Fuzzy Logic Controller for Low Voltage Ride Through Capability Improvement of Grid Connected Photovoltaic Power Plants

Author(s):  
Prakash A. Banu ◽  
Devaraju T. ◽  
◽  
Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4461
Author(s):  
Ahsanullah Memon ◽  
Mohd Wazir Mustafa ◽  
Muhammad Naveed Aman ◽  
Mukhtar Ullah ◽  
Tariq Kamal ◽  
...  

Brushless doubly-fed induction generators have higher reliability, making them an attractive choice for not only offshore applications but also for remote locations. These machines are composed of two back-to-back voltage source converters: the grid side converter and the rotor side converter. The rotor side converter is typically used for reactive current control of the power winding using the control winding current. A low voltage ride through (LVRT) fault is detected using a hysterisis comparison of the power winding voltage. This approach leads to two problems, firstly, the use of only voltage to detect faults results in erroneous or slow response, and secondly, sub-optimal control of voltage drop because of static reference values for reactive current compensation. This paper solves these problems by using an analytical model of the voltage drop caused by a short circuit. Moreover, using a fuzzy logic controller, the proposed technique employs the voltage frequency in addition to the power winding voltage magnitude to detect LVRT conditions. The analytical model helps in reducing the power winding voltage drop while the fuzzy logic controller leads to better and faster detection of faults, leading to an overall faster response of the system. Simulations in Matlab/Simulink show that the proposed technique can reduce the voltage drop by up to 0.12 p.u. and result in significantly lower transients in the power winding voltage as compared to existing techniques.


In recent years, due to the interconnection of large capacity wind turbines to the power grid lead, there are serious issues in the stability of Grid and generation of electrical power. Also, it is showing effect on the dynamic performance of the electrical power systems. To maintain stability during sudden changes in the grid, the LVRT (Low Voltage Ride Through) capability of the Wind Turbines is one of the prime requirements. Wind turbines attached to DFIG (Doubly Fed Induction Generators) are advantageous which have LVRT capability at limited extent. In this paper, the elaborated discussion of the LVRT of Wind turbines shafted to DFIG's in the Grid. It also presents the complete description of the sudden changes in the systems like transient characteristics and the Doubly Fed Induction Generators dynamic response at the time of grid voltage faults (Symmetrical and Asymmetrical). The latest rotor side control technology is displayed in this paper for DFIG and wind turbines with improved capacity of low voltage ride through at the time of severe grid voltage sags. A Fuzzy Logic controller-based control technology is introduced in this paper which performs the balancing the rotor-side voltage and short circuits during the disturbances in the Grid. The advantage in this proposed control scheme is that it reduces the additional cost and reliability issues. So, the DFIG is efficient and usability company norms are satisfied with the proposed Fuzzy logic controller compared to regular controller like PI controller. The performance of the proposed system is simulated and verified in the computer. The results are displayed and it conclude that the control strategy of LVRT capability for Grid connected DFIG based wind turbine systems with Fuzzy Logic Controller are more effective than the conventional control Methods.


Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2356 ◽  
Author(s):  
Ferdinando Chiacchio ◽  
Fabio Famoso ◽  
Diego D’Urso ◽  
Luca Cedola

Grid-connected low voltage photovoltaic power plants cover most of the power capacity installed in Italy. They offer an important contribution to the power demand of the utilities connected but, due to the nature of the solar resource, the night-time consumption can be satisfied only withdrawing the energy by the national grid, at the price of the energy distributor. Thanks to the improvement of storage technologies, the installation of a system of battery looks like a promising solution by giving the possibility to increase auto-consumption dramatically. In this paper, a model-based approach to analyze and discuss the performance and the economic feasibility of grid-connected domestic photovoltaic power plants with a storage system is presented. Using as input to the model the historical series (2008–2017) of the main ambient variables, the proposed model, based on Stochastic Hybrid Fault Tree Automaton, allowed us to simulate and compare two alternative technical solutions characterized by different environmental conditions, in the north and in the south of Italy. The performances of these systems were compared and an economic analysis, addressing the convenience of the storage systems was carried out, considering the characteristic useful-life time, 20 years, of a photovoltaic power plant. To this end the Net Present Value and the payback time were evaluated, considering the main characteristics of the Italian market scenario.


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