CN209200656U - A kind of current quick-breaking prevents station with becoming overstepping device in conjunction with zero-sequenceprotection - Google Patents

Abstract

The utility model discloses a combination of current quick-break and zero-sequence protection to prevent substation overvoltage tripping device, which includes a low-voltage circuit breaker and a zero-sequence current protection device. The low-voltage circuit breaker itself is provided with overcurrent protection and voltage loss protection. The zero-sequence current protection device is composed of a zero-sequence current transformer, an overcurrent relay, a time delay relay and a shunt coil. The beneficial effect of the utility model is that: the current quick-break protection can be combined with the zero-sequence protection, and the advantages of the current quick-break protection are simple and reliable, and the characteristics of the sensitivity and quickness of the zero-sequence protection are combined. This device is used for low-voltage power distribution Network and substation power protection can improve the ability to correctly and timely remove the fault area, and avoid the occurrence of skipping trip accidents.

Description

A combination of current quick-break and zero-sequence protection to prevent substation transformer overstepping tripping device

technical field

The utility model relates to a variable-overstepping tripping device, in particular to a variable-overstepping tripping device for a station combined with current quick-break and zero-sequence protection, and belongs to the technical field of relay protection applications.

Background technique

With the improvement of power supply reliability requirements, the problem of system skipping trips has become increasingly prominent, and more than 95% of the skipping trips are caused by line skipping trips. Countermeasures. When a short circuit or other faults occur in primary equipment, because the switch refuses to operate, the protection refuses to operate, or the protection setting does not match, the upper-level switch trips and the current-level switch does not operate, thereby expanding the scope of power outages and the impact of faults. large economic loss. There are several forms of leapfrog tripping: line fault leapfrog, bus fault leapfrog, main transformer fault leapfrog and secondary leapfrog in special cases.

In the low-voltage distribution network, especially in the power distribution network of substations, when a branch circuit breaks down, the branch circuit breaker is often not sensitive enough or the action is not fast enough, failing to cut off the faulty area, causing the upper level protection action, As a result, overstep tripping accidents are caused, the scope of power outages and maintenance scopes are expanded, and the reliability of power supply is reduced. Therefore, a combination of current quick break and zero sequence protection is proposed to prevent substation overstepping tripping devices for the above problems.

Utility model content

The purpose of this utility model is to provide a combination of current quick-break and zero-sequence protection to prevent substation overstepping tripping devices in order to solve the above problems. It not only has the advantages of simple and reliable current quick-break protection, but also has the sensitivity and With the characteristics of quick action, this device is used for the protection of low-voltage distribution network and substation, which can improve the ability of correct and timely removal of fault areas.

The utility model achieves the above-mentioned purpose through the following technical schemes, a combination of current quick-break and zero-sequence protection to prevent sub-level tripping devices for stations, including low-voltage circuit breakers, zero-sequence current transformers, over-current relays and time-delay relays. The over-current relay is arranged between the zero-sequence current transformer and the time-delay relay, and the time-delay relay is arranged between the over-current relay and the low-voltage circuit breaker.

Preferably, an overcurrent relay coil is connected in series in the measuring zero-sequence current loop of the zero-sequence current transformer.

Preferably, the measuring circuit of the zero-sequence current transformer is set to be grounded.

Preferably, the normally open contact of the overcurrent relay is connected in series with the DC coil of the time delay relay, and is driven by a DC power supply.

Preferably, the normally open contact of the time-delay relay is connected in series with the shunt coil of the low-voltage circuit breaker, and is driven by a DC power supply.

The beneficial effect of the utility model compared with the prior art is that the utility model combines the simplicity and reliability of the current quick-break protection with the sensitive and quick action of the zero-sequence protection, effectively improves the ability to discriminate the fault current, quickly removes the fault area, and avoids leapfrog tripping Accidents, and it is easy to cooperate with the upper level zero-sequence protection.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the utility model.

In the figure: 1. Low-voltage circuit breaker; 2. Zero-sequence current transformer; 3. Overcurrent relay; 4. Time-delay relay; 5. Shunt coil.

Detailed ways

The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the implementations. example. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

Please refer to Figure 1, a combination of current quick-break and zero-sequence protection to prevent substation over-level tripping device, including low-voltage circuit breaker 1, zero-sequence current transformer 2, overcurrent relay 3, time delay relay 4 and shunt coil 5. The overcurrent relay 3 is arranged between the zero-sequence current transformer 2 and the time-delay relay 4 , and the time-delay relay 4 is arranged between the overcurrent relay 3 and the shunt coil 5 .

The coil of the overcurrent relay 3 is connected in series in the measuring zero sequence current loop of the zero sequence current transformer 2 . The measurement circuit of the zero-sequence current transformer 2 is set to be grounded. The normally open contact of the overcurrent relay 3 is connected in series with the DC coil of the delay relay 4, and is driven by a DC power supply. The normally open contact of the delay relay 4 is connected in series with the shunt coil 5 of the low voltage circuit breaker 1, and is driven by a DC power supply. The circuit breaker itself has overcurrent and voltage loss protection, but it is not sensitive enough to small current grounding faults. Zero-sequence current protection has the advantages of high sensitivity and quick action. On the basis of traditional single low-voltage circuit breaker protection, a zero-sequence protection device is added to improve the ability to identify fault currents.

As a technical optimization scheme of the utility model, the coil of the overcurrent relay 3 is connected in series with the zero-sequence current measurement circuit, the normally open contact is connected to the positive pole of the DC drive power supply, and then connected in series with the coil of the delay relay 4 and then connected to the power supply negative electrode. Similarly, the normally open contact of the delay relay 4 is connected to the positive pole of the power supply, connected in series with the shunt coil 5 and then connected to the negative pole of the power supply.

In conjunction with specific embodiments, the utility model is further described. In the three-phase cable transmission line, the zero-sequence current transformer 2 is used to obtain the zero-sequence current, and the zero-sequence current loop is connected in series to the coil 3 of the overcurrent relay, and compared with the set value. When the transmission line or branch load fails and the zero-sequence current exceeds the set value, the normally open contact of the overcurrent relay is closed, and the delay relay 4 is powered. After the time is set, the normally open contact of the delay relay Closed, the circuit supplying power to the shunt coil 5 is closed, the shunt coil is energized, the release of the circuit breaker 1 is tripped, and the faulty line is disconnected. The occurrence of leapfrog tripping is avoided, and the reliability of power supply is improved.

It will be apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments are to be considered in all respects as exemplary and not restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description, and it is therefore intended that the All changes within the meaning and range of the required equivalents are embraced within the present invention. Any reference signs in the claims shall not be construed as limiting the involved claim.

In addition, it should be understood that although this specification is described according to implementation modes, not each implementation mode only contains an independent technical solution, and this description in the specification is only for clarity, and those skilled in the art should take the specification as a whole , the technical solutions in the various embodiments can also be properly combined to form other implementations that can be understood by those skilled in the art.

Claims (5)

1. A combination of current quick-break and zero-sequence protection to prevent substation overstepping tripping device, characterized in that it includes a low-voltage circuit breaker (1), zero-sequence current transformer (2), overcurrent relay (3), and time-delay relay (4) and the shunt coil (5), the overcurrent relay (3) is arranged between the zero sequence current transformer (2) and the time delay relay (3), and the time delay relay (4) is arranged between Between the current relay (4) and the shunt coil (5). 2. According to claim 1, a combination of current quick-break and zero-sequence protection prevents the tripping device for substation with variable overstepping, characterized in that: the zero-sequence current transformer (2) is connected in series with an overcurrent relay in the zero-sequence current loop. (3) Coil. 3. A combination of current quick-break and zero-sequence protection according to claim 1, characterized in that the measurement circuit of the zero-sequence current transformer (2) is grounded. 4. According to claim 1, a combination of current quick-break and zero-sequence protection prevents the tripping device of the substation from changing overstepping, characterized in that: the normally open contact of the overcurrent relay (3) and the contact of the delay relay (4) The DC coils are connected in series to set the DC power drive. 5. According to claim 1, a combination of current quick-break and zero-sequence protection prevents the tripping device of the substation from changing over-level, characterized in that: the normally open contact of the delay relay (4) and the low-voltage circuit breaker (1) The shunt coils (5) are connected in series and driven by a DC power supply.