Microgrid Voltage Control via Reactive Power Coordination
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Solution Overview
Problem
Microgrids with high renewable energy penetration face voltage rise and collapse issues due to intermittent energy sources like PV and wind, especially in islanded modes, where traditional fossil-fuel generators are insufficient and costly, and lack reactive power support.
Innovation Solution
A computer-implemented method and system using a resiliency controller with Model Predictive Control (MPC) to distribute reactive power and droop-based controllers to guide distributed generators (DGs) for voltage regulation, predicting future system behavior and optimizing reactive power distribution to maximize renewable energy usage and minimize fossil-fuel generator usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If renewable energy sources (PV and wind) are used to replace fossil-fuel generators, then emission and fuel cost are reduced, but reactive power support becomes insufficient and voltage control reliability deteriorates
Solution Approach 1:
The invention segments the reactive power control into two levels: a central controller that performs model predictive control to determine optimal reactive power distribution, and local DG controllers that execute droop control. This segmentation allows renewable DGs to provide reactive power support without requiring fossil-fuel generators, resolving the contradiction between reducing harmful emissions and maintaining reliability.
Solution Approach 2:
The invention implements feedback mechanisms where the central controller continuously monitors voltage measurements from multiple buses and adjusts reactive power distribution accordingly. The droop control at local level also provides feedback by adjusting reactive power output based on voltage deviations. This feedback ensures reliable voltage control while using only renewable energy sources.
2Reliability
If diesel generators are used to provide reactive power support, then voltage control reliability is improved, but fuel cost and emission increase
Solution Approach 1:
The invention extracts the reactive power support function from fossil-fuel generators and assigns it to renewable DGs equipped with power electronic converters. By taking out this function and assigning it to renewable sources with intelligent control, the system achieves reliable voltage control without incurring fuel cost and emission penalties.
Solution Approach 2:
The invention replaces the mechanical system of diesel generators with an electronic control system. The model predictive control and droop control use electronic measurements and calculations to manage reactive power from renewable DGs, substituting mechanical fossil-fuel-based generation with electronic control of renewable sources, thereby eliminating fuel cost and emission while maintaining voltage control reliability.
3Device complexity
If reactive power is not compensated in islanded microgrids, then system complexity is reduced, but voltage fluctuations increase and secure operation becomes difficult
Solution Approach 1:
The invention enables the microgrid to self-regulate voltage through distributed reactive power compensation. Each DG unit autonomously adjusts its reactive power output based on voltage measurements and control signals, allowing the system to maintain secure operation without external reactive power compensation equipment. This self-service approach maintains reliability while avoiding the complexity of additional compensation devices.
Data Source
AI summary
A computer-implemented method for controlling voltage fluctuations of a microgrid including a plurality of distributed generators (DGs) is presented. The computer-implemented method includes collecting, by a resiliency controller, measurement data from the microgrid, using a model predictive control (MPC) module to distribute reactive power to each of the DGs of the microgrid, and using a droop based controller to guide operation of each of the DGs of the microgrid.