SU1545284A1 - Device for protection of brushless synchronous machine against damage in excitation system - Google Patents

Abstract

This invention relates to electrical engineering and can be used to protect brushless synchronous machines. The purpose of the invention is to expand the functionality. This is achieved by introducing a single-threshold and two-threshold comparators, a voltage divider and a display unit. In emergency modes, the variable sensor signal does not remain in the set range — either exceeds the highest set potential at the divider, or becomes less than the lowest potential of the divider. The operation at the lowest level occurs when there is a short circuit on the outputs of the rotary rectifier or in the event of an open circuit in the excitation winding circuit of the synchronous machine. Triggering on the highest level occurs when the breakdown of the branches of a rotating converter or during an asynchronous course of the machine, associated with the loss of excitation in the event of a fault in the control unit. In both cases, the machine is turned off with a time delay, and a corresponding alarm appears in the display unit. 3 il.

Description

The invention relates to electrical engineering and can be used to protect brushless synchronous machines having an auxiliary alternator and a rotating semiconductor rectifier, such as a synchronous driver, in the event of damage to the fixed and rotating parts of the excitation system.

The purpose of the invention is to expand the functional capabilities by providing protection in case of failures in the control unit, break of the excitation winding circuit, breakdown of the valve of the rotating rectifier, short circuit on the outputs of the rotating rectifier,

Fig. 1 is a block diagram of a brushless synchronous machine and device for protecting it from damages in the excitation system; Fig. 2 shows embodiments of separate units of the device; on - dependence of the excitation voltage on the excitation current

The brushless synchronous machine (BCM) contains the machine 1 itself, the rotating rectifier 2, the synchronous exciter 3, the control unit 4

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sensors 5 and 6 of constant and variable components of the exciter excitation current, voltage divider 7, two threshold comparator 8 with OR circuit for two inputs, single threshold comparator 9, delay unit 10, actuator II, alarm unit 12, brushless switch 13 synchronous machine, while the two-threshold comparator consists of two single-threshold 14 and 15 comparators. The non-inverting input of the first single-threshold 14 comparator is connected by the voltage divider 9, terminal 16, and the output 17 is connected to the inverting input of the second single-threshold comparator 15. The two other inputs of single-threshold comparators receive a signal from a variable component sensor.

The device works as follows

In the normal mode of operation of the BCM, a current flows through the excitation winding of the exciter, which contains a constant and a variable component. The constant component is determined by the rectified voltage value of the control unit and the active resistance of the exciter winding. The variable component is determined by the phase current of the synchronous exciter and is proportional to the excitation current of the BSM and is due to the characteristics of the exciter through the rotating rectifier to the excitation winding (rectifying load). In the current there is also a variable component associated with the ripple of the rectified voltage of the control unit, however, this variable component can be neglected, since the inductive resistance of the excitation winding 1, the exciter at the pulsation frequency is rather large compared to its active resistance. The variable and constant components of the excitation current of the exciter are extracted by means of sensors 5 and 6, which receive signals from a resistor having resistances 1-2 times less than the active resistance of the excitation winding of the exciter and connected in series in its circuit. The variable component is amplified and transformed into a constant voltage. The signals from sensors 5 and 6 are fed to a two-threshold comparator 8. In this case, the lowest, non-zero

the potential of the constant component taken from pin 16 of divider 7 is fed to the non-inverting input of the first single threshold 14 comparator included in the two-threshold comparator 8, and the highest potential of pin 17 of the divider is fed to the inverting input of the second single threshold 15 comparator. The two other inputs of single-threshold comparators receive an adjustable variable sensor signal. When setting the protection circuit in the nominal mode of operation of the BCM, the variable signal level of the variable component sensor is selected equal to the arithmetic mean value of the lower and higher potentials taken from the 7 divider. In the normal mode, the BCM variable sensor component is in the range and lower levels of the potential of the divider (Fig. 3), where i {n is the excitation current of the exciter; 1Gvmn "; if8Mt wH ifbmM-, respectively, its minimum allowable, nominal and force values; Uq is the voltage of the sensors of the constant and variable components of the excitation current of the exciter; Ug, c, nc potential resistance divider; U Q-WUH lowest potential divider; U, - Stress the variable sensor; Uonop is the reference voltage supplied to the single-threshold comparator 9, In this case, there is no signal at the output of the two-threshold comparator. In emergency conditions, the variable sensor signal does not remain in the specified range; either exceeds the highest installed potential on the divider, or becomes less than the lower potential of the divider. In the first case, the second single-threshold comparator is switched and a positive potential appears at its output, which through the OR circuit and time delay unit 10 triggers the actuator 11. In the second case, the protection is triggered by the signal of the first single-threshold comparator. And the „/ rank of the divider 7 occurs during a short circuit at the terminals of a rotating rectifier. In this case, the currents of the driver's phases become sinusoidal, in contrast to the normal mode, when they have

shape close to rectangular. The variable component decreases sharply and a two-threshold comparator is triggered on the lower divider level. A similar situation arises when the excitation winding of the synchronous machine is broken, for example, when the interpolar jumper is broken, when the sensor signal of the constant component retains its value, and The variable component sensor generates a signal associated only with the ripples of the rectified voltage of the control unit, which can be neglected. The protection is triggered at the highest level U. The MO-NS divider 7 occurs when the valve of the rotating rectifier 2 breaks down or when the machine runs asynchronously when the exciter is lost due to faults in the control unit 4.

When an exciter winding circuit breaks or a control unit fails to cause the machine to disengage, when it continues to rotate at a synchronous speed at a reactive moment without load, the signals of the constant and variable components of the sensors become equal to zero and voltage, a single-price comparator 9 is switched, the signal of which through the delay unit triggers the actuator 11. The introduction of a two-threshold 8 and a single-threshold 9 computer into the protection circuit ATOP allows you build certain kinds of damage to the drive system of BSM.

To indicate the type of damage and store information about it after the machine has been disconnected from the network by the executive body 11 acting on the switch 13 of the synchronous machine, the alarm unit 12 is entered into the protection circuit. In the block there are three AND circuits for two inputs according to the number of single-threshold comparators in the device . Signals of the corresponding single-threshold comparators are delivered to their first inputs, the signal of the executive authority 1I is applied to the second inputs. If the excitation system is damaged after

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and the trigger point, determined by the installation of the delay unit 10, and the actuator fails to operate on one of the I circuits. Two signals are received, switching in in, with a corresponding indication and storing information about the type of damage in the excitation system upon subsequent shutdown of the switch 13 BCM from the network.

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Claims (1)

Invention Formula A device for a brushless synchronous machine to be damaged in an excitation system with a thyristor control unit supplying the excitation winding of the exciter with a rectified current, containing sensors of the exciter constant and variable components of the excitation current to be connected to the control unit, a time delay block whose output is connected to an actuator whose output is intended to be connected to a control unit and a generator switch, characterized in that, in order to expand the function potential opportunities by providing protection in case of failures in the control unit, interruption of the field of the excitation winding, short circuit and breakdown of the rotary rectifier valve, single-threshold and two-threshold comparators, voltage divider, alarm unit are additionally introduced, and the actuator has an additional output that is connected to the first the input of the alarm unit, the second input of which is connected to the first output of the single-threshold comparator, the second output of which is connected to the input of the delay unit, which is connected It is also connected to the output of a two-threshold comparator, the other two outputs of which are connected to the second and third inputs of the alarm unit, and the output of the DC component is connected to the input of a single-threshold comparator and, through a voltage divider, to the first input of a two-threshold comparator, the second input of which is connected to the output variable component sensor. 1 JT mVA ™ bin iff Figure 3 Compiled by S. Evdokimov. Editor L.Gratillo Tehred L.Svrdyukova Corrector O. Tsiple Order 495 Circulation 471 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 Fig.} -4 th FIG, g hmaks Normal Subscription