Retrofittable fractionally-rated active grid dampening system and method for high distributed energy resources penetration grid

A method comprising:

• retrofitting a distribution or transmission transformer in distribution or transmission infrastructure with a retrofittable fractionally-rated active grid dampening system, by connecting terminals of the retrofittable fractionally-rated active grid dampening system in series to a secondary-side winding of the distribution or transmission transformer, wherein the retrofittable fractionally-rated active grid dampening system comprises:
• system terminals, including (i) a first input terminal, or a set thereof, and (ii) a second output terminal, or a set thereof, to couple in series to the secondary-side winding of the distribution or transmission transformer;
• a first stage fail-normal disconnection switch having a disconnection switch device that couples of the first input terminal, or the set thereof, of the system terminals;
• a second stage conversion and energy storage module coupled to the first stage fail-normal disconnection switch, the second stage conversion and energy storage module comprising a series converter and a shunt converter coupled to one or more energy storage equipment via a DC bus,
• a third stage transformer comprising a transformer having a first winding side and a second winding side, the first winding side coupled to outputs of the second stage conversion and energy storage module, and the second winding side coupled to the second output terminal or a set thereof;
• and
• a controller operatively coupled to the series converter and the shunt converter, the controller being configured, via computer readable instructions, to direct operation of the series converter and the shunt converter through the third stage transformer and the one or more energy storage equipment, as a network transient damper, to (i) control steady-state line power flow at the distribution or transmission transformer and (ii) provide dynamic shunt and series damping to grid transients at the distribution or transmission transformer.