SU1080232A1 - Device for clamping static overload of power transmission - Google Patents

Abstract

A &T; STATIC ELECTRIC TRANSFER CIRCUIT FUNCTION, containing a series-connected angle sensor, a maximum angle relay and a time relay, which is based on the fact that, with Zelky 'speed control, it is equipped with a logical element OR and a series-connected slip sensor a negative slip latching relay, a logical element AND, and a second time relay whose output is connected. to the input of the logical element OR, to the other input of which the output of the first time relay is connected, to the second input of the logical element AND the output of the relay of the Macromg. corner is connected, while: the output of the logical element OR is the output of the device.

Description

The invention relates to electrical engineering, in particular to emergency control automation of power systems. The devices for fixing static overload of power transmissions are known. Their principle of operation is based on fixing the excess of the active power of the transmission to a certain value of l. However, these devices are not sensitive due to the fact that when the stability is disturbed, the power is active due to its non-linear dependence on. the angle cannot exceed a certain maximum, after passing through which it decreases again, and its rate of change changes its sign from positive to negative. Compared to this principle, the use of coal and slip has the advantage that, when a violation of stability occurs, the angle increases monotonically, and the slip is always positive. The device closest to the invention in technical essence and to a achievable effect is a device that fixes the static transmission overload by increasing the angle between the capital expenditures in the starting and transmitting parts of the power system. This device contains a series of angle sensors, a maximum angle relay and a time relay. False alarm at short circuit is prevented in the specified device due to the action of the devices themselves. with a time delay, it is provided to ensure its selectivity. However, the time delay, which must exceed the time during which the triggering condition is fulfilled during synchronous swings, is long enough that the device has a disadvantage. The purpose of the invention is to increase the speed of the device. The goal is achieved by the fact that the device for fixing the static overload of power transmission, containing a series-connected angle sensor, maximum angle relay and time relay, additionally contains an OR logic element and a series-connected slip sensor, a negative-sign slip relay relay, an AND gate and a second time relay, the output of which is connected to the input of the OR logic element, to the other input of which the output of the first time relay is connected, to the second input of the logic element And a maximum angle relay output is connected, and the OR gate is the device output. Figure 1 shows the block diagram of the device; figure 2 - graphs, explaining the principle of operation of the device. The device contains an angle sensor 1 connected in series, a maximum angle relay 2, a time relay 3, the input of which is connected to an input of an OR 4 gate and a series-connected slip sensor 5, a latching relay from the flashing sign of a slip b, a logic element. AND 7 and a second time relay 8, the output of which is connected to the second input of the logic element OR 4, the output of which is the output of the device. Wherein . the second inputs of the maximum angle relay 2 and the slip sign latching relay 6 are connected to a blocking device in case of malfunction of voltage circuits 9, and the output of the maximum angle relay 2 is connected to the second input of the logic element AND depending on the nature of the transient process shown in Fig. 2, where curves a and a-1 characterize a slow aperiodic violation of static stability, which proceeds at a very low speed (slip.). A fast violation of stability, characterized by an increasing value of slip, is shown by curves b, bg1, and a stable oscillatory process, characterized by a maximum amplitude of synchronous oscillations and a change in sign, is shown by curve c, b-1. The curves shown in FIG. 2 may be distorted by superimposed subharmonics due to the multi-power system of the power system. In the process similar to the depicted curve a, a-1, the angle sensor 1 operates and when the angle S, obtained at the output of the sensor, exceeds the set value BC.U, the relay of maximum angle 2 operates and starts the first time relay 3 and the second relay time, or 8, because the signal at the second input of the logic element And 7 is not removed due to the fact that the relay fixing the negative sign of the slide 6 does not work. After the operation of the second time relay 8, which has a delay, the time t2kt, which is shorter than that of the first time relay 3 (), a signal appears at the output of the logical element OR 4. If the average increase in the angle S is slow with fluctuations around the mean value and the latching relay of a negative slip sign b is sensitive enough

And briefly periodically operates, removing the signal from the second input of the logic element 7, then the second, time relay 8 does not have time to dial the time delay specified for it / and the first relay {time 3 with time delay is triggered, and at the output of the logic element OR 4 ; device triggering signal; If the process of breaking static stability goes with a sufficiently fast increase of the angle S and slip S, like the process reflected by curves 8 and 5-1, then the device operates with a time delay set at the second time relay 8.

The device fails to function if, before the time delay expires at the second time relay 8, the negative slip sign b latching relay is activated and breaks its circuit, the start, and also if the time relay at the first time relay 3 (greater than for relay 8), it returns the maximum maximum angle 2 (,) and also breaks the start circuit of relay 3. The change of the slip sign, increasing and then decreasing the angle 8 means synchronous oscillations, i.e. sustainability. A similar process is depicted by curves in and in-1 in figure 2.

Thus, with synchronous swings, the device does not work, so

| As the time delay of the second relay (Time 8 is chosen longer than At,. For which; the condition for the failure of the relay to fix the negative slip sign b is fulfilled, and the time delay of the first time relay 3. selects a longer interval during which The condition for triggering the maximum angle relay is 2.

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Since the time delay at the second time relay 8 is approximately two times less than the time delay at the first time relay 3, the proposed device, compared with the prototype, has a high speed.

A static overload locking device can now be implemented on typical hardware.

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From the foregoing, it is clear that this proposal makes it possible to reduce the time delay by about 2 times, i.e. increase the speed, thanks to which it becomes possible to reduce the load shedding by emergency control automation, which creates a significant economic effect due to the reduction of damage.

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one

The proposed invention also improves the reliability of the device by preventing it from malfunctioning with faults.

5 voltage measuring circuits.

u & pod

Claims (1)

DEVICE FOR STATIC OVERLOADING OF THE ELECTRIC TRANSMISSION LOCATION, containing an angle sensor, a maximum angle relay and a time relay, which is characterized in that, with the Purpose! * To improve performance, it is equipped with an OR logic element and a slip sensor, a negative slip detection relay, a logical element And the second time relay, the output of which is connected, to the input of the OR logic element, to the other input of which the output of the first time relay is connected, to the second input of the second element AND the output of the maximum. angle relay is connected, while the output is logical. The OR element is the output of the device. ^{1st 2} n - --— j 3 ----- E. 3L ·! 5 6 3 7 -> 8 —J / fie. 1 10.80232