An Improved Phase-Locked-Loop Control with Alternative Damping Factors for VSC Connected to Weak AC System

Table 1

Parameters of VSC connected to weak AC system.

	Parameter symbols	Value
Main circuit parameters	Equivalent AC source voltage	1.0 pu, 50 Hz
	Equivalent impedance of AC system	0.547 + 0.048 pu, impedance angle 85°
	Equivalent AC system SCR	1.83
	Rated DC power rating	1.0 pu
	PCC voltage	1.0 pu
	Converter impedance	0.003 + 0.15 pu
	Capacitor	0.15 pu
Controller parameters	Power controller gains (, )	(0.5, 50)
	AC voltage controller gains (, )	(0.35, 30)
	Inner controller gains (, )	(1, 10)
	Inner controller gains (, )	(1, 10)
	PLL gains (, )	(50, 10)