No abstract

Summary The penetration of large‐scale photovoltaic farms (LPFs) is ever increasing. Given that LPFs are added to power systems or replaced by conventional power plants, they should undertake the most common tasks of synchronous generators. One of these tasks is the low‐frequency oscillation (LFO) damping using power system stabilizer. This paper proposes a general method for LFO damping using LPFs by designing an optimal proportional‐integral‐derivative (PID) controller as a power oscillation damper in the nonlinear control loop of LPF. Considering the need for a valid LPF model, therefore the second generation generic model, developed and approved by western electricity coordinating council, is used. The PID controller is optimally tuned using the particle swarm optimization algorithm in order to produce an effective LFO damping. Finally, the performance of this controller is investigated in the modified two‐area test system, showing the proper performance of the LPF for LFO damping using the proposed optimal PID controller in the various operating condition and different short circuit ratio values.

The penetration of inverter-based power plants (IBPPs), such as large-scale photovoltaic (PV) power plants (LPPPs), is ever increasing considering the merits of renewable energy power plants (REPPs). Given that IBPPs are added to power systems or replaced by conventional power plants, they should undertake the most common tasks of synchronous generators. The low-frequency oscillation (LFO) damping through the power system stabilizers (PSSs) of synchronous generators is regarded as one of the common tasks in power plants. This paper proposes an optimal fractional-order proportional-integral-derivative (FOPID) controller implemented in the control loop of IBPPs for LFO damping in power systems. For this purpose, the last version of the generic dynamic model for renewable technologies (GDMRT) is used, which was released by the Western Electricity Coordinating Council (WECC) and Electric Power Research Institute (EPRI). In addition, an LPPP is studied as a case study. The FOPID controller is optimally tuned using the particle swarm optimization (PSO) algorithm in order to produce effective LFO damping. Finally, the performance of this controller is simulated and investigated in a two-area test system, showing the better performance of the LPPP for LFO damping by using the proposed optimal FOPID controller compared to the optimal lead-lag controller and optimal PID controller.

Summary In recent years, the installation of large‐scale photovoltaic (PV) farms (LPFs) is expanding around the world. Due to the addition of LPFs to the power system and increasing their penetration level, they should be able to undertake the most common tasks of conventional power plants in coordinated with other devices in the power system. Damping of low‐frequency oscillation (LFO) through the power system stabilizers (PSSs) is regarded as one of these common tasks. Therefore, the LPF must be able to damp the LFO in coordinated with the PSSs. This paper proposes a new method for LFO damping in power system which is based on optimal coordination of wide‐area measurement‐based fractional‐order proportional‐integral‐derivative (WMFOPID) controller as an auxiliary controller for LPF and PSSs of synchronous generators. The performance evaluation of the optimal coordinated WMFOPID controller is performed in a smart two‐area power system and is compared with other controllers in terms of LFO damping. The simulation results show the better performance of the optimal coordinated WMFOPID controller compared to the uncoordinated case and determine the effectiveness of the novel proposed method for LFO damping. The results also show the high robustness of the optimal WMFOPID controller compared to previous controllers, against some uncertainties in the power system.

The objective of present work is to apply the friction stir processing (FSP) to fabricate functionally graded SiC particulate reinforced Al6061 composite and investigate the effect of SiC particle mass fraction distribution on the mechanical properties and wear behavior of Al6061/SiC composite. Regarding the obtained results in this work, with increasing SiC mass fraction, elongation decreased, but hardness enhanced. However, the optimized functionally graded composite with the highest tensile strength and wear resistance was achieved for composite with 10 wt% surface SiC. Also, the results showed that wear resistance and tensile strength decreased for composite with 13 wt% surface SiC, due to reinforcement particle clustering depending on high SiC mass fraction.