RU2014707C1 - Equipment for automatic synchronization of synchronous generators - Google Patents

Abstract

FIELD: electric power engineering. SUBSTANCE: equipment includes pulse formers 1,2 to which inputs voltages of synchronized sources U1_in and U2_in are fed, logic AND gates 3 and 4 which outputs are correspondingly connected to outputs of pulse formers 1 and 2 which form signals of positive and negative polarity and which outputs are linked to first input of logic AND gate 5, threshold element 6 which inputs are connected to difference of synchronized voltages, time delay element 7 with restarting which input is coupled to output of threshold element 6 and output - to second input of logic AND gate 5. EFFECT: improved operational efficiency. 2 dwg

Description

 The invention relates to the electric power industry / in particular to the field of automatic synchronization of synchronous generators.

 A device for automatically synchronizing synchronous generators / generating a signal to turn on the generator switch when the phases and frequencies of the synchronized voltages coincide. The synchronizer consists of an input device / containing pulse shapers and a phase matching control unit / and an enable unit / containing a frequency difference control unit / threshold element and an actuator [1].

 The specified device has several disadvantages: the use of a half-wave rectifier in the circuit for comparing the voltage of generators can lead to the inclusion of generators in antiphase; frequency equality control circuit / using an integrating circuit / causes a delay in switching on the circuit breaker / a when switching on again due to a possible residual voltage across the capacitor, switching on at an unacceptable frequency difference is possible.

 There is also a device for protecting against nonsynchronous inclusions for parallel operation / containing two rectangular pulse shapers with inputs for connecting to the mains voltage and the generator / the first logical element And / with the first input connected to the output of one of the rectangular pulse shapers / and the second inverting to the output of another shaper pulses / the second logical element AND / one input of which is connected to the output of the first logical element And through the one-shot / and the other - directly includes ement time delay [2].

 The disadvantage of this device is that / the control of the angle of the phase difference between the synchronized voltages is carried out once during the period / which reduces the speed of protection. In addition / during load shedding or surge, transients occur in the networks / which can lead to voltage fluctuations or distort the shape of the voltage curve / which leads to a shift in the moment of transition through zero and to false signal output due to the lack of control of the voltage difference of the sources. The disadvantage is the uncertainty of the moment of inclusion / and therefore / inefficiency of the use of high-speed switches.

 The purpose of the invention is to simplify the device / increase the reliability and speed of inclusion in parallel operation of synchronized networks.

 This is achieved by additionally introducing a time delay element with a restart / threshold element / with the output of the first pulse generator / determining the passage of the beginning of the negative half-waves of the generator voltage / connected to the first inverse input of the third logic element And / the output of the second pulse generator / determining the passage of the negative half-waves of the network voltage / connected to the second inverse input of the third logical element AND / outputs of the first and third logical elements And connected connected with the first input of the second AND gate / the second input of which is connected through the delay element to restart with the output of the threshold element / switched on to the difference of the synchronized voltages.

Considering the difference between the phases of the same name of the rectified sinusoidal voltage of synchronized sources / as a sequence of positive pulses / changing their amplitude over time (depending on the slip and voltage difference) / connect to them the input of the threshold element / the output of which is connected to the input of the delay element with restart. Having a sequence of positive pulses at the input of the delay element with restart / synchronized voltages determined by the parameters and the value of the set sensitivity threshold U _then / at the output of the delay element with the restart, a low voltage level / determined by the frequencies of the synchronized sources and the minimum delay time τ _{s is} obtained. When the delay element disappears at the input with restarting positive pulses after a time τ _s , a high voltage level appears at the output / corresponding to the moment of synchronization of sources.

The value of U _then determines the maximum difference of the synchronized voltages / at which synchronization is possible / i.e. performs the function of controlling the voltage difference of synchronized sources.

The value of the delay time τ _s determines the blocking of the inclusion with a significant amount of slip synchronized sources. Therefore, this connection of elements with the choice of the corresponding U _pores and τ _s provides the monitoring of compliance with all synchronization conditions.

 In FIG. 1 presents a diagram of the proposed device; figure 2 is a diagram / explaining the operation of the device.

The device contains drivers 1 and 2 pulses / the inputs of which are supplied with voltage U1 _I and U2 _{I of} synchronized sources / logic elements 3 and 4 / whose inputs are connected to the outputs of the drivers 1 and 2 / and the outputs are connected to the first input of the logic element And 5 / threshold element 6 / whose inputs are connected to the voltage difference of synchronized sources / delay element 7 with restart / whose input is connected to the output of the threshold element 6 / and the output is connected to the second input of the logic element 5.

 The device operates as follows.

T_c/ где T_c - период напряжения сети.In the presence of voltages at the inputs, the drivers 1 and 2 form pulses of constant duration τ of positive and negative half-waves / whose leading edge coincides with the zero value of the instantaneous voltage U1 _in and U2 _in . To exclude the generation of a turn-on signal in antiphase, logic elements 3 and 4 / are used which compare pulses of positive and negative half-waves of voltages. The frequency difference of the synchronized voltages leads to the fact / that the pulses are shifted with respect to each other over time. The duration of the synchronizing pulses τ (figure 2) determines the moment of "advancing" the signal to turn on the switching equipment. The threshold element 6 rectifies the resulting voltage of the same phases of the synchronized sources and converts into pulses / whose width is determined by U _then (figure 2) and the value of the resulting voltage U (figure 2). The pulses from the output of the threshold element 6 are received at the input of the element 7 of the time delay with a restart. The leading edge of each pulse restarts the time delay element 7 so that its output enable signal is absent at the output. If the resulting voltage U of the synchronized sources is less than U _pores / then the threshold element 6 stops issuing pulses / restarting the delay element 7 / and after a delay time τ _{s a} high level signal appears on the second input of the logic element And 5 / allowing switching on of switching equipment. The delay time τ _s (Fig. 2) is determined by the maximum allowable slip value of the synchronized sources and must correspond to the ratio

T _c / where T _c - period of the mains voltage.

The value of the sensitivity threshold U _then is determined by the allowable voltage difference of the synchronized sources.

In FIG. Figure 2 shows the synchronization moment of two sources of sinusoidal voltage with different frequencies. The inputs of the logic circuit And 5 receives signals from the logic circuits And 3 and 4 and from the delay element 7 with a restart. When the signals coincide at the output of the logic circuit And 5 there are signals U _o (Fig. 2) / characterizing the moment of passage of the voltage through the zero points for the difference between the frequencies and voltages of the sources being synchronized that are acceptable for synchronization.

Thus, the control of the coincidence of the moments of transition through zero of a sinusoidal voltage twice per period provides an increase in the switching speed for parallel operation / and the control of the difference in the instantaneous voltages of the synchronized sources provides a blocking of the inclusion when the frequency difference is invalid / as well as under the influence of transients or interference in synchronized networks. The blocking of the inclusion with a significant amount of slip determines the delay time τ _s .

 An automatic pulse synchronizer can be implemented as a universal unit / suitable when using any type of precision automation device.

 As functional elements of the given structural diagram, ready-made functional units in the form of integrated circuits can be used.

 The proposed technical solution differs from the prototype in that it additionally introduces a third logical element AND / which compares the pulses / determines the passage of the beginning of the negative half-waves of synchronized voltages / hence / compares the pulses every half of the period / which increases the speed and determines the signal to be switched on when synchronized voltages through zero.

 The introduction of the threshold element / included in the difference between the rectified synchronized voltages / the output of which is connected to the input of the delay element with a restart carries out the synchronization moment / as well as the prohibition of the switching signal when short-term surges and voltage dips occur / which is absent in the prototype.

Claims (1)

 DEVICE FOR AUTOMATIC SYNCHRONIZATION OF SYNCHRONOUS GENERATORS, containing two pulse shapers with inputs for connecting respectively to the mains and generator voltage, the first logical element And, the first input of which is connected to the first output of the first pulse shaper, which determines the beginning of the passage of positive half-waves of the generator voltage, the second input is connected to the first output of the second pulse shaper, which determines the passage of the beginning of the positive half-waves of the mains voltage, the output of which is under It is connected to the first input of the second logical element And, characterized in that it additionally contains the third logical element And, a delay element with a restart, a threshold element, and the second output of the first pulse generator, which determines the passage of the beginning of the negative half-waves of the generator voltage, is connected to the first inverse input of the third logical element And, the second output of the second pulse shaper, which determines the passage of negative half-waves of the mains voltage, is connected to the second inverse input t of the third logical element AND, the output of the third logical element And is connected to the first input of the second logical element And, the second input of which is connected through the delay element with restarting to the output of the threshold element connected to the difference of the synchronized voltages.

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