Medium-pressure stable quick cutting device

Abstract

The utility model belongs to the technical field of medium-voltage power supply, and particularly relates to a medium-voltage stable quick switching device, which comprises a stand-by power supply self-input device connected with an I-section wire inlet cabinet, an II-section wire inlet cabinet and a sectionalized cabinet used for connecting an I-section bus with an II-section bus. The stand-by power supply self-switching device is connected with the motor feed-out cabinets on the I-section bus and the II-section bus through the intermediate relay and is connected with the motor restarting device; and the motor restarting device is connected with the motor feed-out cabinets on the I-section bus and the II-section bus. Compared with the prior art, the quick switching device has the beneficial effects that the quick switching device can solve the problem brought to stable operation of a medium-voltage power supply network of a petrochemical enterprise when a power grid of the enterprise fails or operates abnormally and the quick switching device enters a third input mode, so that stable switching of a power supply is realized; and secondly, a motor restarting device is utilized to avoid collapse of a power supply system and meet the requirement of continuous operation of a process pump motor of a petrochemical enterprise.

Description

Technical Field

[0001] The utility model belongs to the technical field of medium voltage power supply, and in particular relates to a medium voltage stable fast switching device. Background Art

[0002] In petrochemical enterprises, it is common to see abnormal power outages or short-term power outages (commonly known as "power fluctuations") caused by failures or abnormal operation of external or internal power supply networks. Due to the particularity of the process flow of petrochemical enterprises, power outages or abnormal operation often cause process equipment to be shut down or run idle, process flow to be interrupted or products to be scrapped, and sometimes even serious consequences such as scrapping of process equipment.

[0003] At present, the method for industrial enterprises to solve the problem of medium-voltage power supply reliability is to set up single busbar segmented wiring, two-way power supply, and install a quick-cut device in the segmented switch cabinet. The quick-cut device is a kind of automatic input device for the backup power supply of the power system; after the quick-cut device is started, there are three types of input forms for the backup power supply: the first input form is synchronous input (suitable for manual gate operation), the second input form is the first cycle input, and the third input form is the residual voltage input mode. The first cycle input mode and the residual voltage input mode are suitable for power grid accidents and can realize automatic switching.

[0004] For general enterprises, the three input modes of the quick-cut device have met the power supply requirements. However, one of the load characteristics of petrochemical enterprises is that the motor load accounts for a large proportion (the calculated capacity of the motor accounts for about 80% or more of the total calculated capacity of the factory), and continuous operation is required. When the power is interrupted or short-term power outage occurs, and the quick-cut device enters the third input mode, the faulty power supply is cut off and the normal power supply is input. At this time, there are many motors on the faulty bus that need to be restarted, causing the starting current to be too large, which will cause the voltage of the normal bus to drop suddenly, and then cause the motor on the normal bus to operate abnormally, shut down, and even cause the power supply system to collapse. To solve this problem, enterprises need to limit the capacity of the restarted motor to avoid the collapse of the power supply system and ensure that the continuity of the process is not affected. Utility Model Content

[0005] In order to solve the technical problem that the power supply system is prone to collapse when switching power sources, the utility model provides a medium voltage stable fast switching device.

[0006] The purpose of the utility model is to be achieved by adopting the following technical scheme. A medium voltage stable fast switching device proposed in the utility model includes a standby power supply self-starting device connected to the I-section incoming line cabinet, the II-section incoming line cabinet, and the sectional cabinet, the sectional cabinet is used to connect the I-section bus and the II-section bus, the standby power supply self-starting device is connected to each motor feeder cabinet on the I-section bus and the II-section bus through an intermediate relay and is connected to the motor restarting device, and the motor restarting device is connected to the motor feeder cabinet on the I-section bus and the II-section bus.

[0007] Furthermore, the backup power supply automatic switching device is a common backup power supply automatic switching device or a quick-cut device.

[0008] Furthermore, the backup power supply self-starting device is arranged in the segmented cabinet.

[0009] Furthermore, PT cabinets are provided on both the bus section I and the bus section II.

[0010] Compared with the prior art, the utility model is beneficial in that:

[0011] The device of the utility model can solve the problem of stable operation of the medium-voltage power supply network of the petrochemical enterprise caused by enterprise power grid failure or abnormal operation when the quick-cut device enters the third input mode, and realize stable switching of power supply; secondly, the motor restart device is used to avoid power supply system collapse, solving the need for continuous operation of the process machine pump motor of the petrochemical enterprise.

[0012] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the utility model more obvious and easy to understand, the following preferred embodiments are specifically cited and described in detail with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of an embodiment of a medium-voltage stable quick-cut device of the utility model.

[0014] [Reference Signs]

[0015] 1- quick-cut device, 2- section I incoming line cabinet, 3- section II incoming line cabinet, 4- section cabinet, 5- PT cabinet, 6- motor feed cabinet, 7- intermediate relay, 8- motor restart device. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0017] The utility model is a medium voltage stable quick-cut device embodiment, as shown in Figure 1 As shown, the device is used in the power supply system of petrochemical enterprises.

[0018] In this embodiment, the power supply system includes two bus sections of a substation, the two bus sections are bus section I and bus section II, the voltage of both bus sections is 10kV, and both bus sections are connected to 10kV motor loads and other loads.

[0019] Each section of the bus is connected to an incoming line cabinet (section I incoming line cabinet 2 or section II incoming line cabinet 3, used to connect to the corresponding section I power incoming line and section II power incoming line), a PT cabinet 5 (section I PT cabinet or section II PT cabinet) and several motor feeder cabinets 6 and other feeder cabinets. The motor feeder cabinet is used to control the motor of the corresponding process machine pump; the section I bus and the section II bus are connected through a segmentation cabinet 4, and the quick-cut device 1 is connected to the two incoming line cabinets and the segmentation cabinet 4 to realize signal collection. The quick-cut device 1 sends a signal to the incoming line cabinet and the segmentation cabinet 4 according to the collected status of the section I power incoming line and the section II power incoming line. The incoming line cabinet and the segmentation cabinet 4 open or close the switches therein according to the signal.

[0020] When one of the power supplies fails, the quick-cut device can detect the fault, cut off the incoming line cabinet corresponding to the power supply, and connect the segment cabinet 4, so that all loads are powered by another power supply. The switching device 1 is a quick-cut device in the existing power supply system, usually a controller, which can send pulse signals. The quick-cut device 1 is connected to the intermediate relay 7, and the intermediate relay 7 is connected to each motor feed cabinet 6. The pulse signal sent by the quick-cut device 1 is extended through the intermediate relay 7. The extended node is connected to the tripping circuit of the motor feed cabinet 6 that needs to trip, so as to realize the tripping of the motor circuit and interrupt the power supply of the corresponding motor.

[0021] The quick-cut device 1 is also connected to the motor restart device 8, which is connected to each motor feeder cabinet. The motor restart device 8 sends a motor start pulse signal to the closing circuit of the motor feeder cabinet that needs to be restarted, completes the closing of the corresponding motor circuit, and realizes the starting of the corresponding motor. When starting each motor, start each motor on the faulty bus in sequence to avoid excessive impact current, thereby avoiding a sudden drop in the normal bus voltage.

[0022] After the fast-cut device 1 detects that the busbar is de-energized and enters the residual voltage input mode, it sends out a pulse signal and trips the feeding motor circuit on the de-energized busbar through the intermediate relay 7. After the switching is completed and the voltage of the de-energized busbar is restored to stability, the motor restart device 8 sends out motor start pulse signals in sequence according to the busbar voltage, power supply current, motor parameters, and motor operating status (tripping) detected by the fast-cut device 1, and then starts the motors that need to be started in sequence.

[0023] Take the example of bus section I losing power and bus section II having power. When the power supply line of section I fails, the quick-cut device 1 starts to prepare for the first cycle input. When the conditions for the first cycle input mode are met, the quick-cut device 1 controls the section I incoming cabinet 2 to trip and the sectionalizing cabinet 4 to close, so that the section II power supply supplies all loads. If the quick-cut device 1 fails to detect the first cycle signal or the input mode fails, the quick-cut device 1 enters the residual pressure input mode.

[0024] The conditions for the residual pressure input mode are non-internal fault and non-manual operation; after the above conditions are met, the switching is completed through the coordination of the upper and lower levels. During this period, the number of medium-voltage motors in general enterprises is limited, and the motor does not need to be tripped when it is restarted. After the sectionalizing cabinet 4 is closed, the II section incoming power supply carries all the loads. However, there are many motors in petrochemical enterprises. If the fast-cut device 1 puts the II section power supply into the I section bus at this time, it may cause excessive impact current and a sudden drop in the voltage of the II section bus. The utility model is that when the fast-cut device 1 enters the residual pressure switching mode, a pulse signal is sent out, and after being processed and expanded by the intermediate relay 7, some motors that need to be restarted (motor of important process machine pumps) are first tripped from the fault bus, so that the corresponding motor is disconnected from the fault bus, reducing the impact of the starting current of the restarted motor group on the normal bus, ensuring the reliability of the power supply network, and making the impact current of the restarted motor group within the allowable range of the II section power supply. After the motor trips, the fast-cut device 1 realizes the residual pressure switching, and the II section power supply is put into the I section bus.

[0025] After the voltage of the de-energized bus is stabilized, the process machine pump motors that need to be started are started in sequence through the motor restart device 8, so that the concentrated current impact of the restart motor cluster starting in a centralized manner is converted into a dispersed impact current of each motor being started at intervals.

[0026] If a common standby power self-initiating device (common BZT device for short) is installed on the sectionalizing cabinet 4 to replace the quick-cutting device 1, the common BZT device sends the motor trip pulse signal; when the bus fails and loses power, the common BZT device sends a pulse signal to the intermediate relay 7, which is then expanded to send a trip pulse signal to the motor feeder cabinet 6 on the faulty bus to achieve tripping, and then the same operation process as the quick-cutting device 1 is adopted to start each motor in turn. The common BZT device is manually operated, while the quick-cutting device 1 is automatically operated.

[0027] In this embodiment, the quick-cut device 1 may be disposed in the segment cabinet 4 .

[0028] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A medium voltage stable fast switching device, comprising a standby power supply automatic input device connected to the I section incoming line cabinet, the II section incoming line cabinet, and the sectional cabinet, the sectional cabinet is used to connect the I section busbar and the II section busbar, characterized in that: The standby power supply self-starting device is connected to each motor feeder cabinet on the I-section bus and the II-section bus through an intermediate relay and is connected to the motor restarting device, and the motor restarting device is connected to the motor feeder cabinet on the I-section bus and the II-section bus.

2. A medium voltage stable quick-cut device according to claim 1, characterized in that: The standby power supply automatic switching device is a common standby power supply automatic switching device or a quick switching device.

3. A medium voltage stable quick-cut device according to claim 1 or 2, characterized in that: The standby power supply self-starting device is arranged in the segment cabinet.

4. A medium voltage stable quick-cut device according to claim 1, characterized in that: PT cabinets are provided on the busbar section I and busbar section II.

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