AC-Coupled Renewable Storage for Firm Grid Power Delivery
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Solution Overview
Problem
Conventional renewable energy systems face challenges in providing stable and predictable power due to intermittent energy sources like solar and wind, leading to network frequency and voltage deviations, and require costly infrastructure upgrades to handle peak demand, while also underutilizing existing transmission resources.
Innovation Solution
An integrated renewable energy source and energy storage system (RES-ESS) facility is configured to supply aggregated power to an AC grid, with oversized inverters and energy storage capacity to emulate a baseload power station, using time-dependent forecasts and state of charge schedules to manage power delivery and avoid exceeding grid interconnection limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If renewable energy resources replace traditional fossil-fired baseload power plants, then environmental sustainability is improved, but transmission infrastructure utilization is reduced and new infrastructure costs increase
Solution Approach 1:
The energy storage device stores excess renewable energy generated during peak production periods (when solar is strongest or wind is highest) before transmission capacity is needed, enabling the system to deliver stable power during peak demand periods without requiring upgraded transmission infrastructure
Solution Approach 2:
The system changes the temporal distribution parameter of energy delivery by storing energy when generation exceeds demand and releasing it when demand exceeds generation, transforming intermittent renewable output into stable baseload-equivalent delivery while maintaining full utilization of existing transmission capacity
2Reliability
If renewable energy resources are increased to provide greater percentage of electrical supply, then environmental sustainability is improved, but grid stability deteriorates due to intermittent nature and rapid fluctuation
Solution Approach 1:
The control system continuously monitors the state of charge of the energy storage device and the output of renewable energy resources, dynamically adjusting charge/discharge operations to smooth fluctuations and maintain stable power delivery to the grid, with the feedback loop responding to real-time conditions
Solution Approach 2:
The energy storage device acts as a cushion by absorbing rapid fluctuations and variability in renewable energy output before they reach the grid, preventing stability issues while allowing high penetration of renewable resources
3Productivity
If conventional renewable energy systems operate at low capacity factors, then resource availability is maintained, but transmission infrastructure underutilization increases
Solution Approach 1:
The energy storage device enables continuous useful action by storing excess renewable energy during periods of high generation and delivering it during periods of high demand, maintaining continuous power delivery and maximizing utilization of transmission infrastructure throughout all hours of the day
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 configuration enables high capacity factors and stable power delivery, reducing the need for costly infrastructure upgrades and enhancing grid stability by providing a fixed firm capacity for extended durations, thus addressing the limitations of conventional renewable energy systems.
Implementation Method 1
A renewable energy source (RES), such as a photovoltaic (PV) array
Implementation Method 2
a battery energy storage system or BESS
Data Source
Figure 1
Figure 2~3
Figure 4A
AI summary
An integrated renewable energy source (RES) and energy storage system (ESS) facility configured to supply power to an AC electric grid includes energy storage system capacity and inverter capacity that are larger than a point of grid interconnect (POGI) limit for the facility, enabling high capacity factors and production profiles that match a desired load. At least one first DC-AC power inverter is associated with RES, and at least one second AC-DC power inverter is associated with the ESS. AC-DC conversion is used when charging the ESS with RES AC electric power, and DC-AC conversion utility is used when discharging ESS AC electric power to the electric grid. Aggregate DC-AC inverter utility exceeds the facility POGI limit, and excess RES AC electric power may be diverted to the second inverter(s).