Modified Power-Based Control for Low Voltage Microgrid Inverters

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Solution Overview

Problem

Current technologies for controlling low voltage microgrids lack efficient methods for proportional sharing of active and reactive power, power unbalance compensation, and dynamic control responses without requiring detailed grid parameters or topology information, and cannot handle arbitrary inverter connections or operation in isolated modes.

Innovation Solution

A modified Power-Based Control (PBC) process that enables centralized communication for controlling low voltage microgrids, allowing proportional sharing of active and reactive power, power unbalance compensation, and operation with arbitrary inverter connections, without needing prior knowledge of grid parameters or topology, and supports multiple point of common coupling connections and isolated operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If traditional PBC methods are used for microgrid control, then implementation simplicity is maintained, but dynamic control response speed is insufficient and energy losses are higher

Engineering Contradiction:
Improvedynamic control response speedVSAvoidenergy losses
Core Design Contradiction:
SpeedVSLoss of energy

Solution Approach 1:

The patent modifies the traditional PBC algorithm by changing key control parameters including the introduction of a weighting factor alpha (α) that balances active and reactive power control, modification of power flow equations to account for arbitrary inverter connections, and adjustment of control cycle timing. These parameter changes enable faster dynamic response while reducing energy losses through optimized power distribution.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If detailed grid parameters and topology information are required for control, then control precision may be improved, but system complexity and implementation difficulty increase

Engineering Contradiction:
Improvecontrol implementation easeVSAvoidpower sharing precision
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The modified PBC algorithm enables the microgrid system to self-regulate power distribution without requiring external grid parameter information. Each inverter autonomously measures local voltage and current, calculates its own power contribution based on its capacity, and automatically adjusts its operation. This self-service approach eliminates the need for centralized grid topology knowledge while maintaining precise power sharing through distributed autonomous control.

Inventive Principle:
Principle #25Self-service

3Adaptability or versatility

If arbitrary inverter connections are allowed in the microgrid, then system flexibility and adaptability improve, but control complexity and difficulty of managing power unbalance increase

Engineering Contradiction:
Improveinverter connection flexibilityVSAvoidcontrol system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent develops a universal control algorithm that handles all types of inverter connections (phase-phase, phase-neutral, arbitrary combinations) through a single unified mathematical framework. The modified PBC equations universally accommodate any connection topology by using generalised power flow relationships that do not depend on specific connection configurations. This universal approach manages control complexity while maintaining maximum flexibility for arbitrary inverter connections.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Adaptability or versatility

If multiple PCCs and isolated operation modes are supported, then microgrid versatility improves, but control system complexity and coordination difficulty increase

Engineering Contradiction:
Improveoperation mode flexibilityVSAvoidcontrol coordination complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The control algorithm dynamically adapts to different operational modes (grid-connected with multiple PCCs, islanded mode, hybrid modes) by continuously monitoring system state and adjusting control parameters in real-time. The modified PBC equations incorporate dynamic switching mechanisms that automatically reconfigure power flow paths and control strategies based on the current operational mode, enabling versatile operation without requiring complex manual reconfiguration or multiple dedicated control systems.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS20240120746A1Process for controlling low voltage microgrids
Publication Date: 2024.04.11 PETROLEO BRASILEIRO SA PETROBRAS

AI summary

This technology is a process for controlling low voltage microgrids (MGs) with centralized communication, based on the “Power-Based Control” (PBC) technique adapting the same to a modified PBC (MPBC) process. The technology provides the following technical effects: 1) sharing of active power and reactive power proportionally to the capacity of distributed energy resources (DERs) of the MG; 2) power unbalance compensation at the point of common coupling (PCC or PAC in Portuguese); 3) the process can be implemented without knowing the parameters and topology of the power grid; 4) ability to handle the arbitrary connection of inverters in the MG; 5) it makes possible to distinguish between DERs connected to the MG in both types of connection: phase-phase and phase-neutral, wherein single-phase DERs connected arbitrarily between the phases share the amounts of balanced power, while the unbalanced and homopolar powers are steered only to the inverters connected between phase and neutral; 6) it allows the connection of the MG to multiple PCCs and also the operation in isolated mode (“islanded”). The technology is applied in the technical field of equipment and infrastructure for the development of MGs.