PV Inverter Off-Grid Buffering for Stable Grid Connection
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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 a grid-connected state only when predetermined conditions are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the inverter directly switches from standby state to grid-connected state when photovoltaic energy is low, then the inverter can quickly connect to the grid, but it causes frequent switching between states which increases power consumption and reduces component service life
Solution Approach 1:
The inverter performs preliminary energy consumption through off-grid operation before connecting to the grid. When photovoltaic energy is sufficient, the inverter first operates in off-grid mode to consume excess energy, then transitions to grid-connected mode. This preliminary action prevents immediate switching when energy is insufficient, reducing frequent state changes and extending component service life.
2Reliability
If the inverter operates in off-grid state to consume energy from photovoltaic array, then frequent switching is prevented and component service life is extended, but the energy consumption during the off-grid operation increases
Solution Approach 1:
The inverter changes operational parameters by switching between off-grid and grid-connected modes based on photovoltaic energy levels. When photovoltaic energy exceeds grid requirements, the inverter operates in off-grid mode with adjusted parameters to consume excess energy. This parameter change enables controlled energy consumption that prevents frequent switching while managing overall power consumption through intelligent control.
3Stability of the object's composition
If the inverter uses multiple parameter thresholds (voltage, current, power) for grid-connected operation, then stable operation is achieved and frequent switching is reduced, but the control system complexity increases
Solution Approach 1:
The inverter employs multiple parameter thresholds including direct-current voltage threshold, alternative-current voltage threshold, alternative-current current threshold, direct-current current threshold, direct-current side power threshold, and alternative-current side power threshold. By monitoring and comparing these parameters against predefined thresholds, the inverter makes stable switching decisions. This multi-parameter approach ensures stable operation by considering various electrical conditions, reducing frequent switching despite the increased control logic complexity.
Data Source
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.