UPS Bypass Control for Variable Loads Without Grid Overload
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Solution Overview
Problem
Existing uninterruptible power supply systems struggle to manage variable loads that exceed the maximum power supply of the grid without causing grid collapse or incurring penalties, necessitating costly infrastructure upgrades.
Innovation Solution
A method for controlling an uninterruptable power supply system that includes a DC link connecting a rectifier to the grid and an inverter to the load, with a switchable bypass, allowing for dynamic power management through a control device that monitors and balances power supply and demand, utilizing energy storage and multiple converter modes to stabilize the grid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the grid connection is upgraded to supply higher power to variable loads, then the power supply capacity is improved, but the cost and complexity of infrastructure increases
Solution Approach 1:
The patent introduces an uninterruptible power supply (UPS) system as an intermediary device between the grid and the variable load. The UPS includes a rectifier, inverter, and energy storage unit that can buffer and regulate power flow, allowing the existing grid infrastructure to supply higher power demands without upgrading the grid itself. The UPS acts as a mediator that decouples the load power demands from the grid supply capacity.
Solution Approach 2:
The patent employs energy storage units that are charged in advance during periods of low demand or surplus power availability. This preliminary charging action allows the system to draw from stored energy when peak power demands occur, avoiding the need for continuous high-capacity grid infrastructure. The control device manages charge/discharge cycles to prepare energy reserves before peak loads occur.
2Reliability
If a fuse is arranged between the load and the grid to prevent overload, then grid protection is improved, but the reliability of power supply deteriorates due to permanent disconnection
Solution Approach 1:
The UPS system serves as an intermediary protective device that replaces the traditional fuse-based protection. Instead of permanently disconnecting the load via a fuse when overload occurs, the UPS control device manages power flow to prevent grid overload while maintaining continuous power supply to the load. The energy storage unit provides a buffer that allows the system to handle transient overloads without triggering protective disconnection.
Solution Approach 2:
The energy storage unit in the UPS system provides a cushioning effect by storing energy in advance. When power demands fluctuate or exceed grid capacity temporarily, the pre-charged energy storage unit can supplement the grid supply, preventing overload conditions that would otherwise trigger fuse disconnection. This beforehand cushioning maintains power supply continuity while protecting the grid.
3Quantity of substance
If the transformer power is greater than the load power, then energy surplus is available, but the energy storage unit charging efficiency may be limited by rectifier capacity
Solution Approach 1:
The patent employs a dynamic control device that continuously monitors and adjusts the operation of the rectifier and inverter based on real-time power conditions. When energy surplus is available, the control device dynamically optimizes the rectifier's charging rate within its capacity limits, and manages the inverter's power factor correction to maximize the utilization of available surplus energy for charging the energy storage unit. The system adapts its operation to changing load and grid conditions.
Solution Approach 2:
The control device changes operational parameters such as the rectifier's power conversion rate, the inverter's reactive power compensation level, and the charging voltage/current to the energy storage unit based on the available energy surplus and component capacity constraints. By dynamically adjusting these parameters, the system optimizes charging efficiency within the physical limits of the rectifier and other components.
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
Enables efficient power distribution to variable loads while preventing grid overload, optimizing energy flow, and ensuring seamless transitions between power sources, even during grid failures, thus avoiding costly upgrades and penalties.
Implementation Method 1
a rectifier (116) connected to the grid (102) via a grid switch (114)
Implementation Method 2
an inverter (118) connected to the load (104)
Implementation Method 3
an energy storage (122) connected to the DC link (120)
Data Source
Figure 1
Figure 2
AI summary
A method for controlling an uninterruptable power supply (100) arranged between a grid (102) and a variable load (104), the uninterruptable power supply (100) comprising a DC link (120) interconnecting a rectifier (116) connected to the grid (102) via a grid switch (114), an energy storage (122) and an inverter (118) connected to the load (104), and a switchable bypass (126) connected between the grid switch (114) and the load (104) and in parallel with the path formed by the rectifier (116), the DC link (120) and the inverter (118), the method comprising: monitoring a power supply (110) of the grid (102); comparing the power supply (110) to a load requirement (108) of the load (104); if the power supply (110) meets the load requirement (108), closing the grid switch (114); and switching on the bypass (126), to supply the load (104) with AC current from the grid (102).