Shared Grid Switch Control for Multi-Channel Power Conversion
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Solution Overview
Problem
In multi-channel grid-connected power generation systems, the high hardware cost of providing separate switching devices and control units for each branch leads to excessive no-load losses when energy conversion devices become non-operational, as existing solutions are designed for single-channel systems.
Innovation Solution
A multi-channel grid-connected power generation system where multiple energy conversion devices are connected in parallel, sharing a single switching device and control unit, with the control unit managing the switching device to disconnect from the grid when energy conversion devices are non-operational, and at least one device operates as a voltage source to stabilize voltage differences before reconnecting to the grid, allowing other devices to act as current sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If one switching device and one control unit are separately provided for each grid-connected branch, then the no-load loss of each step-up transformer is reduced, but the hardware cost of the multi-channel grid-connected power generation system becomes too high
Solution Approach 1:
The patent merges multiple switching devices into a single shared switching device that controls the connection between the collector line and the power grid. This consolidation reduces hardware cost while maintaining the ability to disconnect transformers from the grid when not in use, thereby reducing no-load losses.
Solution Approach 2:
The single switching device and control unit are designed to serve multiple grid-connected branches simultaneously. The control unit can manage the switching state for all branches connected to the collector line, making these components universal rather than dedicated to individual branches, thus reducing overall hardware requirements.
2Loss of energy
If multiple switching devices are provided for each grid-connected branch, then the no-load loss is reduced, but the system complexity and hardware cost increase significantly
Solution Approach 1:
Multiple switching functions are merged into a single switching device located at the collector line. This device controls the connection for all step-up transformers simultaneously, reducing system complexity while maintaining the capability to isolate individual transformers from the grid to eliminate no-load losses.
Solution Approach 2:
The collector line acts as an intermediary between individual grid-connected branches and the power grid. By placing the switching device at this intermediate point, the system can control grid connection for multiple branches through a single switching action, simplifying the overall system architecture.
3Device complexity
If a single switching device is shared by multiple channels, then hardware cost is reduced, but the control complexity for voltage stabilization increases
Solution Approach 1:
The control system segments the multi-channel power generation system by having each energy conversion device operate independently as either a voltage source or current source. This segmentation simplifies control complexity by allowing decentralized control decisions while sharing the switching device, as each channel can autonomously determine its operational mode based on system needs.
Solution Approach 2:
The system dynamically adjusts the operational mode of each energy conversion device, switching between voltage source and current source modes based on real-time conditions. This dynamic adaptability allows the system to maintain voltage stabilization with a single switching device, as the operational characteristics of connected devices can be flexibly adjusted to compensate for the shared switching arrangement.
Data Source
AI summary
The present application discloses a multi-channel grid-connected power generation system and a control method therefor, which lowers the system cost while reducing no-load losses of all step-up transformers. Multi-channel energy conversion devices in the system are each connected in parallel, by means of a step-up transformer, to the same collector line, one end of the collector line is connected to the grid by means of a switch device, and the on-off switching of the switch device is controlled by a control unit. The control unit sends a switch-off command to the switch device when same has determined that all of the energy conversion devices have entered a non-operating state. In the off state of the switch device, at least one energy conversion device, when meeting a start-up condition, starts to operate as a voltage source, and establishes an alternating-current voltage, so that the phase difference and amplitude difference of voltages at two ends of the switch device are both stable within an allowable error range. Then, the control unit sends a switch-on command to the switch device, and the other energy conversion devices start to operate as a current source to transfer energy to the grid.