Delta Power Control Strategy for Multistring Grid-Connected PV Inverters

Ariya Sangwongwanich, Yongheng Yang*, Frede Blaabjerg, Dezso Sera

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

67 Citations (Scopus)
517 Downloads (Pure)


With a still increasing penetration level of grid-connected photovoltaic (PV) systems, more advanced active power control functionalities have been introduced in certain grid regulations. A delta power constraint, where a portion of the active power from the PV panels is reserved during operation, is required for grid support (e.g., during frequency deviation). In this paper, a cost-effective solution to realize delta power control (DPC) for grid-connected PV systems is presented, where the multistring PV inverter configuration is adopted. This control strategy is a combination of maximum power point tracking (MPPT) and constant power generation (CPG) modes. In this control scheme, one PV string operating in the MPPT mode estimates the available power, whereas the other PV strings regulate the total PV power by the CPG control strategy in such a way that the delta power constraint for the entire PV system is achieved. Simulations and experiments have been performed on a 3-kW single-phase grid-connected PV system. The results have confirmed the effectiveness of the proposed DPC strategy, where the power reserve according to the delta power constraint is achieved under several operating conditions.
Original languageEnglish
JournalIEEE Transactions on Industry Applications
Issue number4
Pages (from-to)3862 - 3870
Number of pages9
Publication statusPublished - Jul 2017


  • Active power control
  • Power reserve control
  • Maximum power point tracking (MPPT)
  • Constant power generation control
  • PV systems
  • Grid-connected power converters


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