Battery Frequency Response Control with Variable State-of-Charge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Determining optimal adjustments for battery storage controllers to participate in frequency response programs while managing energy and demand charges is challenging, as existing systems struggle to balance revenue generation and battery degradation costs.
Innovation Solution
A frequency response optimization system that includes a battery, a power inverter, and a frequency response controller, which receives regulation signals, determines optimal battery power setpoints, and manages state-of-charge to maximize revenue while minimizing degradation, using high and low-level controllers and battery life models to filter signals and constrain objectives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the battery storage controller actively participates in frequency response programs by adjusting load in response to regulation signals, then frequency response revenue is generated, but battery degradation increases and energy costs rise
Solution Approach 1:
The system performs preliminary actions by determining an optimal frequency response midpoint at the beginning of the frequency response period that anticipates future regulation signals and battery state changes. This advance planning allows the controller to prepare optimal battery power setpoints that balance revenue generation with battery preservation, rather than reacting impulsively to each regulation signal which would accelerate degradation
Solution Approach 2:
The system dynamically adjusts the frequency response midpoint and battery power setpoints based on real-time regulation signal statistics and battery state-of-charge conditions. The controller continuously monitors the regulation signal, determines its statistics, and adapts the midpoint and power setpoints throughout the frequency response period to optimize the trade-off between revenue generation and battery degradation in response to changing conditions
2Adaptability or versatility
If the battery storage controller adjusts load in response to regulation signals, then frequency response participation is achieved, but difficulty in determining optimal midpoint adjustment increases
Solution Approach 1:
The system implements feedback by continuously monitoring the regulation signal and determining its statistics, then using this information to adjust the frequency response midpoint and battery power setpoints. The controller receives feedback from the battery state-of-charge and regulation signal performance, and uses this feedback to optimize future control actions, creating a closed-loop system that simplifies the complexity of determining optimal midpoint adjustments
Solution Approach 2:
The frequency response midpoint acts as an intermediary variable that mediates between the regulation signal inputs and the battery power output. Rather than directly controlling battery power based on raw regulation signals, the system uses the midpoint as an intermediate parameter that absorbs and smooths the complexity of signal processing, making the control system more manageable and adaptable
Data Source
AI summary
A frequency response optimization system includes a battery configured to store and discharge electric power, a power inverter configured to control an amount of the electric power stored or discharged from the battery at each of a plurality of time steps during a frequency response period, and a frequency response controller. The frequency response controller is configured to receive a regulation signal from an incentive provider, determine statistics of the regulation signal, use the statistics of the regulation signal to generate an optimal frequency response midpoint that achieves a desired change in a state-of-charge (SOC) of the battery while participating in a frequency response program, and use the midpoints to determine optimal battery power setpoints for the power inverter. The power inverter is configured to use the optimal battery power setpoints to control the amount of the electric power stored or discharged from the battery.