Modified Quasi-Steady State Model of DC System for Transient Stability Simulation under Asymmetric Faults

Table 2

The commutation process and the corresponding DC voltage instantaneous value for the single bridge inverter within one cycle.

Trigger pulse	Time period	Upper bridge valve state	Lower bridge valve state	Commutation state	DC voltage waveform	Corresponding relationship	DC voltage calculation
	~	Valve 3 commutes to 5	Valve 4 conducting	to		p-c, q-b, r-a
	~	Valve 5 conducting	Valve 4 conducting	—		p-c, r-a
	~	Valve 5 conducting	Valve 4 commutes to 6	to		p-b, q-a, r-c
	~	Valve 5 conducting	Valve 6 conducting	—		p-b, r-c
	~	Valve 5 commutes to 1	Valve 6 conducting	to		p-a, q-c, r-b
	~	Valve 1 conducting	Valve 6 conducting	—		p-a, r-b
	~	Valve 1 conducting	Valve 6 commutes to 2	to		p-c, q-b, r-a
	~	Valve 1 conducting	Valve 2 conducting	—		p-c, r-a
	~	Valve 1 commutes to 3	Valve 2 conducting	to		p-b, q-a, r-c
	~	Valve 3 conducting	Valve 2 conducting	—		p-b, r-c
	~	Valve 3 conducting	Valve 2 commutes to 4	to		p-a, q-c, r-b
	~	Valve 3 conducting	Valve 4 conducting	—		p-a, r-b

The expression of “” means a time period from time instant “” to the time instant “”.