AVR Voltage Adjustment for Microgrid Stability

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Solution Overview

Problem

Microgrids face challenges in maintaining stability due to increased penetration of inverter-connected generation, leading to reduced system inertia and increased costs from oversizing rotating equipment to ensure stability, which results in inefficient operations and high capital and maintenance costs.

Innovation Solution

Implementing a control system that adjusts the voltage output of electrical generators based on measured frequency deviations, using automatic voltage regulators (AVRs) to emulate synthetic inertia, allowing for the use of smaller generators and reducing power consumption at end-use loads, thereby enhancing stability and reducing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If inverter-connected generation penetration is increased, then renewable energy integration is improved, but system inertia is reduced and dynamic stability deteriorates

Engineering Contradiction:

Improverenewable energy integrationVSAvoiddynamic stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent introduces an automatic voltage regulator (AVR) as an intermediary control device between the inverter-connected generation and the grid. The AVR modifies the voltage output response to emulate the inertial characteristics of synchronous generators, thereby maintaining system stability while allowing high penetration of inverter-based renewable energy sources.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the voltage regulation parameters dynamically in response to grid frequency deviations. By adjusting the voltage output according to measured frequency changes, the system emulates inertial response and maintains stability without requiring physical rotating mass, thus enabling high renewable penetration while preserving dynamic stability.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If rotating equipment is oversized to maintain stability, then dynamic stability is improved, but capital costs and maintenance costs increase

Engineering Contradiction:

Improvedynamic stabilityVSAvoidcapital costs

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent creates a synthetic copy of inertial behavior through control algorithms in the AVR. Instead of physically oversizing rotating equipment, the system copies the stabilizing effect of inertia through electronic control of voltage output, thereby maintaining stability without the capital cost of oversized generators.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical inertial response of oversized rotating equipment with an electronic control system. The AVR uses measured frequency deviations to adjust voltage output, substituting the mechanical inertia of large generators with an electronic control mechanism that achieves the same stability effect at lower capital cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Stability of the object's composition

If voltage output is temporarily reduced during transient events, then frequency deviations are minimized and stability is improved, but power delivery is reduced

Engineering Contradiction:

Improvefrequency stabilityVSAvoidpower delivery

Core Design Contradiction:

Stability of the object's compositionVSPower

Solution Approach 1:

The patent implements periodic voltage adjustment in response to transient events. The AVR temporarily modifies voltage output during frequency deviations and then restores normal voltage levels, creating a periodic control action that maintains stability while minimizing impact on power delivery. This allows the system to prioritize stability during transients and return to full power delivery during normal operation.

Inventive Principle:

Principle #19Periodic action

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 increases microgrid stability on a dynamic scale while reducing capital and operating costs by enabling the use of smaller, more efficiently operated generators, and minimizing frequency deviations during transient events.

Implementation Method 1

an automatic voltage regulator (AVR) is configured to adjust output voltage of the electrical generator by adjusting field excitation current of the electrical generator

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10784686B2Grid stabilization using adjusted voltage regulator response to grid characteristics

Publication Date: 2020.09.22 BATTELLE MEMORIAL INST

AI summary

Apparatus and methods are disclosed for control systems for improving stability of electrical grids by temporarily reducing voltage output of electrical generators responsive to transient events on an electrical grid. In one example of the disclosed technology, a controller is coupled is to an automatic voltage regulator, which in turn adjusts excitation current of an electrical generator responsive to changes in frequency detected for the electrical grid. Reducing the output voltage temporarily allows for smaller generators to provide power to the microgrid. Methods for selecting parameters determining how the controller generates a regulation signal used to adjust the excitation current are further disclosed.