Energy Storage Hedge Mode Plugin for Demand Charge Reduction
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Solution Overview
Problem
Conventional energy storage system controllers are unable to effectively manage average kW demand during power limited events, leading to unacceptably high demand charges due to insufficient time to discharge energy storage devices and maintain set-point levels, resulting in increased electricity costs for commercial and industrial customers.
Innovation Solution
A computer-implemented method that includes computing multiple discharge values during a pre-discharge phase and charge values during a compensatory charge phase of a utility measurement interval to optimize energy storage device operations, preemptively discharging and recharging to mitigate power limited events and reduce demand charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional system controllers discharge energy storage devices only when customer load is high, then the system operates simply and responds reactively, but the average kW demand cannot be effectively reduced during power limited events due to insufficient time remaining in the utility measure interval
Solution Approach 1:
The system performs preliminary discharge actions during the initial portion of the utility measure interval before the power limited event occurs. By proactively discharging the energy storage device in advance, the controller ensures that sufficient energy is available to counteract the anticipated high customer load, thereby maintaining average kW demand below the set-point despite the time constraint during the power limited event.
2Power
If the energy storage device discharges all stored electricity during a power limited event, then the immediate power demand is addressed, but the average kW demand for the entire utility measure interval exceeds the set-point due to insufficient time to discharge long enough
Solution Approach 1:
The controller calculates and executes a preliminary discharge strategy that releases a controlled amount of energy from the storage device during the initial portion of the utility measure interval. This pre-positioning of energy ensures that when the power limited event occurs, the average kW demand over the entire interval remains below the set-point, preventing excessive demand charges while still addressing the instantaneous power need.
Solution Approach 2:
The system dynamically adjusts the discharge rate and timing of the energy storage device based on real-time conditions including the customer load profile, remaining time in the utility measure interval, and the set-point requirements. This dynamic control allows the system to optimize the balance between instantaneous power delivery and average kW demand management, adapting the discharge strategy to the specific circumstances of each utility measure interval.
3Loss of energy
If the system waits to discharge energy storage devices until customer load is high, then energy is conserved during low-demand periods, but the system cannot respond effectively to power limited events with insufficient time remaining in the utility measure interval
Solution Approach 1:
The controller implements a preliminary discharge strategy that releases energy from the storage device during the initial portion of the utility measure interval when customer load may be lower. By proactively positioning energy in advance, the system ensures that sufficient discharge capacity is available to address power limited events, thereby maintaining both energy conservation during truly low-demand periods and effective demand management when needed.
Solution Approach 2:
The system continuously monitors customer load, energy storage device state-of-charge, and time remaining in the utility measure interval to dynamically adjust the discharge strategy. This feedback mechanism allows the controller to optimize the balance between energy conservation and demand management effectiveness, discharging energy preliminarily when it will be most beneficial for addressing anticipated power limited events while conserving energy when conditions permit.
Data Source
AI summary
In various embodiments, a hedge mode plugin increases the ability of an energy storage system to reduce the demand charges associated with purchasing electricity from a utility. A utility measurement interval (UMI) is divided into a pre-discharge phase and a subsequent compensatory charge phase. During the pre-discharge phase, the hedge mode plugin causes an energy storage device to discharge. At the beginning of the compensatory charge phase, the hedge mode plugin computes time-indexed charge values based on the total amount of energy that the energy storage device discharged during the pre-discharge phase. The hedge mode plugin then causes the energy storage device to charge based on at least one of the charge values. By systematically pre-discharging and re-charging the energy device, the hedge mode plugin optimizes the demand reduction effectiveness of the energy storage system during each UMI while stabilizing the state-of-charge of the energy storage device across multiple UMIs.