SU119221A1 - Device for automatic unloading of the energy system at a lower frequency - Google Patents

Description

Automatic unloading of electric power systems by frequency cannot ensure proper restoration of the frequency in transient and emergency modes of the system with a deficit of active power, due to the instability of both the system load and, in particular, the connections interlocked with automatic unloading machines, and the power of regulation and reserve of the system.

Each stage of the system unloading is calculated according to the frequency reduction that may occur in this particular system, and consumers are connected to each stage of the automatic unloading device, the disconnection of which should restore the frequency to a certain acceptable limit. Unnecessary disconnection of consumers during the operation of unloading machines is unacceptable. It is also unacceptable to arbitrarily change the order of disconnection of consumers, which is set strictly for reasons of importance, responsibility and the possibility of technical and safe operation of the consumers themselves.

However, under the conditions noted at the beginning, the frequency of the system, even with an automatic unloading action, can be set at a level significantly lower than allowed.

The peculiarity of the proposed device is that it provides a refinement of the queue of operation of individual stages for restoring the frequency in the system above the frequency level to which the first stage is tuned. For this, in each stage, one of the intermediate relays, controlled by a time relay and control unloading circuits, triggered last, is used to turn on the next stage time relays, which is able to operate independently of the frequency relay of this stage.

Thus, if, for example, the first stage works and the frequency is set below the frequency level of the first stage, but above the second, then

No. 119221

the second stage will start working and the system will be further unloaded until the frequency is restored to an acceptable level.

The drawing shows a schematic diagram of the proposed device with three stages of discharge.

In the drawing, the numbers 1, 2 v (3 denote frequency relays of three stages of unloading; 4, 5 6 are time relays, which are used to turn on the corresponding intermediate relays 7, 8, 9 of the first stage, intermediate relays Yu, 11, 12 of the second stage and intermediate relays 13, 14, 15 of the third stage (relay 7-V5 controls the discharge circuit), relay 16 is an intermediate time relay.

When lowering the frequency below the set point of the first stage, the relay triggers the frequency and, consequently, time relay 4, which, according to the time settings (exposure), supplies power to the intermediate relay 7.8 to 9.

The intermediate relay 7 closes its contacts and disconnects the connection of the first stage. If the frequency rises above the relay setting / over time, the discharge action will cease. Otherwise, i.e., if, after the first stage is disconnected, the frequency does not increase at all above the first-stage setpoint (and, in particular, in time), then relay 8 trips, disconnecting another number of connections (1 ' time-up, ti- the transition time of the slip contact relay 4 time).

If and after that the frequency does not increase (or rises slowly, and the rise time), then relay 9 operates, which supplies power to relay 5 of the second stage of discharge, / y - the response time of the relay 9).

Thus, although the frequency does not fall below the setpoint of the second stage, it is still possible to unload the connections of this stage. This is the main see list of the queuing queue, since the subsequent queues are actually the specifying queues of the unloading itself. The subsequent action of the other stages and queues is quite similar to that described above.

With a significant decrease in frequency, all the queues of each stage can be switched off alternately. In this case, locking relays 9 and 12 play the role of duty relays for the action of the refinement queue. If, for example, the frequency drops below the second stage setting and, despite the operation of relays 7, 8, 10 and 11, it does not increase at all or during 1 "y, (since the frequency relay 2 operates) above the second stage frequency setting (relay 2 The relay 12, which supplies power to the time relay 16, triggers the last, according to the time settings, by means of the relay 13, 14 and 15 connecting the third stage (t is the time of the relay 12 operation).

If during the operation of the relay 7, 8, 10 and 11 the frequency increases, will remain below the set point of the first stage (relay 1), then the refining queue will work, since the relay 9 will energize the relay 5 time, which with the help of the relay 12 and 16 alternately disables the connections of the third discharge stage.

In cases of sharper frequency changes, when the latter drops below the setpoint of the third discharge stage, the first two steps work in the same way as described above. The third stage is triggered almost instantaneously, since the relay 3 frequencies, having closed their contacts, supplies power to the relay 6, and the latter, through the intermediate relays 13, 14 and 15, disconnects the interlocked connections without time lag.

It is possible to construct a relay unloading scheme with a refinement queue according to the proposed principle and for a larger number of stages.

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