SoC-Adaptive Droop Control for Grid-Storage Power Flow
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Solution Overview
Problem
Power systems connected to an electrical grid face limitations in controlling input and output power due to finite energy storage capacity, leading to potential failures when instructed to adjust energy levels beyond their storage capacity, especially when the State of Charge (SoC) is low or high, affecting grid frequency stabilization.
Innovation Solution
A control apparatus that adjusts the drooping characteristics of input and output power based on the State of Charge (SoC) of the power storage, determining the output destination and rate to autonomously manage energy flow, preventing failures by strategically adjusting energy input and output according to the SoC levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power adjustment control is applied to power systems with limited storage capacity, then grid frequency stabilization is improved, but system reliability deteriorates due to potential failures when energy adjustment exceeds storage capacity
Solution Approach 1:
The control method dynamically adjusts the drooping characteristics (slope of power-frequency relationship) based on the state of charge (SoC) of the power storage. When SoC is high, the drooping slope is increased to prioritize discharge; when SoC is low, the slope is decreased to prioritize charging, preventing the system from attempting adjustments beyond storage capacity while maintaining grid frequency stabilization
Solution Approach 2:
The invention changes the control parameter (drooping characteristics slope) according to the SoC level. By modifying this parameter based on storage state, the system adapts its energy adjustment capability to match available storage capacity, resolving the contradiction between maintaining adaptability and ensuring reliability
2Productivity
If power adjustment instructions are executed without considering SoC limits, then grid demand accommodation is improved, but power system stability deteriorates due to charging/discharging failures
Solution Approach 1:
The control method continuously monitors the state of charge (SoC) of the power storage and uses this feedback to adjust the drooping characteristics in real-time. This closed-loop control ensures that power adjustment instructions are executed within the bounds of available storage capacity, preventing failures while maintaining productivity
Solution Approach 2:
The system preliminarily determines the appropriate drooping characteristics before executing power adjustment instructions, based on the current SoC level. This preliminary adjustment of control parameters prevents attempts to charge or discharge beyond capacity limits, ensuring stability while maintaining adjustment capability
Data Source
AI summary
A control apparatus controlling a power output apparatus that generates, based on input power from one of an electrical grid and a power storage, output power to another of the electrical grid and the power storage is provided. The control apparatus includes: a communicator to receive a grid frequency of the electrical grid and a state of charge of the power storage, or information allowing the grid frequency and the state of charge to be calculated; and a processor to determine an output destination and an output rate of the output power, based on a function of calculating the output destination and the output rate according to the grid frequency. The output destination and the output rate are adjusted according to the state of charge, by the processor changing, according to the state of charge, the function used to determine the output destination and the output rate.