states due to low energy generation from photovoltaic panels, leading to increased power consumption and reduced service life of electrical components.
Innovation Solution
The inverter is controlled to operate in an off-grid state when the direct-current voltage exceeds a threshold, consuming energy from the photovoltaic array through adjustments to the power conversion circuit or temperature regulation system parameters, and switches to grid-connected state when predetermined conditions are met, including direct-current voltage and power thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inverter operates in grid-connected state when photovoltaic energy generation is low, then the inverter can maintain grid connection, but the inverter frequently switches between standby and grid-connected states, increasing power consumption and reducing service life of electrical components
Solution Approach 1:
The controller performs preliminary assessment of photovoltaic array output before allowing grid connection. It detects whether the output meets the threshold requirement in advance, and only permits transition to grid-connected state when conditions are satisfied, thereby avoiding frequent switching and reducing wear on electrical components
Solution Approach 2:
The controller continuously monitors the output of the photovoltaic array and uses feedback control to determine whether to maintain grid-connected state or switch to standby state. When the output falls below the threshold, the controller receives feedback and switches to standby state, preventing unnecessary switching cycles and reducing power consumption
2Adaptability or versatility
If the inverter switches frequently between standby and grid-connected states, then the inverter can adapt to low energy generation conditions, but the frequent switching increases power consumption and reduces service life of electrical components
Solution Approach 1:
The patent introduces a threshold parameter for photovoltaic array output. The controller changes the operational state of the inverter based on whether the output parameter meets this threshold. This parameter-based control strategy enables the system to adapt to low energy generation conditions while avoiding frequent switching by establishing a clear decision boundary
3Reliability
If the inverter requires higher photovoltaic output for grid connection, then frequent switching is reduced, but the inverter may fail to connect when energy generation is marginal
Solution Approach 1:
The controller requires the photovoltaic array output to exceed a threshold value (partial action) before permitting grid connection. This ensures that the system only connects when there is sufficient energy to maintain stable operation, preventing marginal connections that would lead to frequent disconnections and improving overall connection stability
Data Source
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AI summary
An inverter, a grid-connected control method, a photovoltaic system, an apparatus, and a medium are provided. The inverter includes: a power conversion circuit and a controller. The controller is configured to, in a case that the inverter operates in a standby state, control the inverter to operate in an off-grid state when a direct-current voltage of the inverter is greater than a voltage threshold, and adjust an off-grid operation parameter of the power conversion circuit in the inverter or an operation parameter of a temperature regulation system in an inverter cabinet. The controller is configured to, when the inverter meets at least one predetermined condition, control the inverter to operate in a grid-connected state. The predetermined condition includes: the direct-current voltage, an alternative-current voltage, an alternative-current current, a direct-current current, a direct-current side power or an alternative-current side power of the inverter being greater than a corresponding threshold. With the solutions in the present disclosure, the inverter is prevented from switching back and forth between the standby state and the grid-connected state multiple times, reducing power consumption and extending service lives of electrical components.