RU2222088C1 - Synchronizing relay - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: synchronizing relay has measuring transducer, adder, comparator, final element, and three averaging and residual-signal shaping units. Relay incorporates provision for eliminating impact of short-time failure of generator frequency and high-frequency noise on its operation. EFFECT: enhanced precision. 1 cl, 2 dwg

Description

 The invention relates to electrical engineering and can be used as a generator synchronization relay when it is connected to the network.

 A device is known that contains a series-connected clock generator, a binary counter, a decoder, a pulse shaper and an actuator made in the form of a transistor [1].

 The disadvantage of this device is the relatively narrow functionality that does not allow using it as a synchronization relay.

 The closest in technical essence to the proposed device is a device containing a series-connected measuring transducer, a first differentiation unit, a second differentiation unit, an adder, the second and third inputs of which are connected to the outputs of the measuring transducer and the first differentiating unit, a comparator and an actuator [2].

 The disadvantage of the closest technical solution is the relatively low accuracy in the conditions of short-term malfunctions in the phase mismatch of the network and generator signals or high-frequency interference.

 The technical result of the invention is to increase accuracy.

 This technical result is achieved in that in a device containing a measuring transducer, the first and second inputs of which are inputs for connecting a network signal and a generator and designed to convert the phase angle between the mains voltage and the voltage of the generator into a constant voltage, and a series-connected adder, comparator and an actuating element, the first, second, and third blocks of averaging and generating a difference signal are introduced.

 In this case, the input of the first block of averaging and generating a differential signal is connected to the output of the measuring transducer, the first output is connected to the first input of the adder, and the second output is the input of the second block of averaging and generating a difference signal, the first output of which is connected to the second input of the adder, and the second output - with the input of the third block of averaging and the formation of a difference signal, the first output of which is connected to the third input of the adder.

 Moreover, each of the first, second and third blocks of averaging and generating a differential signal is made in the form of series-connected subtraction units, the first input of which is the input of a block of averaging and generating a difference signal, an adder and an averaging filter, the output of which is the first output of the averaging and generating unit a difference signal and is connected to the second inputs of the adder and the subtraction unit, the output of which is the second output of the averaging unit and the formation of the difference signal.

 In FIG. 1 is an electrical block diagram of a synchronization relay; in FIG. 2, an averaging and differential signal generating unit.

 The synchronization relay (figure 1) contains a series-connected measuring transducer 1, the first block 2 of averaging and generating a differential signal, an adder 3, a comparator 4 and an actuating element 5, the second block 6 of averaging and forming a difference signal, the input of which is connected to the second output of the first block 2 averaging and generating a differential signal, and the output is connected to the second input of the adder 3, and the third block 7 averaging and generating a differential signal, the input of which is connected to the output of the second block 6 of averaging and the formation of a differential signal, and the output is connected to the third input of the adder 3.

 The first 2, second 6 and third 7 blocks of averaging and generating the differential signal (Fig. 2) are made in the form of series-connected subtraction units 8, the first input of which is the input of the said block, adder 9 and the average filter 10, the output of which is the output of the said block and connected to the second inputs of the adder 9 and the subtraction unit 8, the output of which is the second output of the said block.

 The actuating element 5 can be made in the form of a relay winding with corresponding contacts, which is connected to the output of the comparator 4 through the amplifier and an element with a changing state (for example, a transistor with a zero initial state) turned on at its input. Measuring transducer 1 performs phase shift angle conversion δ between the mains voltage and the voltage of the generator into a constant voltage Uδ and may have the same design as in the prototype. In the analog execution of block 8 subtraction, its input is weighted. As the filter-averager 10 can be used a low-pass filter. With the digital version of the device, an analog-to-digital converter is turned on at the output of the measuring transducer 1, the subtraction units 8 have a weighted first input, and the averaging filters 10 can be made in the form of a standard digital non-recursive filter containing series-connected shift register cells, the outputs of which are through the corresponding multipliers by 1 / k, where k is the number of filter cells, connected to the input of the adder, the output of which forms an estimate of the average value of the received counts to the moving average time interval moving in time. The remaining units of the device are standard units of electrical engineering. The power supply circuits of the blocks in the drawing are omitted as non-essential in the framework of this application. Similarly, non-essential synchronization circuits of digital elements are omitted when using the digital version of the device.

 The synchronization relay operates as follows.

When the relay is switched on, the signal Uδ is formed at the output of the measuring transducer 1, the value of which is proportional to the phase difference of the voltage signals of the generator and the network [2; p. 351, fig. 12. 12; p. 352, fig. 12. thirteen]. As shown in the known literature [2, p. 352], the condition for turning on the generator with a delay by a given value t _op , ensuring synchronization of the generator and the network is the following equality:
Uδ + (dUδ / dt) • t _op + (d ² Uδ / dt ² ) • t $\genfrac{}{}{0ex}{}{\text{2}}{\text{op}}$ / 2 = U _2π ,
where dUδ / dt, d ² Uδ / dt ² are the first and second derivatives of Uδ;
U _2π is the value of Uδ when the phase difference between the voltage signals of the generator and the network is 2π (0).

 The sum indicated on the left side of this equation is formed at the output of the adder 3. Previously, the signal Uδ passes sequentially through the subtraction unit 8 and the adder 9 of the first unit 2 and does not change (since the same signal from the filter output is subtracted from it and summed with it) averager 10) is fed to the input of the averaging filter 10, in which high-frequency interference of various nature is smoothed. Therefore, the first input of the adder 3 from the first block 2 receives a free from high-frequency interference estimate of the value of Uδ.

In addition, the signal from the output of the side of the subtraction 8 of the first block 2 is fed to the input of the second block 6, from the output of which the second input of the adder 3 receives an estimate of dUδ / dt. Similarly, at the output of the third unit 7 formed estimate of d ² Uδ / dt ² which is supplied to the third input of the adder 3, the resulting signal from the output of which is compared in a comparator with a threshold value U _2π. At the moment of equality, a short impulse is formed at the output of comparator 4 with a logic unit level, leading to the actuation of the actuating element 5. This ensures a synchronous connection of the generator to the network.

 Thus, in the proposed technical solution, the accuracy increases, since the influence of short-term malfunctions of the generator frequency and high-frequency interference on the relay operation is eliminated.

Sources of information
1. Electrical reference book, in 4 volumes. T.2: Electrical products and devices. Under the total. ed. V.G. Gerasimova et al. - M.: Publishing House MPEI, 1998, p. 390, fig. 35.10.

 2. Andreev V.A. Relay protection and automation of power supply systems. - M.: Higher School, 1991, p. 352, fig. 12.13 (prototype).

Claims (1)

A synchronization relay containing a measuring transducer, the first and second inputs of which are inputs for connecting a network signal and a generator and designed to convert the phase angle between the mains voltage and the voltage of the generator into a constant voltage, and serially connected adder, comparator and actuator, characterized in that the first, second and third blocks of averaging and generating a differential signal are introduced, while the input of the first block of averaging and generating a difference signal connected to the output of the measuring transducer, the first output of averaging and generating a differential signal is connected to the first input of the adder, the second output to the input of the second block of averaging and generating a difference signal, the first output of which is connected to the second input of the adder, and the second output to the input of the third averaging block and the formation of a differential signal, the first output of which is connected to the third input of the adder, with each of the first, second and third blocks of averaging and the formation of the differential signal fln in the form of series-connected subtraction unit, the first input of which is the input of the averaging and generating a difference signal, adder and averaging filter, the output of which is the first output of the averaging and generating a difference signal and connected to the second inputs of the adder and subtraction, the output of which is the second output of the block averaging and the formation of a differential signal.

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