Microgrid Controller Load Sharing Between Generators and Batteries
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Solution Overview
Problem
Islanded microgrids face challenges in frequency control due to imbalances between renewable energy generation and load demand, exacerbated by low inertia and small time constants, necessitating effective load sharing between isochronous generators and battery energy storage systems.
Innovation Solution
A power distribution system with a controller that determines optimal load balance using microgrid optimization modules, calculates frequency set points for energy storage resources, and controls frequency to achieve load balance by communicating schedules and settings between generation assets and energy storage systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery energy storage systems are used for power balancing in islanded microgrids, then frequency control and power quality are improved, but device complexity and control difficulty increase
Solution Approach 1:
The patent introduces a microgrid controller as an intermediary device that coordinates between isochronous generators and battery energy storage systems. The controller calculates frequency setpoints for batteries based on system frequency deviations and generator outputs, enabling automated load sharing without requiring complex direct coordination between distributed resources. This mediator approach simplifies the overall control architecture while maintaining reliable frequency control.
Solution Approach 2:
The patent implements dynamic frequency setpoint adjustment for battery energy storage systems based on real-time system frequency and generator output conditions. The controller continuously calculates optimal battery frequency setpoints using the formula: f_setpoint = f_system + K*(P_generator - P_load), where K is a control coefficient. This dynamic adaptation allows the system to respond to changing load and generation conditions, improving frequency control reliability while keeping control logic manageable through a systematic approach.
2Reliability
If load sharing is implemented between isochronous generators and battery energy storage systems, then power imbalances are reduced, but measurement precision and control accuracy requirements increase
Solution Approach 1:
The patent implements a feedback mechanism where the microgrid controller continuously monitors system frequency and generator outputs, then uses this information to calculate and adjust battery frequency setpoints. The controller measures actual system frequency deviations and generator power outputs, feeds this information back into the control algorithm, and adjusts battery setpoints accordingly. This closed-loop feedback approach enables accurate load sharing by compensating for measurement uncertainties and maintaining precise power balancing despite varying operating conditions.
Data Source
AI summary
Embodiments provide for controlling power production in an islanded microgrid system while maintaining the system frequency and implementing desired load sharing between different types of generating resources and energy storage systems. Embodiments include a controller in communication with the resources to control operation of the resources and operative to determine an optimal load balance based on load and renewable generation forecast information; transmit load and generation schedules to a generation controller that operates the resources in accordance with the schedules; calculate a frequency set point for energy storage resources in the microgrid based on the optimal load balance of the energy storage resources, droop settings, rated power, and the frequency of the energy storage resources; and to control the frequency set point of the energy storage resources to achieve the optimal load balance. Numerous additional aspects are disclosed.