UPS Reactive Power Control via Partial Compensation
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Solution Overview
Problem
Existing uninterruptible power supplies (UPS) require high capacity and increased costs to compensate large reactive power generated at loads, leading to apparatus upsizing.
Innovation Solution
A UPS configuration that includes a converter, inverter, controller, and limiter to control and limit reactive power generated at the converter, allowing compensation within the rated capacity by setting an upper limit based on the difference between the UPS's rated capacity and the AC power supplied to the load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reactive power generated at the load is wholly compensated with reactive power generated at the uninterruptible power supply, then the power factor is controlled to 1, but the uninterruptible power supply requires high capacity causing apparatus upsizing and increase in cost
Solution Approach 1:
The patent applies partial action by having the uninterruptible power supply compensate only a portion of the reactive power generated at the load, rather than wholly compensating it. The controller limits the reactive power generated at the converter to a predetermined upper limit value, achieving partial compensation that improves power factor without requiring the UPS to provide full reactive power support, thus avoiding apparatus upsizing.
2Reliability
If reactive power generated at the load is wholly compensated with reactive power generated at the uninterruptible power supply, then the power factor is controlled to 1, but the cost increases
Solution Approach 1:
The patent applies partial action by having the uninterruptible power supply compensate only a portion of the reactive power generated at the load, rather than wholly compensating it. The controller limits the reactive power generated at the converter to a predetermined upper limit value, achieving partial compensation that improves power factor without requiring the UPS to provide full reactive power support, thus avoiding apparatus upsizing.
3Reliability
If reactive power generated at the load is wholly compensated with reactive power generated at the uninterruptible power supply, then the power factor is controlled to 1, but the apparatus size increases
Solution Approach 1:
The patent applies partial action by having the uninterruptible power supply compensate only a portion of the reactive power generated at the load, rather than wholly compensating it. The controller limits the reactive power generated at the converter to a predetermined upper limit value, achieving partial compensation that improves power factor without requiring the UPS to provide full reactive power support, thus avoiding apparatus upsizing.
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 enables reactive power compensation within the rated capacity, reducing the need for high-capacity UPS systems and lowering costs while maintaining effective power factor control.
Implementation Method 1
a converter configured to convert AC power from the AC power source into DC power
Implementation Method 2
an inverter configured to convert DC power generated by the converter or DC power in a power storage device into AC power to supply the converted power to a second load
Data Source
AI summary
An uninterruptible power supply is configured to receive, together with a first load, AC power supplied from an AC power source. The uninterruptible power supply includes: a converter configured to convert AC power from the AC power source into DC power; an inverter configured to convert DC power generated by the converter or DC power in a battery into AC power to supply the converted power to a second load; a controller configured to control reactive power generated at the converter to compensate at least a part of reactive power generated at the first load; and a limiter configured to limit reactive power generated at the converter to upper limit power or lower. The upper limit power is set to a value according to the difference between the rated capacity of the uninterruptible power supply and AC power supplied to the second load.