CN117239896A - Dual-power switching control protection device for valve cooling system - Google Patents

Abstract

The application relates to a dual power supply switching control protection device for a valve cooling system, which comprises a control circuit corresponding to each power supply inlet wire, wherein the control circuit is provided with a main branch and a secondary branch; the main branch comprises a control switch and a coil of a first intermediate relay which are connected in series; the auxiliary branch is connected with the coil of the first intermediate relay in parallel, wherein the auxiliary branch comprises a contact of the first intermediate relay, a coil of a power contactor and a current limiting resistor which are connected in series; the current limiting resistor is connected in parallel with a short circuit branch, and the short circuit branch is used for being conducted and disconnected again after being started. The technical scheme of the application can effectively avoid the adhesion of the output contact of the valve cold control device and also effectively avoid the continuous and large-scale heating of the coil of the power contactor, thereby improving the reliability and safety of equipment and power supply.

Description

Dual-power switching control protection device for valve cooling system

Technical Field

The present application relates generally to the field of electrical control technology. More particularly, the present application relates to a dual power switching control protection device for a valve cooling system.

Background

In recent years, the technology of (extra) high-voltage direct-current transmission engineering in China is rapidly developed. In the dc transmission engineering, a converter valve is a core device, and plays a vital role such as ac-dc conversion. For the converter valve, a suitable temperature environment is a necessary condition for safe and stable operation thereof, and therefore the converter valve is provided with a converter valve cooling system (hereinafter referred to as a valve cooling system).

In the prior art, valve cooling systems generally include: the internal cooling electric heater, the external cooling electric heater, the raw water pump, the water supplementing pump, the electric actuator and other devices are generally powered by an alternating current bus in an alternating current power supply cabinet. For example, the air cooler blower is powered by an alternating current bus in the blower power cabinet, and the cooling tower blower, the spray pump, the side filter pump, the drainage pump and other devices are powered by the alternating current bus in the cooling tower power cabinet; once the alternating current power buses are out of order, corresponding equipment cannot normally operate, so that a valve cooling system is stopped, heat dissipation service for a converter valve cannot be continuously provided, and finally the converter valve is stopped, and serious safety operation accidents and economic losses are caused.

In order to ensure the power supply safety of the converter valve, an alternating current power supply of the valve cooling system generally adopts two paths of power supply inlet wires, and the two paths of power supply inlet wires can be automatically switched. For example, when the power supply quality of one power supply inlet wire is in a problem, the power supply of the other power supply inlet wire can be switched. The power supply quality comprises power supply quality information, such as under-voltage, voltage loss, overvoltage and other fault information. And in a normal state, one power supply inlet wire is selected for power supply, and when the fault information is received, a control signal can be output to control the other power supply inlet wire to be switched on.

Specifically, fig. 1 shows a schematic diagram of the electrical principle of the main circuit of the ac power supply. Wherein L1, L2 and L3 represent three-phase alternating current buses, two paths of power supply incoming lines are connected to the three-phase alternating current buses, namely a first power supply incoming line XT1 and a second power supply incoming line XT2, the first power supply incoming line XT1 is connected with a main contact KMN-1 of a first power supply contactor in series, KA1 is an output contact of a valve cold control device and is used for controlling the main contact KMN-1 of the first power supply contactor; similarly, the second power supply incoming line XT2 is connected in series with the main contact KMR-1 of the second power supply contactor, KA2 is the output contact of the valve cold control device and is used for controlling the main contact KMR-1 of the second power supply contactor.

Fig. 2 shows a schematic electrical schematic diagram of a dual power supply switching control circuit according to the prior art.

Wherein SA1 and SB1 represent manual switches, KA1, KB1 and KA2, KB2 represent remote control switches, namely output joints of the valve cold control device. QCN and QCR denote circuit breakers. X1 represents a control power source, which may be taken from an ac bus or obtained by rectifying an ac bus, for example. KMN-2 and KMR-2 represent auxiliary contacts of the power contactor. The circuit shown in fig. 2 includes two loops, each loop corresponds to one power supply incoming line (i.e., a first power supply incoming line and a second power supply incoming line), and contacts and coils of two power supply contactors in each loop are connected in series to form an interlocking circuit, so that only one power supply contactor is ensured to act at the same time.

According to the actual running condition, the dual-power switching control mode has the following technical problems:

1) The control power supply of the first power supply inlet wire and the second power supply inlet wire is taken from the same section of power supply X1, if the section of power supply fails, double power supply switching cannot be realized, any path of alternating current power supply cannot be put into operation, and an alternating current bus loses power, so that the normal operation of valve cooling equipment is affected.

2) In the process of sucking a coil (such as KMN) of a power contactor, short-time overvoltage is generated, impact is generated on a control power supply (such as X1), and the control power supply is likely to be failed after long-term use, so that potential safety hazards exist in the system.

3) The coil (such as KMN) of the power contactor has larger impact current at the suction moment, and the possible impact current can reach more than 10A, and the rated current of the output contact (such as KA 1) of the valve cold control device is generally smaller, and the valve cold control device is operated for a long time or frequently, so that the contact adhesion is easily caused, and further the power switching action cannot be completed, so that the normal operation of the valve cold equipment is influenced.

4) After the action of the power contactor is finished, the coil (such as KMN) of the power contactor is directly connected to the two ends of the control power supply all the time; however, according to the characteristics of the contactor, only a small current is needed to maintain the suction state, and if a large current is maintained for a long time, the coil of the contactor is heated seriously, aging is accelerated, and fire hazards are accompanied.

Based on the above, the application considers optimizing the dual-power switching device, and not only ensures the normal switching function of dual power, but also protects the output contact of the valve cold control device and the coil of the power contactor, thereby avoiding the problems of contact adhesion phenomenon, serious coil heating and the like.

Disclosure of Invention

The application aims to provide a dual-power switching control protection device for a valve cooling system, which is at least used for solving one or more technical problems in the background art.

According to one aspect of the present application, there is provided a dual power supply switching control protection device for a valve cooling system, wherein the valve cooling system comprises two power supply inlet wires, each power supply inlet wire is provided with a main contact of a corresponding power supply contactor, the dual power supply switching control protection device comprises a control circuit corresponding to each power supply inlet wire, wherein the control circuit has a main branch and a sub-branch; the main branch comprises a control switch and a coil (KN 1) of a first intermediate relay connected in series; the auxiliary branch is connected in parallel with the coil (KN 1) of the first intermediate relay, wherein the auxiliary branch comprises contacts (KN 1-1/KN 1-2) of the first intermediate relay, a coil (KWN) of a power contactor and a current limiting resistor (R1) which are connected in series; the current limiting resistor (R1) is connected in parallel with a short-circuit branch, which is used for being conducted and disconnected again after starting.

In one embodiment, a short circuit control branch is further included that controls the short circuit branch.

In one embodiment, the short-circuit branch comprises a contact (KN 2-1) of a second intermediate relay; the short-circuit control branch comprises a coil (KN 2) of a second intermediate relay and an auxiliary contact (KWN-2) of a power contactor connected in series.

In one embodiment, the short-circuit control branch is connected in parallel with the coil (KMN) of the power contactor and in series with the contact (KN 1-1/KN 1-2) of the first intermediate relay.

In one embodiment, the short circuit control branch is connected in parallel with a series circuit portion of a coil (KMN) and a current limiting resistor (R1) of the power contactor.

In one embodiment, wherein the two power supply lines include a first power supply line (XT 1) and a second power supply line (XT 2); the main branch of the control circuit corresponding to the first power supply inlet is connected with a first control power supply (X1), and the main branch of the control circuit corresponding to the second power supply inlet is connected with a second control power supply (X2).

In one embodiment, the contacts of the first intermediate relay are provided with more than two, and the contacts of the more than two first intermediate relays are arranged in series.

In one embodiment, an interlock contact (KWR-3) is also provided in the secondary leg in series with the coil (KWN) of the power contactor.

In one embodiment, the control switch comprises a manual switch and a remote control switch, and the manual switch and the remote control switch are arranged in parallel; the remote control switch comprises a valve cooling control device output contact.

In one embodiment, a circuit breaker is also connected in series in the main branch.

According to the technical scheme, the coil of the power contactor is not directly connected with the output contact of the valve cold control device in series, so that the adhesion of the output contact of the valve cold control device can be effectively avoided, and the safety is improved; according to the application, the current limiting resistor is arranged in the contactor, so that the coil of the power contactor can be effectively prevented from continuously heating in a large amount in the process of maintaining the suction state of the contactor, and the reliability and safety of equipment and a power supply are improved. In addition, the current limiting resistor can reduce the current during starting and protect the coil of the power contactor.

Furthermore, the short circuit control branch circuit is connected with the coil of the power supply contactor in parallel, so that overvoltage generated in the sucking process can be eliminated while normal sucking of the AC power supply main loop contactor is ensured.

Furthermore, the control power supplies corresponding to the first power supply contactor and the second power supply contactor are not the same power supply, so that under extreme conditions, any path of control power supply fails, the double-power switching control protection device can adopt another path of control power supply to operate, one path of incoming line power supply is ensured to be switched on, and normal operation of valve cooling equipment is not influenced.

In summary, the application overcomes a plurality of defects of the original dual-power supply switching circuit through reasonable circuit combination.

Drawings

The above, as well as additional purposes, features, and advantages of exemplary embodiments of the present application will become readily apparent from the following detailed description when read in conjunction with the accompanying drawings. In the drawings, embodiments of the application are illustrated by way of example and not by way of limitation, and like reference numerals refer to similar or corresponding parts and in which:

FIG. 1 is a schematic diagram of the electrical principle of a main circuit powered by an AC power source according to the prior art;

FIG. 2 is a schematic diagram of the electrical principle of a dual power switching control circuit according to the prior art;

fig. 3 is an electrical schematic diagram (first part) of a dual power switching control protection device according to an embodiment of the present application;

fig. 4 is an electrical schematic diagram (second portion) of a dual power switching control protection device according to an embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

The technical solution of the present application is shown in fig. 3 and 4, wherein fig. 3 is used for a first power incoming line XT1 and fig. 4 is used for a second power incoming line XT2. That is, fig. 3 is mainly used to control the main contact KWM-1 of the first power contactor, and fig. 4 is used to control the main contact KWR-1 of the second power contactor, and since the principle of fig. 3 and 4 is basically the same, fig. 3 will be mainly described as an example when describing a circuit. Since the following description mainly refers to fig. 3, the first power contactor is referred to as a power contactor in this embodiment.

Fig. 3 shows a first part of a dual power switching control protection device for a valve cooling system, namely a control circuit corresponding to a first power supply line XT1, wherein the control circuit has a main branch and a secondary branch; the main branch comprises a control switch and a coil KN1 of a first intermediate relay which are connected in series; the auxiliary branch is connected with the coil KN1 of the first intermediate relay in parallel, wherein the auxiliary branch comprises contacts KN1-1/KN1-2 of the first intermediate relay, a coil KWN of a power contactor and a current limiting resistor R1 which are connected in series; wherein the current limiting resistor R1 is connected with a short circuit branch in parallel. The short circuit branch comprises a contact KN2-1 of a second intermediate relay; the short-circuit control branch comprises a coil KN2 of a second intermediate relay and an auxiliary contact KWN-2 of a power contactor which are connected in series.

That is, in the present embodiment, the contact KN2-1 of the second intermediate relay is referred to as a short-circuit branch, and the series circuit of the coil KN2 of the second intermediate relay and the auxiliary contact KWM-2 of the power contactor is referred to as a short-circuit control branch of the short-circuit branch.

The contact KN1-1/KN1-2 of the first intermediate relay is a movable contact, the auxiliary contact KWN-2 of the power contactor is a movable opening contact, and the contact KN2-1 of the second intermediate relay is a movable contact. In one embodiment, the control switch comprises a manual switch SA1 and a remote control switch, and the manual switch and the remote control switch are arranged in parallel; the tele-control switch includes valve cold control device output contacts KA1 and KB1.

The circuit principle of fig. 3 is described below:

under normal conditions, when the manual switch SA1 is closed (or the remote control switch KA1/KB1 is closed), the coil KN1 of the first intermediate relay is electrified, the contacts KN1-1 and KN1-2 of the first intermediate relay are closed (in the embodiment, two series contacts are arranged and play a redundant role), and the current of the auxiliary branch flows through the coil KWN and the current limiting resistor R1 of the power contactor, and the coil KN2 of the second intermediate relay and the auxiliary contact KWN-2 of the power contactor.

At this time (referred to as a first state in this embodiment), since the current limiting resistor R1 is connected in series, the current on the coil KWN of the power contactor is small at this time, and at the same time, the auxiliary contact KWN-2 of the power contactor does not operate and is thrown to maintain a closed state because the current on the coil KWN of the power contactor is small. That is, upon actuation, the current on coil KWN of the power contactor is not small enough to actuate the corresponding contacts.

Immediately (in this embodiment referred to as the second state), since the coil KN2 of the second intermediate relay in the short-circuit control branch is energized, the contact KN2-1 of the second intermediate relay is energized, and the short-circuit branch is thus turned on to short-circuit the current limiting resistor R1, so that the current on the coil KWN of the power contactor increases, and finally the main contact KWN-1 of the power contactor on the first power supply line X1 is energized, and the first power supply line XT1 powers the system.

Then (in this embodiment referred to as the third state), when the main contact KWN-1 of the power contactor is sucked, the auxiliary contact KWN-2 of the power contactor is opened, and the short-circuit control branch is opened, so that the coil KN2 of the second intermediate relay is deenergized, and therefore, the contact KN2-1 of the second intermediate relay is opened, so that the current-limiting resistor R1 is put into the auxiliary branch again.

According to the circuit principle, the impact on the coil KWN of the power contactor is reduced due to the existence of the first state, and the short circuit control branch is connected with the coil KWN of the power contactor and the circuit part of the current limiting resistor R1 in parallel, so that overvoltage on the coil KWN of the power contactor is limited, the coil KWN of the power contactor and a control power supply are protected, the service life of the power contactor can be prolonged, and potential safety hazards are reduced.

In the second state, the current limiting resistor R1 is shorted, so that sufficient current can be supplied to enable normal operation of the main contact KWN-1 of the power contactor.

Because the current required by the power contactor in the stable state is smaller (compared with the state when the power contactor is required to act), in the third state, the current limiting resistor R1 is put into the auxiliary branch again, so that the current flowing through the coil KWN of the power contactor in the stable state is restrained, the situation that the larger current is kept on the coil KWN of the power contactor for a long time is avoided, and the potential safety hazard is reduced.

Moreover, in this embodiment, the remote control switch KA1/KB1 may be an output contact of the valve cold control device, and the manual switch SA1 and the remote control switch KA1/KB1 are in a parallel connection relationship with the coil KMN of the power contactor, so that the impact current of the power contactor at the suction moment will not greatly affect the output contact of the valve cold control device, thereby prolonging the service life of the output contact of the valve cold control device and reducing the failure probability.

In this embodiment, as shown in fig. 3, the short-circuit control branch is connected in parallel with the series circuit portion of the coil KMN and the current limiting resistor R1 of the power contactor. In other embodiments, the short-circuit control branch may also be connected in parallel with the coil KMN of the power contactor and in series with the contacts KN1-1/KN1-2 of the first intermediate relay, thereby ensuring that the short-circuit control branch can be controlled by the contacts of the first intermediate relay.

As an example, the short-circuit control branch can be connected directly in parallel with the winding KMN of the power contactor, in which case the current-limiting resistor R1 can also limit the current flowing through the winding KMN of the power contactor in the first state, and in the second state the short-circuit branch can short-circuit the current-limiting resistor R1, in which case the current flowing through the winding KMN of the power contactor is smaller due to the shunting of the short-circuit control branch.

Referring to fig. 1, 3 and 4, in one embodiment, the two power supply lines of the system include a first power supply line XT1 and a second power supply line XT2; the main branch of the control circuit corresponding to the first power inlet wire is connected with a first control power supply X1, and the main branch of the control circuit corresponding to the second power inlet wire is connected with a second control power supply X2. That is, the first control power source X1 and the second control power source X2 are not the same power source, for example, the first control power source X1 and the second control power source X2 may be respectively from different ac buses, so in an extreme case, any path of control power source fails, the dual-power switching control protection device may use another path of control power source to operate, and it is ensured that there is a path of power source incoming line input, and normal operation of the valve cooling device is not affected.

The circuit shown in fig. 4 corresponds exactly to the circuit shown in fig. 3, for example, with a third intermediate relay (e.g., KR 1) having the same function as the first intermediate relay, a fourth intermediate relay (e.g., KR 2) having the same function as the second intermediate relay, and a second power contactor (e.g., KMR) corresponding to the first power contactor (e.g., KMN). The control switch in fig. 4 includes a manual switch SA2 and valve cold control device output contacts KA2 and KB2. The structure and operation principle of the circuit shown in fig. 4 are substantially the same as those of fig. 3, and thus are not described herein.

With reference to fig. 3 and 4, the secondary branch shown in fig. 3 is further provided with an interlocking contact KWR-3 of a second power contactor connected in series with the coil KWN of the first power contactor; the secondary leg shown in fig. 4 is also provided with an interlock contact kw n-3 of the first power supply contactor in series with the coil KWR of the second power supply contactor. This interlocking design ensures that only one power contact will be active at a time.

It should be understood that when the terms "first," "second," "third," and "fourth," etc. are used in the claims, the specification and the drawings of the present application, they are used merely for distinguishing between different objects and not for describing a particular sequential order. The terms "comprises" and "comprising" when used in the specification and claims of the present application are taken to specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It is also to be understood that the terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the specification and claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should be further understood that the term "and/or" as used in the present specification and claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.

As used in this specification and the claims, the term "if" may be interpreted as "when..once" or "in response to a determination" or "in response to detection" depending on the context. Similarly, the phrase "if a determination" or "if a [ described condition or event ] is detected" may be interpreted in the context of meaning "upon determination" or "in response to determination" or "upon detection of a [ described condition or event ]" or "in response to detection of a [ described condition or event ]".

Although the embodiments of the present application are described above, the descriptions are merely examples for facilitating understanding of the present application, and are not intended to limit the scope and application of the present application. Any person skilled in the art can make any modification and variation in form and detail without departing from the spirit and scope of the present disclosure, but the scope of the present disclosure is defined by the appended claims.

Claims (10)

1. The double-power supply switching control protection device for the valve cooling system comprises two paths of power supply inlet wires, wherein each path of power supply inlet wire is provided with a main contact of a corresponding power supply contactor,

the dual-power switching control protection device comprises a control circuit corresponding to each power inlet wire, wherein the control circuit is provided with a main branch and a secondary branch;

the main branch comprises a control switch and a coil (KN 1) of a first intermediate relay connected in series;

the auxiliary branch is connected in parallel with the coil (KN 1) of the first intermediate relay, wherein the auxiliary branch comprises contacts (KN 1-1/KN 1-2) of the first intermediate relay, a coil (KWN) of a power contactor and a current limiting resistor (R1) which are connected in series; the current limiting resistor (R1) is connected in parallel with a short-circuit branch, which is used for being conducted and disconnected again after starting.

2. The dual power switching control protector for a valve cooling system of claim 1, further comprising a short circuit control branch controlling said short circuit branch.

3. A dual power switching control protector for valve cooling system according to claim 2, characterized in that the short circuit branch comprises the contact (KN 2-1) of the second intermediate relay; the short-circuit control branch comprises a coil (KN 2) of a second intermediate relay and an auxiliary contact (KWN-2) of a power contactor connected in series.

4. A dual power supply switching control protector for a valve cooling system according to claim 3, characterized in that the short circuit control branch is connected in parallel with the coil (KMN) of the power contactor and in series with the contact (KN 1-1/KN 1-2) of the first intermediate relay.

5. A dual power switching control protector for a valve cooling system according to claim 3, characterized in that the short circuit control branch is connected in parallel with the series circuit part of the coil (KMN) and the current limiting resistor (R1) of the power contactor.

6. A dual power switching control protector for valve cooling system according to claim 1 wherein said two power supply lines comprise a first power supply line (XT 1) and a second power supply line (XT 2);

the main branch of the control circuit corresponding to the first power supply inlet is connected with a first control power supply (X1), and the main branch of the control circuit corresponding to the second power supply inlet is connected with a second control power supply (X2).

7. The dual power switching control protector for a valve cooling system according to claim 1, wherein the contacts of the first intermediate relay are provided in two or more, and the contacts of the first intermediate relay are provided in series.

8. A dual power switching control protector for a valve cooling system according to any one of claims 1 to 7 wherein an interlock contact (KWR-3) in series with the coil (KWN) of the power contactor is also provided in the secondary branch.

9. The dual power switching control protector for a valve cooling system as claimed in claim 8, wherein said control switch comprises a manual switch and a remote control switch, the manual switch and the remote control switch being arranged in parallel; the remote control switch comprises a valve cooling control device output contact.

10. The dual power switching control protector for a valve cooling system of claim 9, wherein a circuit breaker is further connected in series in said main branch.