Decentralized Optimal Inverter Dispatch for PV Voltage Regulation

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Solution Overview

Problem

The integration of photovoltaic (PV) systems into residential and commercial settings poses challenges related to power quality, efficiency, and reliability, particularly due to overvoltages during peak PV generation and voltage transients from varying atmospheric conditions, which existing inverter controls and protocols struggle to address effectively.

Innovation Solution

The implementation of decentralized optimal inverter dispatch (OID) techniques that determine active and reactive power setpoints for PV inverters, leveraging sparsity-promoting regularization and semidefinite relaxation, to optimize power distribution and enhance network resilience, reliability, and power quality, while allowing for ancillary services and flexible operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If PV inverters operate with standard protocols extracting maximum power at unity power factor, then productivity is improved, but power quality deteriorates due to overvoltages during peak PV generation

Engineering Contradiction:

Improvepower extractionVSAvoidovervoltages

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements dynamic control of inverter operation modes, transitioning between maximum power extraction and voltage regulation modes based on real-time system conditions. The secondary control layer dynamically adjusts reactive power injection to maintain voltage within acceptable ranges while maximizing active power extraction when conditions permit.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes operational parameters by adjusting the power factor and reactive power injection levels of PV inverters. By deviating from unity power factor operation when needed, the system can regulate voltage and prevent overvoltages while still maintaining high overall productivity through optimized active power extraction.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If PV inverters provide reactive power compensation for voltage regulation, then power quality is improved, but loss of energy increases due to high network currents

Engineering Contradiction:

Improvevoltage regulationVSAvoidpower losses

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The patent implements local voltage regulation at distribution level through PV inverter reactive power compensation, addressing voltage issues where they occur rather than through centralized control. This localized approach reduces the need for high network currents and associated power losses in transmission lines.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs feedback mechanisms where inverter controllers continuously monitor voltage levels and adjust reactive power injection accordingly. This closed-loop control ensures voltage regulation is provided only when and where needed, minimizing unnecessary reactive power flow and associated energy losses.

Inventive Principle:

Principle #23Feedback

3Reliability

If decentralized optimal inverter dispatch is implemented, then reliability is improved through optimized power distribution, but device complexity increases

Engineering Contradiction:

Improvenetwork resilienceVSAvoidinverter control

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the control architecture into two distinct layers: a primary control layer handling maximum power extraction and a secondary control layer handling voltage regulation and ancillary services. This segmentation allows each layer to operate independently with well-defined interfaces, improving reliability without requiring overly complex integrated control systems.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent designs PV inverter controllers with multi-functionality, capable of performing both maximum power extraction and voltage regulation/ancillary services through the two-layer control architecture. This universality reduces the need for separate dedicated devices for each function, managing complexity while enhancing network reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10139800B2Decentralized optimal dispatch of photovoltaic inverters in power distribution systems

Publication Date: 2018.11.27 REGENTS OF THE UNIVERSITY OF MINNESOTA

AI summary

Decentralized methods for computing optimal real and reactive power setpoints for residential photovoltaic (PV) inverters are described. Optimal power flow techniques are described that select which inverters will provide ancillary services and compute their optimal real and reactive power setpoints according to specified performance criteria and economic objectives.