Solar Output Smoothing Using Forecast-Guided Energy Storage
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Solution Overview
Problem
The intermittency of solar resource availability poses challenges for electric grids, as existing methods require large and costly energy storage systems to smooth the output of solar energy systems, making them economically impractical.
Innovation Solution
A method that uses short-term solar resource forecasting to calculate a smoothed energy target-value for a solar energy system comprising a photovoltaic array, inverter, and energy storage device, allowing for efficient energy delivery and storage management within a small energy storage capacity, such as less than 0.1 times the photovoltaic array's output rating, to reduce variance during intermittency periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large energy storage systems are used to smooth solar output, then the variance in energy delivery is reduced, but the system cost increases significantly
Solution Approach 1:
The system performs preliminary action by acquiring irradiance forecasts for future time periods and using them to proactively adjust energy storage charging/discharging decisions before intermittency events occur. This allows the system to prepare for expected solar output variations and smooth delivery without requiring oversized storage capacity.
Solution Approach 2:
The system implements feedback by continuously monitoring actual irradiance data from past time periods, comparing it with forecasted data, and adjusting the smoothed energy target-value dynamically. This closed-loop control enables the system to respond to real-time conditions and maintain smooth energy delivery with minimal storage capacity.
2Ease of manufacture
If energy storage capacity is reduced to lower costs, then the economic viability improves, but the ability to smooth output during intermittency deteriorates
Solution Approach 1:
By acquiring irradiance forecasts for future time periods in advance, the system can proactively plan energy storage operations to smooth output variations. This preliminary action allows small storage systems to achieve smoothing效果 that would otherwise require much larger storage capacity, improving economic viability.
Solution Approach 2:
The system changes the operational parameters of the energy storage device dynamically by adjusting charging and discharging rates based on forecasted irradiance conditions. This allows the storage system to operate more efficiently and achieve better smoothing performance from a smaller capacity, reducing overall system cost.
3Reliability
If short-term forecasting is implemented, then the energy delivery smoothness is improved with smaller storage, but the system complexity increases
Solution Approach 1:
The system segments the time horizon into distinct past, present, and future time periods, with different data acquisition and processing strategies for each. This segmentation allows the system to manage complexity by handling forecasting and control decisions in discrete, manageable time steps rather than as a continuous complex problem.
Solution Approach 2:
The system introduces an intermediary smoothed energy target-value that mediates between actual solar output and delivered energy. This intermediary parameter simplifies the control problem by providing a clear target for the energy storage system to achieve, reducing the complexity of direct control while maintaining smooth delivery.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the variance in energy delivery, achieving a smoothed output curve with a smaller energy storage system, thereby improving the economic viability of solar energy systems by incorporating short-term irradiance forecasts to manage energy storage and delivery effectively.
Implementation Method 1
a solar energy system comprising a photovoltaic array, an inverter, and an energy storage device
Data Source
AI summary
A solar energy system comprising a photovoltaic array, an inverter, and an energy storage device is operated according to the following steps: (a) accessing irradiance data for a past time period; (b) acquiring an irradiance forecast for a future time period having a length of not more than 15 minutes and having a cumulative irradiance forecast of between 20% and 80% of clear-sky irradiance; (c) calculating a smoothed energy target-value for an imminent time step within the future time period, using the irradiance data for the past time period and the forecasted irradiance for the future time period; and (d) during the time step, delivering a quantity of energy to the inverter based on the calculated smoothed energy target-value. The energy storage device stores energy when more is produced than delivered, and discharges energy when more is delivered than is produced.