System for controlling and protecting against symmetrical and asymmetrical faults for asynchronous-type generators

Claim 1

A control and protection system in the event of symmetrical and asymmetrical faults, for doubly fed asynchronous generators, whose stator is connected to the grid and comprising: - a three-phase inverter (2). - an intermediate converter circuit (3) formed by a DC BUS and which serves to couple the inverter (2) with - a three phase rectifier (1) - a crowbar (5) to maintain control of the generator (7) during the symmetrical and asymmetrical faults and to prevent its disconnection from the power grid. - a central control unit (CCU) (8) responsible for governing the system component parts; which is characterised because: a). there is a controller block (5) connected to the crowbar (6), this block controls the absorption of the initial energy that appears when a fault occurs, this controller block comprises parallel branches made up of a 1 ) resistor devices (R ) for short-circuiting the rotor of generator (7), a 2 ) electronic devices (Q) with a cut-out function to control the said resistor devices; b) the control unit (8) comprises the means to capture, at least, the following electrical variables: grid voltage, rotor current, stator current of generator (7), voltage of intermediate circuit (3), voltage of crowbar (5) and that of the variables of controller block (6), and the means to ensure that, should any of the said electrical variables go out of the pre-established operating limits, then the resistor devices (8) would be activated, to ensure that the rotor voltage does not reach a value that would allow the rotor current to travel to the converter intermediate circuit (3).