Recommendation of equipping steam unit of khoy combined cycle power plant with novel PID-PSS2B industrial stabilizer to decrease risk of sudden trips

In order to acquire a more stable power unit, it is invaluable to find methods of enhancing plant stability. The position of Khoy combined cycle power plant (CCPP) is strategic from aspects of contribution in providing power for some important local and regional substations in proximity of Turkey. Current steam unit lacks any supplementary stabilizer and trips frequently following of various small and large perturbations. Hence, it seems to be essential to equip the unit with a good-structure industrial power system stabilizer (PSS) such as PSS2B to decrease risk of emergency outages. Nowadays in all over the world, new advanced industrial excitation control systems use IEEE Std. 421.5 to build practical stabilizer of PSS2B from the accelerating power signal to cover a wide range of oscillation frequencies. PSS2B module can be utilized as an add-on to retrofit excitation systems in refurbishment programs. The robust coordinated design of proportional-integral-derivative (PID) based PSS2B and PID-automatic voltage control (AVR) of the steam unit is formulated as a nonlinear optimization problem in which adjustable parameters are optimized simultaneously via an improved particle swarm optimization (IPSO) algorithm by minimizing integral of time multiplied squared error (ITSE) performance index. Siemens RG3 excitation system is modeled according to IEEE AC7B. To evaluate the robustness and effectiveness of recommended stabilizer, eigenvalue analysis and dynamic simulations are performed in MATLAB/SIMULINK for different operating conditions and disturbances. The results show that proposed stabilizer can provide outstanding enhancement in dynamic stability for steam unit to reduce its emergency outages.