Inverter Control for Photovoltaic Hiccup Reduction
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Solution Overview
Problem
Photovoltaic systems experience frequent disconnections from the electrical grid due to insufficient power output, leading to a 'hiccup phenomenon' that shortens the mechanical life of grid connection switches and reduces system reliability, with existing solutions increasing costs and volume by requiring additional DC loads.
Innovation Solution
A method and system that utilize an AC load connected to the photovoltaic system's inverter, where the AC load consumes power when the inverter is disconnected from the grid, allowing the inverter to reconnect when sufficient power is produced, without the need for additional DC loads, by controlling the AC interface to maintain disconnection, starting the inverter and AC load, and reconnecting to the grid when power output meets stability conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DC load is added to consume power and pull down output voltage to prevent hiccup phenomenon, then system reliability is improved, but device complexity and cost increase
Solution Approach 1:
The invention makes the inverter itself serve as the load by controlling it to operate in a state that consumes power from the photovoltaic output device. The inverter's internal circuitry and control system are utilized to create the necessary power consumption without requiring external DC load components, thereby improving reliability while avoiding increased device complexity
Solution Approach 2:
The inverter is designed to perform multiple functions: it not only converts DC to AC for grid connection but also serves as a power-consuming load during startup and low-light conditions. This multi-functionality eliminates the need for separate DC load components, resolving the contradiction between reliability improvement and device complexity
2Reliability
If a DC load is added to prevent hiccup phenomenon, then system reliability is improved, but volume increases
Solution Approach 1:
The invention merges the function of the DC load with the inverter itself. By controlling the inverter to operate in a power-consuming mode during critical periods, the separate DC load component is eliminated, thereby improving reliability without increasing system volume
3Productivity
If the inverter is connected to the grid immediately after startup, then productivity is improved, but the hiccup phenomenon occurs frequently due to insufficient power output
Solution Approach 1:
The invention implements preliminary action by controlling the inverter to operate in a power-consuming state before grid connection. This preliminary operation ensures that the photovoltaic output device has sufficient power capacity to support grid connection, preventing the hiccup phenomenon while still achieving timely system deployment
Solution Approach 2:
The system uses feedback control to monitor the power output of the photovoltaic output device and adjust the inverter's operation accordingly. When power output is sufficient, the inverter connects to the grid; when insufficient, it operates in a power-consuming mode, thereby balancing productivity and reliability
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 approach reduces the frequency of hiccup events, allows continuous operation, and avoids drawing power from the electrical grid, maintaining system stability without increasing costs or volume by eliminating the need for additional DC loads.
Implementation Method 1
a photovoltaic output device (100), an inverter device (200)
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Provided are a photovoltaic system and a method for controlling a photovoltaic system. The photovoltaic system includes a photovoltaic output device (100), an inverter device (200), an AC interface device (300), a control device (400) and an AC load (500), where a supply terminal of the AC load is connected to an AC output side of the inverter device, and a control terminal of the AC load is connected to the control device, and the method for controlling the photovoltaic system is applied to the control device. The method for controlling the photovoltaic system includes: controlling the AC interface device to maintain the inverter device being disconnected from an electrical grid (S21); starting the inverter device and then starting the AC load (S22); and controlling the AC interface device to connect the inverter device to the electrical grid, in a case that it is determined that a grid connection condition is met for the photovoltaic system (S23). With the photovoltaic system and the method for controlling a photovoltaic system, the number of occurrences of a hiccup phenomenon can be decreased without needing to provide a DC load additionally, and the cost and volume of the photovoltaic system are not increased. Furthermore, before the inverter device is connected to the electrical grid, the AC load can make full use of the power produced by the photovoltaic output device, and it is avoided to draw power from the electrical grid.