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Method for Photovoltaic Maximum Power Point Estimation

National Renewable Energy Laboratory

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Technology Marketing Summary

With the increased penetration of connected photovoltaic (PV) power systems in large-scale transmission grids and in consumer-scale distribution grids, the conventional rotating machines that have supplied rotational inertia and primary frequency regulation (PFR) on fast time scales are being displaced. The displacement of these conventional rotating machines threatens grid stability due to the time-intermittent outputs of PV plants.

The best way to mitigate the effects of PV energy generators on the grid is to supply PFR, synthetic inertia, or fast frequency response from these systems through operating PV plants below their maximum power point. This is advantageous because operating PV plants below their maximum power point will ultimately create a power reserve margin that can be automatically dispatched during frequency transients. The existing methods for Maximum Power Point Estimation (MPPE) are either performed offline, where there is a need for regression analysis and neural networks, or in real time, where assumptions must be made. While these methods are useful, they require large amounts of data or are relatively inaccurate. Therefore, a better method for the estimation of a PV systems’ maximum available output is needed.

Description

NREL scientists have invented a novel method for estimating the maximum available output from a PV system from measured solar irradiance and PV array temperature. This method, while only using the limited processing power typically available in PV inverter embedded controls, is the first known method that combines accuracy with low processing requirements. Additionally, this method ensures there is sufficient power reserve in real time while providing PFR from PV systems without requiring energy storage by operating below maximum power.

Benefits
  • Accurate
  • Can be performed in the inverter
  • Enables various methods of PV active power control
  • Enables emulation of inertial response of conventional generators
  • Compatible with any PV module, requiring only typical module data sheet values
  • Effective over the full range of temperature and irradiance conditions that may be seen in the field
Applications and Industries
  • Photovoltaic Systems
  • PV Maximum Power Point Tracking Methods
  • Power System Frequency Support
  • Grid Stability
  • Active Power Control of PV Systems
More Information

For more information, read this 2015 IEEE article, Real-time photovoltaic plant maximum power point estimation for use in grid frequency stabilization.

Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
ROI 16-06ProposedAvailable08/12/201608/12/2016

Contact NREL About This Technology

To: Erin Beaumont<erin.beaumont@nrel.gov>