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

Protection and Control of Modern Power Systems

Table 2 Relative stability and minimum damping ratio for x_e = 0.8 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	−1.1226	− 1.1529	− 1.1026	− 1.0545	− 1.0095	− 0.9677
−0.2	− 1.1544	−1.2014	− 1.1926	−1.1665	− 1.1344	−1.1007
0	−1.3007	−1.2934	− 1.2883	−1.2727	− 1.2499	−1.2233
0.2	−1.6075	−1.4763	− 1.4277	−1.3995	− 1.3744	−1.3488
0.4	− 2.0210	−1.7552	− 1.6261	− 1.5623	−1.5208	− 1.4877
Minimum damping ratio (ζ_min)
	P = 0.2	P = 0.4	P = 0.6	P = 0.8	P = 1	P = 1.2
−0.4	0.4378	0.4330	0.4285	0.4241	0.4196	0.4153
−0.2	0.5121	0.4497	0.4327	0.4246	0.4193	0.4150
0	0.5773	0.4931	0.4534	0.4353	0.4251	0.4184
0.2	0.5234	0.5384	0.4801	0.4515	0.4352	0.4248
0.4	0.4986	0.5725	0.5063	0.4690	0.4470	0.4329