32 Fault response of grid-connected squirrel cage wind-power induction generator Nagwa F. Ibrahim 1 , Ali. H. Kasem Alaboudy 1 , Hossam M. Attia 1 , and Sobhy S. Desouky 2 ABSTRACT This paper presents fault response of squirrel cage induction generator through grid connected of wind power. Thus, the Squirrel Cage Induction Generator (SCIG) is connected to an infinite bus through delta grounded wye transformer, transmission line and load. The capacitance compensation will be installed. The simulation model of grid connected squirrel cage wind power induction generator is discussed in the stationary reference frame using (MATLAB/SIMULINK). Simulations results have been investigated by various symmetrical and unsymmetrical faults. The fault is applied to the induction generator terminals. The paper introduces various types of algorithms to calculate the currents, frequencies and voltages in order to protect the wind driven induction generator connected to a power system grid. Keywords— squirrel cage induction generator (SCIG), short-circuit, fault, protection Algorithms 1. INTRODUCTION Recently, it is realized that world’s oil supplies would not last forever and that remaining supplies should be conserved for petrochemical industry. Other energy resources like coal and nuclear energy present serious environmental problems. These are the motivations behind considering the new energy resources like wind energy, solar energy, falling water energy, bio-mass energy and other energy alternative energy. The wind is a free, clean and inexhaustible energy source [1]. due to its reduced cost, its brushless rotor, absence of separate dc source for excitation, ruggedness, and ease of control and maintenance, squirrel cage-type induction generators have emerged as suitable candidates for wind turbine generation. This is because it bears the fluctuating wind and it cannot afford the fault transient, due to hauled to the reactive power, and increasing number of relatively (SCIG) connected to the power grid at the distribution level [2]. The induction generators require essentially no controls other than a contactor to connect the machine. The induction generator, like a synchronous generator, requires excitation in order to produce voltage and become a source of electrical power [3]. 1 Electrical Power, and Machines Department, Faculty of Industrial Education, Suez University, Suez, Egypt, E-mail: eng.nagwafadl@yahoo.com ali_hkasem@yahoo.com hossam65eg@yahoo.com 2 Electrical Power, and Machines Engineering Department, Faculty of Engineering, port said University, Egypt, E-mail: sobhyserry@yahoo.com The operation of connecting an induction generator with the utility grid is simpler than that of synchronous generator. Under fault conditions, the current drawn by the induction generator to provide its excitation is frequently reduced. For a three phase fault, current cannot be transferred past the fault point of the induction generator, therefore the unit loses its excitation. If the unit is provided with capacitors, fault would quickly cause these to be discharged, again resulting in removal of excitation from the generator [4]. Protection of an induction generator based system differs significantly from a similar plant with a synchronous generator. Many traditional protective devices are unnecessary because of the fundamental differences in performance between induction and synchronous generators. Examples of relays are not required for an induction generator, such relays included loss of excitation, synchronizing check and voltage balance [4]. Former studies were of limited range and, at the same time, they mostly focused on the protection of doubly fed induction generators (DFIG) e.g., crowbar protection is a well know method in (DFIG) protection. Sattar et.al. [5] presented the crowbar and its usage when it comes to protecting the rotor converter against short circuit current during faults. They found that the stator and rotor transient current decay rapidly to value with amplitude less than one pu and rotor circuit is properly protected when the crowbar is activated. Krisztina [6] presented dump resistor protection the crowbar and dump resistor and using it to protect the rotor converter against short circuit current during faults. By Comparing crowbar to dump resistor, it is concluded that the dump resistor is best than that crowbar protection [5]. Microprocessor relay is a well-known method in (SCIG). Attia [7] presented the protection of the induction generator against short circuit current, under voltage, over/under frequency and negative sequence PORT SAID ENGINEERING RESEARCH JOURNAL Faculty of Engineering - Port Said University Volume 18 No. 2 September2014 pp:32 : 41