KR20100034303A - The protection scheme for asynchronizing of power generator - Google Patents

Abstract

PURPOSE: A generator asynchronous input protective device is provided to protect electric power facilities by rapidly cutting off current generated in an asynchronous input of a generator. CONSTITUTION: A protective device constitutes a pulse element signal or over-current relay operating signal with a AND logic signal. The pulse element signal is outputted during a designated time when the generator operating condition is satisfied. The over-current relay is embed in the digital protective device. The protective device applies an output signal to the lockout relay. A delay element(601) delays a generator operation condition signal for 1 second.

Description

[0001] The present invention relates to an asynchronous input protection device for a generator,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a generator asynchronous input protection device for rapidly protecting a power facility such as a generator and a transformer by rapidly breaking a large-capacity fault current generated when the generator is turned on in a power system in an asynchronous state.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a generator synchronization circuit configuration and a protection system technology for protecting a power facility such as a generator and a transformer. Generator synchronous circuit and protection system will be described in detail as follows.

1 is a block diagram of a generator synchronization PT circuit. 1, when 345kV # 7100 phase breaker is used for system feed, 345kV # 1BUS PT a phase voltage (10) and generator PT ab phase voltage (18) are used for synchronization check. When feeder is fed by circuit breaker # 7172 The 345 kV # 2 BUS PT a phase voltage 11 and the generator PT ab phase voltage 18 are used. When the system is fed into the generator GCB, the GDS primary PT ab phase voltage (17) and the generator PT ab phase voltage (18) are used for synchronization verification. If the voltage phase and magnitude at both ends of the synchronous circuit breaker are within the specified range, the mechanical motor 325 of the TCMS 16 (Turbine control monitoring system) operates.

When the synchronous relay operates, the breaker is turned on by using the contact of the synchronous relay. On the other hand, the breaker and DS contact in GIS LCP (12) (Gas insulator switch local control panel) and GCB LCP (13) (Generator circuit breaker local control panel) The contacts of the ECMS (Electrical control monitering system) (14) are circuits for selecting which circuit breaker to synchronize with and which circuit breaker to select. Auxiliary PT for voltage adjustment. The PT 15 is intended to match the magnitudes of both ends of the synchronous closing breaker. This is because the synchronous relay 325 of the TCMS 16 does not operate if the voltage magnitudes of the both ends of the synchronous closing breaker do not coincide with each other. Aux. PT 15 is used to compensate the difference between the 345 kV PT secondary voltage 115 V (10, 11) and the generator PT secondary voltage 120V (18).

As shown in FIG. 1, since the PT circuit for synchronizing the generator is connected to the synchronous relay 325 via a plurality of power facilities such as a breaker and a disconnecting switch, problems such as a wiring error or a faulty synchronous relay may occur in the field. The system is not equipped with a comparative protection system, resulting in a large loss such as the burnout of the electric power facility and the stoppage of the electric power generation at the time of asynchronous input.

2 shows an example of a configuration diagram of a generator protection relay. In Fig. 2, the protection relay is to protect the electric power equipment including the generator when various faults occur. In FIG. 2, GCB denotes a generator breaker, GDS denotes a generator disconnector, T / G denotes a turbine and generator control panel, PT denotes a voltage transformer, CT current transformer, 87G and 87B denote current- Reference numeral 81 denotes a frequency relay, 59/81 denotes an overcurrent relay, 21 denotes a distance relay, 46 denotes a reverse phase relay, 32 denotes a reverse power relay, and 59N denotes a voltage ground relay. There are 87G, 87B relays for general fault protection of breakers and generators, and 59N-1,2,3 relays for earth fault protection. There is 21 relays for protection of 87G / 87B relay in case of loss of function. Various relays are provided for other generators such as voltage, reverse power, field loss, and low frequency. However, the protection system shown in Fig. 2 can not protect the generator asynchronous input failure.

Figure 3 is a fault current flow diagram in the event of an internal generator failure. As shown in FIG. 3, if a short circuit or a ground fault occurs in the generator, the current flows into the fault portion (30 indicates the fault current direction at the generator side failure), and the CT1 and CT8 for the 87G relay all have a current direction of 87G ). 31 indicates the CT secondary current direction at the generator side failure.

As a result, the currents of CT1 and CT8 become the sum current to operate the 87G relay and trip the breaker by using the 87G relay contact to remove the fault from the system. The 87B relays operate in the same way. At this time, 21 relay is also operated but delayed by 2.5sec time delay timer.

4 is a fault current flow chart at the generator asynchronous closing. For example, assuming that the GCB is asynchronous when the generator is fed into the grid, the fault current flows from the grid to the generator neutral point as shown in FIG. 40 indicates the fault current direction at the time of asynchronous charging. At this time, the current (41) of CT1 and CT8 for the 87G relay does not flow into the 87G relay as shown in FIG. 4, and 87B is also the same. Where 41 represents the direction of the CT secondary current during asynchronous charging. 21 relay or 32 relay can be operated but time delay operation is performed and large capacity current is flowed to the generator and transformer and is burned out.

An object of the present invention is to add an asynchronous input protection solution to an existing protection system so as to protect the electric power facility and safely operate the power system even when the generator is asynchronous.

According to the present invention, in a protection device (87, 46, 40, 59N, 59/81, 21, 32 relays, etc.) for protecting a power facility by removing a fault current generated when an equipment failure occurs,

A pulse signal for outputting the output signal only for a predetermined time when the generator operation condition is satisfied;

The overcurrent relay operating signal inherent in the digital protection device;

Is configured as an AND logic signal and its output signal is applied to the lockout relay.

According to the embodiment, the three conditions such as the generator operation condition signal and the NOT logic output signal for NOT logic operation after the delay element for delaying the signal, and the overcurrent relay operation signal may be configured by AND logic.

The final output signal is delayed for one second by the delay element.

Asynchronous input is occasionally caused due to problems such as failure of synchronous relay or connection error in synchronous circuit when the generator system is fed. Once an asynchronous input occurs, the economic loss due to power plant failure and power stoppage, such as tank rupture of the main transformer and burnout of the windings, due to large fault current is large. According to the present invention, even if the generator is charged in the asynchronous state, the generator can be safely operated by quickly removing the fault using the logic configuration of the overcurrent relay output signal and the generator operation condition signal.

The present invention provides a protection device for rapidly protecting a power facility such as a generator and a transformer by quickly breaking a large-capacity fault current generated when an asynchronous generator is input. The most important thing when a generator is introduced into a system after the establishment, extension or other work of a power plant is to close the circuit breaker with the synchronous circuit (voltage phase) exactly matched between the generator and the power system. If the system is fed in the asynchronous state, a large amount of fault current flows from the power system to the generator and the transformer, and the power equipment is destroyed. Actually, asynchronous input causes electric power facilities such as generators and transformers to be burned out occasionally, but there is no protection system that can protect electric power facilities at the time of asynchronous input. In particular, the generation cost of the generator and the transformer is high, but the cost of the power plant itself is considerable. The present invention detects a fault current when a generator asynchronous input is detected and immediately operates the protection system, thereby eliminating a fault and protecting the power equipment, thereby contributing to safe operation of the power system.

The asynchronous input protection according to the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate understanding of the present invention, the prior art will be described in more detail and then the invention will be described.

Figure 5 is an example of a generator protection system logic configuration diagram according to the prior art currently in use. In Fig. 5, reference numerals 87G, 59/81, 46-1, 21, 60, 32 and 59N refer to relays and 86-G refers to lockout relays.

As shown in FIG. 5, the lockout relay 86G is operated to trip the breaker immediately without a time delay in the operation of the relays 87G, 46-1, 40 and 59N. The relay 59/81, 21, , For example, the logic is configured to operate the lockout relay (86G) with a time delay of 59 seconds for 1.2 seconds, 21 seconds for 2.5 seconds, and 32 seconds for 3 seconds.

FIG. 8 shows a waveform actually input to the protective relay in the asynchronous input of the generator. In FIG. 8, reference numeral 80 denotes a fault current waveform at the time of asynchronous generator input, 81 denotes a generator terminal voltage waveform at the time of asynchronous generator input, and 82 denotes operation of the relay. 9, which shows an example of the current waveform at the time of asynchronous input due to the burnout of the synchronous relay, in the state where the voltage phase is not greatly differentiated due to the fault of the synchronous relay, the asynchronous input The fault current is not large and the voltage may be reduced to a small value.

Figure 6 is an implementation logic diagram of an asynchronous input protection solution according to the present invention. 6, a pulse signal for 1 sec, for example, is combined with the AND logic 602 by the instantaneous delay element 601 at which the overcurrent relay output signal and the generator are satisfied with the operating condition And the relay 86G is operated through its output.

As shown in FIG. 5, the conventional logic is constructed by adding an asynchronous input protection solution using an overcurrent relay signal and a synchronous breaker contact. More specifically, the generator asynchronous closing protection solution according to the present invention combines an overcurrent relay pickup signal embedded in the digital protection device and a pulse signal, which is an effective signal of the generator operation condition for 1 sec at the instant of the generator operation condition, by AND logic And the relay 86G is configured to operate through its output.

With this configuration, the overcurrent relay is activated and the generator operation condition is delayed by one second during the asynchronous input of the generator, so that the relay 86G can be operated to remove the fault from the power system.

In general, when the generator is fed into the system, the initial generation amount is within 50% of the generator rating, so the overcurrent relay correction value should be corrected around 120% of the generator rated current considering the site conditions.

Figure 7 is an asynchronous closing protection solution implementation logic diagram in accordance with another aspect of the present invention. More specifically, a signal denoted by reference numeral '70' in FIG. 7 indicates a signal obtained by connecting an overcurrent relay output signal, an output signal when the generator operation condition is satisfied, and a generator operation condition signal with a 1 sec time delay timer and a NOT logic to AND logic And the relay 86G is operated through its output in combination.

Figure 7 shows the same result as the protection solution of Figure 6. In FIG. 6, the pulse signal after the generator operation condition is outputted for 1 sec. In FIG. 7, the pulse signal after the generator operation condition is outputted for 1 sec by combining the 1 sec time delay timer and the NOT logic. The reason for using these two methods is to make it easier to use a protection solution in the field.

1 is a block diagram of a generator synchronization PT circuit;

2 is a block diagram of a generator protection relay.

Figure 3 is a fault current flow diagram in the event of an internal generator failure.

Figure 4 is a fault current flow diagram at generator asynchronous charging.

5 is a block diagram of a generator protection system logic.

6 is a logic diagram of an asynchronous input protection solution implementation according to the present invention.

7 is a logic diagram of another asynchronous input protection solution implementation according to the present invention.

Fig. 8 is an illustration of voltage and current waveforms at the time of asynchronous input by PT circuit erroneous connection; Fig.

Fig. 9 is a diagram showing an example of a current waveform at the time of asynchronous closing due to burnout of a synchronous relay. Fig.

Description of the Related Art

10,11: 345 kV bus PT 12: GIS LCP

13: GCB LCP 14: ECMS

15: Auxiliary PT 16 for voltage adjustment: TCMS

17,18: Generator side PT

60, 70: Generator asynchronous input protection logic

80: Fault current waveform at asynchronous input of generator

81: Generator terminal voltage waveform when asynchronous generator input

82: Operation of 21 relay when asynchronous generator input

601: 1 second pulse timer

602: 1 second time delay timer

Claims (3)

In a protection device (87, 46, 40, 59N, 59/81, 21, 32 relays, etc.) for protecting electric power facilities by eliminating the fault current generated in case of power system equipment failure, A pulse signal for outputting the output signal only for a predetermined time when the generator operation condition is satisfied; The overcurrent relay operating signal inherent in the digital protection device; Is configured as an AND logic signal to apply its output signal to the lockout relay. The generator asynchronous generator according to claim 1, further comprising a delay element for delaying the generator operation condition signal and the operation condition signal, a NOT logic output signal for NOT logic operation, and an overcurrent relay operation signal, Input protection device. 3. The generator asynchronous closing protection device according to claim 1 or 2, wherein the generator is delayed for one second by the delay element.

Images