Supervisory Controller for PV Ramp Rate Management
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Solution Overview
Problem
Existing PV systems struggle to control power ramp rates effectively, leading to inefficiencies in capturing solar energy and increased energy costs, as they often exceed maximum prescribed ramp rates, which are difficult for thermal power plants to match due to rapid solar irradiation changes.
Innovation Solution
A supervisory PV system controller manages collective power ramp rates across multiple PV subsystems by communicating ramp rate change limiting signals, using a combination of power sensors, adaptive controllers, and closed-loop feedback systems to ensure ramp rates align with transmission system operator specifications, allowing for optimal energy capture while adhering to prescribed limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PV systems operate at maximum power output to capture all solar energy, then energy capture is maximized, but power ramp rates exceed maximum prescribed limits causing grid instability
Solution Approach 1:
The system dynamically adjusts the power output of individual PV subsystems based on real-time solar irradiation conditions and aggregate ramp rate requirements. Each subsystem's power level is made variable and adaptive, transitioning from static maximum power point tracking to dynamic control that responds to changing environmental conditions and system-wide constraints.
Solution Approach 2:
The controller implements closed-loop feedback by continuously monitoring solar irradiation levels, calculating expected power changes, comparing actual aggregate ramp rates against prescribed limits, and adjusting individual subsystem power levels accordingly. This feedback mechanism enables the system to self-correct and maintain compliance with ramp rate constraints while maximizing energy capture.
2Reliability
If PV systems limit power output to control ramp rates within prescribed limits, then grid stability is maintained, but solar energy capture is reduced and energy costs increase
Solution Approach 1:
The PV system is divided into multiple independently controllable subsystems, each equipped with its own power sensor and control mechanism. This segmentation allows the controller to selectively adjust power levels in specific subsystems based on local solar irradiation conditions, enabling fine-grained control that minimizes overall energy loss while maintaining ramp rate compliance.
Solution Approach 2:
The system changes the operating parameters of individual PV subsystems dynamically, adjusting power output levels based on real-time solar irradiation measurements and system-wide ramp rate requirements. This parameter adjustment enables the system to operate at or near maximum power when conditions permit, while automatically reducing output only when necessary to meet ramp rate constraints.
3Reliability
If thermal power plants adjust output to balance PV variability, then overall power stability is maintained, but response time is insufficient due to slow ramping capabilities
Solution Approach 1:
The system performs preliminary actions by proactively monitoring solar irradiation conditions and predicting upcoming power changes before they occur. By calculating expected power variations based on irradiation rate of change and applying predictive control algorithms, the system adjusts PV subsystem output in advance to prevent excessive ramp rates, eliminating the need for reactive thermal power plant adjustments.
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 enables coordinated control of PV system output power ramp rates, maximizing solar energy capture while maintaining ramp rates within operator-specified limits, thereby improving the integration of PV systems with the grid and reducing energy costs.
Implementation Method 1
Photovoltaic cells generate direct current (DC) power with the level of DC current being dependent on solar irradiation
Data Source
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AI summary
A photovoltaic (PV) control system (40) generates a power output rate control signal based on a monitored rate of change of collective power output generated via a plurality of PV subsystems (42) and a desired collective output power change rate for the plurality of PV subsystems (42) and communicates the power output rate control signal to the plurality of PV subsystems (42) to control a rate of change of one or more operating parameters of individual PV subsystems in order to control a rate of change of collective output power of the plurality of solar PV subsystems (42).