Selfish Herd Optimisation tuned fractional order cascaded controllers for AGC Analysis

Abstract

This article deals with automatic generation control (AGC) of a three-area power system having five diversified sources of generation like thermal unit, hydro unit, wind unit, diesel unit and a gas unit are interconnected together. Area-1 of the power system consists of a thermal, a hydro and a wind unit, area-2 has a thermal, a hydro and a diesel unit and area-3 consists of a thermal, a hydro and a gas unit. To make system more realistic different nonlinear components like governor dead band (GDB), generation rate constraint (GRC), boiler dynamics and communication delay are taken into account. A novel two-degree of freedom fractional order PID with derivative filter and fractional order PD with derivative filter (2-DOF-FOPIDN-FOPDN) cascaded control strategy is adopted to improve the dynamic performance of the power system. The results obtained with the proposed cascaded controller are compared with that of PID, FOPID and 2-DOF-PIDN-PDN cascaded controller to prove its superiority. To enumerate the gains of different controllers optimally, a recently developed bio-inspired optimisation algorithm named selfish herd optimisation (SHO) is capitalised. Further, the work is extended by taking a two-area hydro-thermal system to compare the result of the SHO tuned PID controller with that of modern hybrid firefly algorithm-pattern search (hFA-PS) technique. Transient analysis is carried out by applying a sudden load disturbance of 0.01 p.u in area-1 and the robustness of the controller is examined by varying both system parameters and applying a randomly varying load in area-1. From the investigation it is concluded that the 2-DOF-FOPIDN-FOPDN controller gives a flawless and a distinct performance.

Appendices

Appendix A

$K_{ps} = 120,\,T_{ps} = 20s,\,R_{x} = R_{y} = R_{z} = 2.4,\,B_{1} = B_{2} = B_{3} = 0.425,\,T_{12} = T_{23} = T_{31} = 0.0707,\,a_{12} = a_{13} = a_{23} = - 1.$

Thermal Units:

$T_{g1} = 0.2\,s$, $T_{t} = 0.3\,s$, $T_{r} = 10\,s$, $K_{r} = 0.333\,$, $N_{1} = 0.8$, $N_{2} = - 0.2$, $K_{1} = 0.85$, $K_{2} = 0.095$, $K_{3} = 0.92$, $c_{B} = 200$, $K_{ib} = 0.5$, $T_{ib} = 26\,s$, $T_{rb} = 69\,s$, $T_{D} = 0$, $T_{F} = 10\,s$, $T_{t} = 0.3\,s$.

Hydro Units:

$T_{g2} = 48.7\,s$, $T_{1} = 0.513\,s$, $T_{2} = 10\,s$, $T_{w} = 1s$.

Gas Unit:

$C_{GS} = 1$, $B_{GS} = 0.05$, $X_{GS} = 0.6$, $Y_{GS} = 1$, $T_{CR} = 0.01\,s$, $T_{FR} = 0.23\,s$, $T_{CD} = 0.2\,s$.

Wind Farm & Diesel Unit:

$k_{2} = 1.25$, $k_{3} = 1.4$, $T_{p1} = 0.6\,s$, $T_{p2} = 0.041\,s$, $k_{diesel} = 16.5\,$.

Appendix B

$K_{ps} = 120$, $T_{ps} = 20s$, $B_{1} = B_{2} = 0.425$, $R_{1} = 2$, $R_{2} = 2.4$, $T_{12} = 0.0707$, $a_{12} = - 1$.

Thermal Units:

$T_{g} = 0.08\,s$, $T_{t} = 0.3\,s$.

Hydro Units:

$T_{g} = 48.7\,s$, $T_{H1} = 0.513\,s$, $T_{H2} = 10\,s$, $T_{w} = 1s$.