Power Dispatch Capacity of a Grid-Forming Control Based on Phase Restoring Principle

The concept of grid-forming control is driving system operators to define this technology's capabilities and requirements to maintain grid stability, reliability, and the need to provide some of the services previously provided by synchronous generators. The novel control strategy, called the “Phase Restoring Principle” (PRP), was recently introduced for converter operated power systems. This article provides further insights and confirmation of the PRP grid-forming capabilities based on the response requirements from the perspective of the power system. It describes the extension of the control by supplementing PRP with active power control allowing the control to cooperate with other sources. The generalized small-signal solution of the control is derived and evidenced. Analytical deductions supported by simulative evidence of the power dispatch based on PRP are displayed in single, double, and triple converter configurations. The development of steady-state operating point and, hence, drift frequency using the principle of PRP with active power control is examined and discussed based on reference values and weighted gain selection. The enhanced PRP control structure also displays controller stability for sufficiently small drift frequencies and achieves nominal frequency with dedicated parameters.