Research on Discretization PI Control Technology of Single-Phase Grid-Connected Inverter with LCL Filter

Table 2

The unstable region under different parameters.

	Unstable region 1/Hz		Unstable region 2/Hz		Unstable region 3/Hz		Unstable region 4/Hz
	Upper	Lower	Upper	Lower	Upper	Lower	Upper	Lower
1st	6600	3450	2175	1720	1310	1140	940	855
2nd	6600	3500	2175	1750	1310	1160	940	855
3rd	6600	3350	2175	1680	1310	1120	940	840
4th	6600	3450	2175	1720	1310	1140	940	855
5th	6600	3500	2175	1750	1310	1160	940	855
6th	6600	3350	2175	1680	1310	1120	940	840
	2/1	2/2	2/3	2/4	2/5	2/6	2/7	2/8