SU1297154A1 - Device for relay protection of traction networks - Google Patents

Description

I1

The invention relates to the automation of electric power supply devices for railways electrified on alternating current, and can also be used to protect short-circuit currents from lines of unpowered consumers.

The purpose of the invention is to increase the selectivity of protection in the power supply system.

Figure 1 shows the structural diagram of the proposed device; figure 2 - the timing diagram of his work.

The device for relay protection of traction networks contains intermediate current transformers (ПТТ) 1 and voltage (ПТН) 2, at the output of which the setting control unit 3 (BRU) is connected, connected via adder 4 to the controlled integrator 5, the first threshold element 6, connected through a delay line 7 and a pulse shaper 8 with an element AND 9, another input of which through the second threshold element 10 is connected to the output of the controlled integrator 5, and the output of the element AND 9 through the element OR 11 is connected to the actuator 12.

Figure 2 shows the signal 13, proportional to voltage, the signal 14 at the output of the adder, the signal 15 at the output of the first threshold element, the signal 16 at the output of the delay line, the signal 17 at the output of the controlled integrator, the signal 18 at the output of the second threshold element, signal 19 at the output of the pulse former, signal 2b at the output of the element And, and signal 21, which characterizes the state of the executive organ.

The device works as follows.

Signals proportional to the primary current from the output of the switchgear 3 and primary voltage from the PTN 2 are received on the go of adder 4. The setting control unit changes the signal size proportional to the primary current, which allows setting the corresponding setpoint of the relay. The DCU can be performed, for example, on the basis of a variable gain op amp.

Signals proportional to the primary current and voltage, summarizes the adder 4, the signal 14 at its output

542

equal to KjjUsiii (Ot + Kj.Isin (tot + J), where Ku and Kj are coefficients that show how many times the magnitude of signals proportional to voltage and current at the input of the adder is less than the primary current and voltage in the line; U and I - amplitude values of the primary voltage and current} co - frequency; t - time; - J - angle between current and voltage.

The controlled integrator 5 integrates the signal from the output of the adder 4. The integration time and its duration sets the signal 16 from the output of the delay line 7, which shifts by the time t, the signal from the output of the first threshold element 6. Thus, the integration duration is 0 5 T, where T is the period of compared values. If the signal 17 is positive, the second threshold element 10 is triggered at the output of integrator 5 and a low level signal 18 appears at its output. At the time preceding the end of the low level of the signal 16, the pulse shaper 8 generates a short low level pulse signal 19 at the output. When a low level of signals 18 and 19, arriving at the inputs of the element 9, coincides, the output of the latter appears as a low level signal 20 acting through the element OR 11 on the actuator (fig. 2a), which triggers the protection device (signal 21 low level).

In the event that the monitored resistance parameters in the np line exceeded the permissible values during the low level of signal 19, the value of the integral signal 17 at the output of the integrator 5 will be negative, respectively, the signal 18 at the output of the second threshold element will be low level and the output of the element And 9 there will be no command to turn off the high-voltage switch (Fig.25).

From the foregoing it follows that the boundary line of the response characteristic of the relay can be determined from the condition that the integral signal is equal to zero, i.e.

, + i: / iO

I KyUsincot + K jI-sin (cot + J),

tf,

from which one derives the boundary line equation of the response characteristic of the relay in the impedance plane Zi

(а.г4к;.), i 5

,

Where

Rg - line resistance -,

1 „- line current.

fO

This equation describes a circle passing through the origin of coordinates c. maximum sensitivity angle

, .15

Thus, by changing the time t, the angle of maximum sensitivity of the relay can be adjusted, and by changing K J, the resistance value of the relay setting.20

The application of the proposed device that implements a directional characteristic, povpat selectivity in relation to the short-circuit. on the adjacent path, and also provides an increase in the permissible feeder load current. In addition, when used, it improves the reliability of the operation of the entire power supply system.

Claims (1)

Invention Formula Device for relay protection of traction networks, containing intermediate 35 current and voltage transformers, pred5 O 15 0 five 0 5 assigned to connect to the protected network, a setting control unit, an adder, threshold elements, a controlled integrator, a pulse shaper, AND, OR elements and an actuator whose input is connected to the output of the OR element, one of the inputs of this element is connected to the output of the AND element and the remaining inputs of the OR element are connected to the outputs of the corresponding protection stages, one of the inputs of the AND element is connected to the output of the pulse former, and the other input is connected to the output of the second threshold element, whose input is connected to the output of the controlled integrator, and the input of the controlled integrator is connected to the output of the adder, one of the inputs of which is connected to the output of the setpoint control unit, and the output of the intermediate current transformer is connected to the input of the first threshold element, in order to increase the selectivity into the device additionally introduced a delay line, and its input is connected to the output of the first threshold element, its output is connected to the input of the impulse generator 1s And the control input of the controlled integrator, and the output the intermediate current transformer is connected to the input of the settings control, and the other input of the combiner is connected to the output of the intermediate traysfohmmator nal; wives C. / 5 DL 3J6 I IL Jll Editor A.Lezhnina Compiled by T. Shchegolkova Tehred A. Kravchuk Proofreader L. Patay Order 789J57 Circulation 619 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk-nab., d.4 / 5 gv t-ich | "CHI-- 1-P" t Production and printing company, Uzhgorod, Projecto st., 4 / 3 u: 20 21 FIG.