Low-voltage power distribution system of sewage treatment plant

Abstract

A low-voltage power distribution system of a sewage treatment plant comprises a transformer and a bus, the high-voltage side of the transformer is connected with an external power grid, the low-voltage side of the transformer is connected with a wire inlet main switch, and a neutral point is directly grounded through a grounding wire; the wire outlet end of the wire inlet main switch is connected with a bus; a total surge protector loop, a reactive compensation loop and a low-voltage switch cabinet loop are connected to a bus in parallel, a plurality of load loops are arranged in the low-voltage switch cabinet loop, the reactive compensation loop comprises a control loop and a plurality of reactive compensation branch loops, reactive compensation capacitor banks are arranged in the reactive compensation branch loops, and the reactive compensation capacitor banks are connected with the low-voltage switch cabinet loop. According to the utility model, a 660V power supply voltage is added, so that the power supply capability of a low-voltage power grid of a sewage treatment plant is powerfully enhanced, the line loss and the transformer loss in the system operation process are reduced, and the operation management cost of the sewage treatment plant is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to electrical voltage control technical field, especially, relate to a sewage treatment plant low voltage distribution system. BACKGROUND

[0002] The commonly used power supply and distribution mode of the existing sewage treatment plant is to combine 10kV or 6kV medium voltage and 380V low voltage to supply power to the sewage plant equipment. With the expansion of the sewage treatment plant, the number of equipment is increasing, the single machine power is increasing, and the layout is more and more dispersed. The traditional power supply and distribution mode is more and more difficult to adapt to the changes of the sewage treatment plant. That is, the 380V voltage used has too large distribution current, resulting in large line investment and large operation loss, and often causes power supply difficulties due to long line. Although the 10kV medium voltage has small distribution current, it is not safe due to high voltage. In addition, the investment and operation cost of 10kV equipment is high, which cannot well meet the power supply and distribution mode of the sewage treatment plant.

[0003] In the field of coal mines and smelting, 660V low voltage distribution system has been used for a long time to avoid the above problems. However, in other industrial fields, especially in sewage treatment plants, 660V distribution is rarely used. The reason for not using 660V distribution is that the factory area is used to the original distribution mode, and is unfamiliar with 660V distribution. There are few engineering examples that can be used as reference for existing 660V distribution design. Manual data and product selection are also lacking. Because the environment of coal mine is special, the technical scheme of 660V distribution system may not be suitable for conventional industrial enterprises on the ground. CONTENT OF THE UTILITY MODEL

[0004] In order to solve the problems of high line loss and power supply difficulty caused by using 380V low voltage in traditional power supply and distribution of sewage treatment plant, and the problems of insecurity and high investment and operation cost caused by using 10kV medium voltage, 660V low voltage distribution is used to solve the above defects. However, because there are few existing 660V distribution design schemes, it is difficult to directly transplant the 660V distribution design of coal mine to provide for the use of conventional industrial enterprises. The utility model provides a sewage treatment plant low voltage distribution system, which increases the 660V power supply voltage, and enhances the power supply capacity of the low voltage power grid of the sewage treatment plant. The utility model is realized by the following technical scheme:

[0005] A sewage treatment plant low voltage distribution system, comprising a transformer and a bus bar, the high voltage side of the transformer is connected to an external power grid, the low voltage side of the transformer is connected to the incoming line end of an incoming line total switch, and the neutral point of the transformer needs to be directly grounded through a grounding wire; the outgoing line end of the incoming line total switch is connected to the bus bar, and a group of incoming line current transformers are arranged between the outgoing line end of the incoming line total switch and the bus bar.

[0006] The total bus bar is connected in parallel with a total surge protector circuit, a reactive power compensation circuit and a low-voltage switch cabinet circuit, the low-voltage switch cabinet circuit is provided with a plurality of load circuits, the reactive power compensation circuit comprises a control circuit and a plurality of reactive power compensation sub-circuits, the reactive power compensation sub-circuit is provided with a reactive power compensation capacitor bank, and the reactive power compensation capacitors in the reactive power compensation capacitor bank are connected with each other in star connection.

[0007] Preferably, the total surge protector circuit comprises a total surge circuit breaker and a total surge protector, the incoming line end of the total surge circuit breaker is directly connected with the total bus bar, the outgoing line end of the total surge circuit breaker is connected with the total surge protector, and the total surge protector is directly grounded through a grounding wire.

[0008] Preferably, the control circuit is provided with a reactive power compensation circuit multi-channel controller, and the reactive power compensation circuit multi-channel controller is used for controlling the plurality of reactive power compensation sub-circuits.

[0009] Preferably, the reactive power compensation circuit further comprises a reactive power compensation circuit bus bar, and the reactive power compensation circuit bus bar is further provided with a reactive power compensation circuit disconnector and a reactive power compensation circuit circuit breaker between the reactive power compensation circuit bus bar and the total bus bar.

[0010] Preferably, the incoming line end of the reactive power compensation circuit disconnector is connected with the total bus bar, the outgoing line end of the reactive power compensation circuit disconnector is connected with the incoming line end of the reactive power compensation circuit circuit breaker, the outgoing line end of the reactive power compensation circuit circuit breaker is directly connected with the reactive power compensation circuit bus bar, and a group of reactive power compensation circuit current transformers are further arranged between the outgoing line end of the reactive power compensation circuit circuit breaker and the reactive power compensation circuit bus bar.

[0011] Preferably, a plurality of reactive power compensation sub-circuits and a group of reactive power compensation circuit surge protectors are connected in parallel on the reactive power compensation circuit bus bar, and the reactive power compensation circuit surge protectors need to be directly grounded through a grounding wire.

[0012] Preferably, the reactive power compensation sub-circuit comprises a fuse, one end of the fuse is directly connected with the reactive power compensation circuit bus bar, the other end of the fuse is connected with a reactive power compensation contactor, the other end of the reactive power compensation contactor is connected with one end of a reactor, and the other end of the reactor is connected with a reactive power compensation capacitor bank.

[0013] Preferably, the load circuit comprises a load circuit circuit breaker, the incoming line end of the load circuit circuit breaker is directly connected with the total bus bar, the outgoing line end of the load circuit circuit breaker is directly connected with a load, and a group of load circuit current transformers are further arranged between the outgoing line end of the load circuit circuit breaker and the load; or,

[0014] The outgoing terminal of the load circuit breaker is connected with one end of a load circuit contactor, the other end of the load circuit contactor is connected with a thermal relay, and the other end of the thermal relay is connected with a load.

[0015] Preferably, the transformer is a 660V voltage grade transformer, the bus bar is a 660V voltage grade bus bar, the external power grid is a 10kV or 35kV voltage grade power grid, the incoming line total switch and the incoming line current transformer are 660V voltage grade, and the total surge protector circuit, the reactive compensation circuit and the low-voltage switch cabinet circuit are 660V voltage grade.

[0016] The utility model discloses a beneficial effect:

[0017] Compared with the prior art, the utility model discloses a power supply voltage of 660V is added, which effectively enhances the power supply capacity of the low-voltage power grid of the sewage treatment plant, the sewage treatment plant saves the equipment material purchase cost and engineering installation cost of the sewage treatment plant by adopting the 660V low-voltage distribution system, reduces the line loss and transformer loss in the system operation process, and reduces the operation and management cost of the sewage treatment plant. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The utility model discloses a low-voltage distribution system circuit principle diagram.

[0019] In the drawing: 1, transformer;2, incoming line total switch;3, incoming line current transformer;4, total surge circuit breaker;5, total surge protector;6, bus bar;7, reactive compensation circuit isolating switch;8, reactive compensation circuit breaker;9, reactive compensation circuit current transformer;10, reactive compensation circuit surge protector;11, fuse;12, electric reactor;13, reactive compensation capacitor;14, load circuit breaker;15, load circuit current transformer;16, thermal relay;17, reactive compensation circuit bus bar;18, load circuit contactor, 19, reactive compensation contactor. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the utility model, the utility model will be described more fully below with reference to the relevant drawings. The preferred embodiments of the utility model are given in the drawings, but the utility model can be realized in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the utility model more thorough and comprehensive.

[0021] Next, the utility model will be further described in combination with the drawings and specific embodiments:

[0022] Embodiment 1:

[0023] As Figure 1As shown, a sewage treatment plant low-voltage power distribution system includes a transformer and a bus bus, using the high-voltage side of the transformer to connect the external power grid, so that the power of the external power grid is transmitted into the internal power distribution system, the transformer can convert the high-voltage power delivered by the external power grid into low-voltage power required by the equipment, the voltage level of the high-voltage side of the transformer is consistent with the voltage level of the external power grid, and the voltage level of the low-voltage side is consistent with the voltage level of the power distribution system of the sewage treatment plant, and the neutral point of the transformer needs to be directly grounded through the grounding wire. Continue to connect the low-voltage side of the transformer with the incoming line end of the incoming line main switch, and then connect the outgoing line end of the incoming line main switch with the bus bus, so that the bus bus becomes the main power supply carrier. A set of incoming line current transformers are also provided between the outgoing line end of the incoming line main switch and the bus bus, the purpose is to use a set of coils to induce the current of the conductor by electromagnetic induction, and the incoming line current transformer is not directly connected with the power transmission loop. When installing, only the conductor conveying current needs to pass through the coil of the current transformer.

[0024] Among them, the total surge protector loop, the reactive power compensation loop and the low-voltage switch cabinet loop are connected in parallel on the bus bus to realize parallel power supply for the three; the transformer used in the utility model is a 660V voltage level transformer, and the voltage level of the external power grid is 10kV or 35kV; when the voltage level of the external power grid is 10kV, a 10kV to 660V transformer is used, and similarly, a 35kV to 660V transformer is used; therefore, the voltage levels of the low-voltage bus, the incoming line main switch and the incoming line current transformer are also 660V. Since the total surge protector loop, the reactive power compensation loop and the low-voltage switch cabinet loop are connected in parallel to the bus bus, the voltage levels are also 660V. In order to reduce the short-circuit current of the 660V low-voltage power distribution system, the impedance of the 660V transformer should be appropriately increased.

[0025] The total surge protector loop includes a total surge circuit breaker and a total surge protector, wherein the incoming line end of the total surge circuit breaker is directly connected with the bus bus, the outgoing line end of the total surge circuit breaker is connected with the total surge protector, and finally the total surge protector is directly grounded through the grounding wire.

[0026] The reactive power compensation loop includes a control loop and a plurality of reactive power compensation sub-loops; wherein the control loop is provided with a reactive power compensation loop multi-channel controller, and the reactive power compensation loop multi-channel controller is used to control the operation of the reactive power compensation sub-loop. Specifically, the control loop is a separate operation line, which operates independently of the reactive power compensation loop and does not conflict with each other. The reactive power compensation loop multi-channel controller provided in the control loop is only used to control the plurality of reactive power compensation sub-loops. That is, when there are three reactive power compensation sub-loops, a reactive power compensation loop multi-channel controller capable of achieving three independent controls is used. When there are six reactive power compensation sub-loops, a reactive power compensation loop multi-channel controller capable of achieving six independent controls is used.

[0027] The reactive compensation loop system further comprises a reactive compensation loop bus, and a reactive compensation loop disconnector and a reactive compensation loop circuit breaker are further arranged between the reactive compensation loop bus and the bus bar, specifically, the incoming line end of the reactive compensation loop disconnector is connected with the bus bar, the outgoing line end thereof is connected with the incoming line end of the reactive compensation loop circuit breaker, and the outgoing line end of the reactive compensation loop circuit breaker is directly connected with the reactive compensation loop bus, and a set of reactive compensation loop current transformers are also arranged between the outgoing line end of the reactive compensation loop circuit breaker and the reactive compensation loop bus, which are also used for sensing the current of the conductive body and have the same connection principle as the incoming line current transformers.

[0028] A plurality of reactive compensation sub-loops and a set of reactive compensation surge protectors are further connected in parallel on the reactive compensation loop bus, the reactive compensation surge protectors are directly grounded through grounding wires, and a reactive compensation capacitor bank is further arranged in the reactive compensation sub-loop, and the reactive compensation capacitors in the reactive compensation capacitor bank need to be connected with each other in star connection. Each set of reactive compensation sub-loops comprises a fuse, one end of the fuse is directly connected with the reactive compensation loop bus, the other end is connected with a reactive compensation contactor, the other end of the reactive compensation contactor is connected with one end of a reactor, and the reactor is connected with the reactive compensation capacitor bank. The reactive compensation loop used in the utility model is preferably designed to have 6 reactive compensation sub-loops, each of which can realize 50kVar of reactive compensation, and the total compensation capacity can reach 300kVar.

[0029] The low-voltage switch cabinet loop is provided with a plurality of load loops, including a load loop 1, a load loop 2, …, a load loop N, N is a natural number greater than 2, the number of specific load loops can be configured according to the configuration in the station, each load loop comprises a load loop circuit breaker, the incoming line end of the load loop circuit breaker is directly connected with the bus bar, and the outgoing line end is directly connected with a load, and a set of load loop current transformers are arranged between the outgoing line end of the load loop circuit breaker and the load for sensing the current, the load connected below can be a 200-400kVA transformer, which realizes the supply of 220V or 380V voltage in the station; or the outgoing line end of the load loop circuit breaker is connected with one end of a load loop contactor, the other end is connected with a thermal relay, and the other end of the thermal relay is connected with a motor load, the motor load can be an AC motor with a power of 30-90kw, specifically an AC motor used for driving a fan, a water pump and other power equipment in a sewage treatment plant.

[0030] The low-voltage power distribution system of the utility model is also equipped with a grounding system, which is divided into working grounding, lightning protection grounding and protection grounding. The exposed conductive parts of the neutral point of the power system and electrical equipment and devices are connected to the ground through a conductor, which is an important measure to ensure system operation and protect personal and equipment safety. The specific grounding condition can be set according to the actual device of the low-voltage power distribution system. Since the low-voltage power distribution system of the utility model is suitable for sewage treatment plants, the 660V power distribution adopts a neutral point direct grounding mode, which is different from the 660V power distribution system of coal mine plants. When a single-phase grounding fault occurs in the neutral point direct grounding mode, the grounding current is large. The 660V power distribution system of coal mine plants cannot adopt this mode because the large current is easy to cause underground fire or gas explosion, but the sewage treatment plant does not have this hidden danger. A large grounding current can make the circuit breaker act immediately to cut off the fault circuit.

[0031] For those skilled in the art, various corresponding changes and modifications can be made to the above-described technical solutions and concepts, and all such changes and modifications should be within the scope of protection of the utility model claim.

Claims

1. A low voltage distribution system for a sewage treatment plant comprising transformers and a busbar, characterised in that, The high-voltage side of the transformer is connected with an external power grid, the low-voltage side of the transformer is connected with the incoming line end of an incoming line general switch, and the neutral point of the transformer needs to be directly grounded through a grounding wire; the outgoing line end of the incoming line general switch is connected with a busbar, and a group of incoming line current transformers are further arranged between the outgoing line end of the incoming line general switch and the busbar; The busbar is connected in parallel with a total surge protector loop, a reactive power compensation loop and a low-voltage switch cabinet loop, a plurality of load loops are arranged in the low-voltage switch cabinet loop, the reactive power compensation loop comprises a control loop and a plurality of reactive power compensation sub-loops, and reactive power compensation capacitors in the reactive power compensation capacitor group are connected with each other in a star connection mode.

2. A low voltage distribution system for a sewage treatment plant according to claim 1, wherein, The total surge protector loop comprises a total surge circuit breaker and a total surge protector, the incoming line end of the total surge circuit breaker is directly connected with the busbar, the outgoing line end of the total surge circuit breaker is connected with the total surge protector, and the total surge protector is further directly grounded through a grounding wire.

3. A low voltage distribution system for a sewage treatment plant according to claim 1, wherein, The control loop is provided with a reactive power compensation loop multi-channel controller, and the reactive power compensation loop multi-channel controller is used for controlling the plurality of reactive power compensation sub-loops.

4. A low voltage distribution system for a sewage treatment plant according to claim 1, wherein, The reactive power compensation loop further comprises a reactive power compensation loop busbar, and the reactive power compensation loop busbar is further provided with a reactive power compensation loop disconnector and a reactive power compensation loop circuit breaker between the busbar.

5. A low voltage distribution system for a sewage treatment plant according to claim 4, wherein, The incoming line end of the reactive power compensation loop disconnector is connected with the busbar, the outgoing line end of the reactive power compensation loop disconnector is connected with the incoming line end of the reactive power compensation loop circuit breaker, the outgoing line end of the reactive power compensation loop circuit breaker is directly connected with the reactive power compensation loop busbar, and a group of reactive power compensation loop current transformers are further arranged between the outgoing line end of the reactive power compensation loop circuit breaker and the reactive power compensation loop busbar.

6. A low voltage distribution system for a sewage treatment plant according to claim 5, wherein, The reactive power compensation loop busbar is connected in parallel with a plurality of reactive power compensation sub-loops and a group of reactive power compensation loop surge protectors, and the reactive power compensation loop surge protectors need to be directly grounded through grounding wires.

7. A low voltage distribution system for a sewage treatment plant as claimed in claim 1, wherein, The reactive power compensation sub-loop comprises a fuse, one end of the fuse is directly connected with the reactive power compensation loop busbar, the other end of the fuse is connected with a reactive power compensation contactor, the other end of the reactive power compensation contactor is connected with one end of a reactor, and the other end of the reactor is connected with a reactive power compensation capacitor group.

8. A low voltage distribution system for a sewage treatment plant according to claim 1, wherein, The load loop comprises a load loop circuit breaker, the incoming line end of the load loop circuit breaker is directly connected with the busbar, the outgoing line end of the load loop circuit breaker is directly connected with a load, and a group of load loop current transformers are further arranged between the outgoing line end of the load loop circuit breaker and the load; or, The outgoing line end of the load loop circuit breaker is connected with one end of a load loop contactor, the other end of the load loop contactor is connected with a thermal relay, and the other end of the thermal relay is connected with the load.

9. A low voltage distribution system for a sewage treatment plant as claimed in claim 1, wherein, The transformer is a 660V voltage grade transformer, the bus bar is of 660V voltage grade; the external power grid is of 10kV or 35kV voltage grade; the incoming line total switch and the incoming line current transformer are of 660V voltage grade, and the total surge protector circuit, the reactive compensation circuit and the low-voltage switch cabinet circuit are of 660V voltage grade.

Images