Design of a robust PID-PSS for an uncertain power system with simplified stability conditions

Protection and Control of Modern Power Systems

Table 1 Relative stability and minimum damping ratio for x_e = 0.4 Ω with P and Q in p.u

Q	P = 0.2	P = 0.4	P = 0.6	P = 0.8	P = 1	P = 1.2
Relative Stability(σ_max)
−0.4	−0.5991	− 0.9047	− 1.2777	−1.2703	− 1.2601	− 1.2488
−0.2	− 1.2424	− 1.2948	−1.3183	− 1.3247	−1.3232	− 1.3177
0	−1.4383	− 1.3757	−1.3809	− 1.3872	−1.3888	− 1.3867
0.2	−1.8060	− 1.5422	−1.4889	− 1.4746	−1.4688	− 1.4642
0.4	− 2.3851	− 1.7942	− 1.6495	−1.5958	− 1.5709	−1.5566
Minimum damping ratio (ζ_min)
−0.4	0.3701	0.3517	0.3478	0.3461	0.3451	0.3438
−0.2	0.4627	0.3834	0.3610	0.3519	0.3473	0.3446
0	0.5465	0.4263	0.3843	0.3652	0.3550	0.3490
0.2	0.6119	0.4663	0.4100	0.3818	0.3659	0.3561
0.4	0.6643	0.4993	0.4338	0.3988	0.3780	0.3647