Reactive Power Compensation for Grid Voltage Stability

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Solution Overview

Problem

In wind power generation systems with power storage devices, the connection of filter capacitors to the grid during low wind conditions or power conversion circuit stoppages leads to undesirable voltage rises at the grid connection point, and frequent circuit breaker tripping to mitigate this issue results in excessive opening and closing, which is inefficient.

Innovation Solution

A wind power generation system with a power storage device that includes a wind power generator, a first power conversion circuit, a filter capacitor, a circuit breaker, and a second power conversion circuit with a control system for reactive power compensation, where the second power conversion circuit receives reactive power from the filter capacitor when the first power conversion circuit is stopped, thereby suppressing voltage rises without frequent circuit breaker activation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the circuit breaker is tripped each time the power conversion circuit stops, then the voltage rise can be suppressed, but the frequency of opening and closing of the circuit breaker becomes too high

Engineering Contradiction:

Improvevoltage rise at grid connection pointVSAvoidcircuit breaker operation frequency

Core Design Contradiction:

Object-affected harmful factorsVSDuration of action of moving object

Solution Approach 1:

The patent introduces a reactive power compensator as an intermediary device between the filter capacitor and the grid connection point. This compensator actively manages the reactive power flow to counteract the voltage rise effect of the filter capacitor, thereby suppressing voltage rise without requiring the circuit breaker to open. The reactive power compensator acts as a mediator that resolves the harmful effect while keeping the circuit breaker closed.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the operational parameters of the system by dynamically adjusting the reactive power output of the reactive power compensator based on the status of the power conversion circuit. When the power conversion circuit stops, the compensator increases its reactive power output to counteract the filter capacitor's voltage rise effect. This parameter adjustment allows voltage control without mechanical circuit breaker operation.

Inventive Principle:

Principle #35Parameter changes

2Duration of action of moving object

If the circuit breaker is kept connected during power conversion circuit stoppage, then the frequency of opening and closing is reduced, but the voltage at the grid connection point rises due to the filter capacitor

Engineering Contradiction:

Improvecircuit breaker operation frequencyVSAvoidvoltage rise at grid connection point

Core Design Contradiction:

Duration of action of moving objectVSObject-affected harmful factors

Solution Approach 1:

The reactive power compensator serves as an intermediary that actively counteracts the voltage rise effect of the filter capacitor. By dynamically adjusting its reactive power output, it neutralizes the harmful voltage rise while allowing the circuit breaker to remain connected, thus reducing mechanical wear and improving system reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful reactive power output of the filter capacitor (which causes voltage rise) into a beneficial effect by using the reactive power compensator to absorb or counteract this reactive power. The compensator transforms the problematic reactive power flow into a controlled parameter that can be used to maintain voltage stability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

The system effectively suppresses voltage rises at the grid connection point by using reactive power compensation, reducing the need for frequent circuit breaker operations and maintaining grid stability during low wind conditions.

Implementation Method 1

reactive power compensation operation in a state in which the filter capacitor is connected to the grid connection point by making the circuit breaker connected and the first power conversion circuit is stopped, the reactive power compensation operation being an operation in which the second power conversion circuit receives reactive power from the filter capacitor via the grid connection point

Methodology Applied

Scientific EffectReactive power compensation: Capacitance

Data Source

PatentUS11336097B2Wind power generation system with power storage device

Publication Date: 2022.05.17 TMEIC CORP

AI summary

A wind power generation system with a power storage device includes a wind power generation system, a power storage device system, and a reactive power controller. The wind power generation system includes a wind power generator, a first power conversion circuit, a first control circuit, a first filter capacitor, and a circuit breaker interposed between the first filter capacitor and a grid connection point. The wind power generation system is configured to output the electric power converted by the first power conversion circuit to an electric power grid via the grid connection point. The power storage device system includes a power storage device, a second power conversion circuit, and a second control circuit that controls the second power conversion circuit to perform load leveling operation. The reactive power controller causes the second power conversion circuit to perform reactive power compensation operation.