Device and method for controlling operation efficiency of circulating water system based on differential protection

Abstract

The invention belongs to the field of efficiency optimization of a circulating water pump system of a thermal power plant, and provides an operation efficiency control device and method of a circulating water system based on differential protection. The second end of the motor neutral point current transformer switching box is connected to the first end of the motor neutral point current transformer switching box, and the second end of the motor neutral point current transformer switching box is connected to the power distribution device; the intelligent controller is connected to the two-speed motor and the motor neutral point current transformer switching box. The intelligent controller is configured to judge whether the current running state of the motor is consistent with a target state or not according to acquired current running state data of the circulating water pump two-speed motor, if yes, the current state is kept unchanged, and if not, the neutral point current transformer switching box of the motor is controlled to be synchronously switched to the target state. And the cooling effect and the energy utilization efficiency of the thermal power plant are ensured to reach the optimal state.

Description

Technical Field

[0001] The present invention belongs to the field of optimizing the efficiency of the circulating water pump system in thermal power plants, and particularly relates to an operating efficiency control device and method for a circulating water system based on differential protection. Background Technique

[0002] The statements in this part merely provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] In the circulating water pump system of thermal power plants, the application of two-speed motors is extensive and crucial. Especially when dealing with seasonal operating conditions, such as high temperatures in summer and low temperatures in winter, their high efficiency and flexibility are particularly important. Such motors can flexibly switch between high speed and low speed according to actual needs to optimize the operating efficiency of the circulating water system and ensure that the cooling effect and energy utilization efficiency of the thermal power plant reach the best state.

[0004] The design of two-speed motors allows them to adjust their speeds under different load conditions to adapt to different operating requirements. In summer, due to the high ambient temperature and increased cooling demand, the motor needs to operate in the high-speed mode to provide greater flow and pressure to ensure the effectiveness of the cooling system. In winter, as the ambient temperature drops and the cooling demand decreases, the motor switches to the low-speed mode to reduce energy consumption and improve operating economy.

[0005] Given that the power of the circulating water pump motors in thermal power plants is relatively large, once a failure occurs, the scope of influence and consequences can be quite serious. Therefore, configuring differential protection becomes a necessary safety measure. Differential protection can quickly detect and isolate short-circuit faults occurring inside or outside the motor, effectively prevent the expansion of faults, and protect the safe and stable operation of the motor and the entire power system.

[0006] However, when the motor switches between high-speed and low-speed operations, the traditional method is to change the connection of the current transformer output terminals at the motor output end. This process is not only complex but also has many inconveniences and risks. Specifically, the wiring modification operation usually requires scaffolding, increasing the risk of working at heights; during the wiring modification operation, the entire system is in a downtime. At the same time, the wiring modification process is cumbersome and prone to errors. Once the wiring is incorrect, it may lead to protection failure or misoperation, affecting the normal operation and safety of the motor and the reliability and stability of the entire circulating water system. Summary of the Invention

[0007] To solve at least one of the technical problems existing in the above-mentioned background art, the first aspect of the present invention provides an operating efficiency control device for a circulating water system based on differential protection, which does not require cumbersome wiring modification, avoids the risks brought by the rewiring of current transformers during the high-low speed switching process of a two-speed motor, designs an intelligent switching mechanism, reduces the system downtime caused by wiring modification operations, and improves the reliability and stability of the entire circulating water system.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] An operating efficiency control device for a circulating water system based on differential protection includes a motor neutral point current transformer junction box, a motor neutral point current transformer switching box, and an intelligent controller;

[0010] The first end of the motor neutral point current transformer junction box is connected to a two-speed motor, and the second end is connected to the first end of the motor neutral point current transformer switching box. The second end of the motor neutral point current transformer switching box is connected to a power distribution device; the intelligent controller is respectively connected to a circulating water pump two-speed motor and the motor neutral point current transformer switching box;

[0011] The intelligent controller is configured to: based on the obtained operating state data of the current circulating water pump two-speed motor, determine whether the current operating state of the motor is consistent with the target state. If they are consistent, the current state remains unchanged; if they are inconsistent, the motor neutral point current transformer switching box is controlled to synchronously switch to the target state.

[0012] Further, the motor neutral point current transformer junction box includes three-phase connection terminals and a first current transformer connection terminal; the three-phase connection terminals are connected to the windings of the two-speed motor. The motor neutral point current transformer switching box includes a second current transformer connection terminal, a plurality of switching switches, and contacts; the first end of the second current transformer connection terminal is connected to the first current transformer connection terminal, and the second end is connected to the switching switches. Each contact includes a high-speed outlet contact and a low-speed outlet contact. When the switching switch switches to the corresponding contact, the corresponding circuit is connected.

[0013] Further, the first current transformer connection terminal includes a plurality of connection terminals, and each connection terminal includes a current inflow end 1S1 and a current outflow end 1S2 of the current transformer winding; the second current transformer connection terminal includes CT2-1S1, CT2-1S2, CT2 × -1S1, CT2 × -1S2, CT4-1S1, CT4-1S2, CT4 × -1S1, CT4 ×-1S2, CT6-1S1, CT6-1S2, CT6 × -1S1, CT6 × -1S2; The current input terminal 1S1 and the current output terminal 1S2 corresponding to 1U1 in the three-phase terminal are respectively connected to the second current transformer terminal CT2 × -1S1, CT2 × -1S2;

[0014] The current input terminal 1S1 and the current output terminal 1S2 corresponding to 1V1 in the three-phase terminal are respectively connected to the second current transformer terminal CT4 × -1S1, CT4 × -1S2;

[0015] The current input terminal 1S1 and the current output terminal 1S2 corresponding to 1W1 in the three-phase terminal are respectively connected to the second current transformer terminal CT6 × -1S1, CT6 × -1S2;

[0016] The current input terminal 1S1 and the current output terminal 1S2 corresponding to 1W2 in the three-phase terminal are respectively connected to the second current transformer terminals CT6-1S1, CT6-1S2;

[0017] The current input terminal 1S1 and the current output terminal 1S2 corresponding to 1U2 in the three-phase terminal are respectively connected to the second current transformer terminals CT2-1S1, CT2-1S2;

[0018] The current input terminal 1S1 and the current output terminal 1S2 corresponding to 1V2 in the three-phase terminal are respectively connected to the second current transformer terminals CT4-1S1, CT4-1S2.

[0019] Further, CT2-1S1 is connected to the first switching switch. When the high-speed outlet contact corresponding to the first switching switch is closed, the CT2-A line is connected. When the low-speed outlet contact corresponding to the first switching switch is closed, the CT2-a line is connected, CT2 × -1S1 is connected to the second switching switch. When the high-speed outlet contact corresponding to the second switching switch is closed, the CT2 × -A line is connected. When the low-speed outlet contact corresponding to the second switching switch is closed, the CT2 × -c line is connected. CT4-1S1 is connected to the third switching switch. When the high-speed outlet contact corresponding to the third switching switch is closed, the CT4-B line is connected. When the low-speed outlet contact corresponding to the third switching switch is closed, the CT4-c line is connected, CT4 × -1S1 is connected to the fourth switching switch. When the high-speed outlet contact corresponding to the fourth switching switch is closed, the CT4× - Circuit B: When the low-speed outlet contact corresponding to the fourth switching switch is closed, CT4 is connected. × - Circuit b: CT6-1S1 is connected to the fifth switching switch. When the high-speed outlet contact corresponding to the fifth switching switch is closed, CT6-C circuit is connected. When the low-speed outlet contact corresponding to the fifth switching switch is closed, CT6-b circuit is connected. CT6 × - 1S1 is connected to the sixth switching switch. When the high-speed outlet contact corresponding to the sixth switching switch is closed, CT6 is connected. × - Circuit C: When the low-speed outlet contact corresponding to the sixth switching switch is closed, CT6 is connected. × - Circuit a;

[0020] CT2-A circuit, CT2-a circuit, CT2 × - Circuit A and CT6 × - After being connected to Circuit a, they are connected to Phase A of the three-phase power supply of the distribution device. CT4-B circuit, CT4 × - Circuit B, CT4 × - Circuit b and CT6-b circuit are connected to Phase B of the three-phase power supply of the distribution device. CT2 × - Circuit c, CT4-c circuit, CT6-C circuit and CT6 × - After being connected to Circuit C, they are connected to Phase C of the three-phase power supply of the distribution device.

[0021] Furthermore, control the motor neutral current transformer switching box to synchronously switch to the target state, specifically including: when the motor is running at low speed, according to the differential protection principle of the circulating water pump two-speed motor in the high-speed state, control the motor neutral current transformer switching box to synchronously switch, and control the circulating water pump two-speed motor to switch to the high-speed running state. When the circulating water pump two-speed motor is running at high speed, according to the differential protection principle of the circulating water pump two-speed motor in the low-speed state, control the motor neutral current transformer switching box to synchronously switch, and control the circulating water pump two-speed motor to switch to the low-speed running state.

[0022] Furthermore, the differential protection principle of the motor in the high-speed state is: in the high-speed state, the three-phase terminal blocks 1U1 and 1U2 are connected in parallel as CT2-A phase, and are differentially protected with Phase A of the three-phase power supply of the distribution device; the three-phase terminal blocks 1V1 and 1V2 are connected in parallel as CT2-B phase, and are differentially protected with Phase B of the three-phase power supply of the distribution device; 1W1 and 1W2 are connected in parallel as CT2-C phase, and are differentially protected with Phase C of the switch cabinet;

[0023] The differential protection principle of the motor in the low-speed state is as follows: in the low-speed state, the three-phase connection terminals 1U2 and 1W1 are connected in parallel as the CT2-a phase, and are differentially protected with the A-phase of the switchgear; 1V1 and 1W2 are connected in parallel as the CT2-b phase, and are differentially protected with the B-phase of the three-phase power supply of the distribution device; the three-phase connection terminals 1U1 and 1V2 are connected in parallel as the CT2-c phase, and are differentially protected with the C-phase of the three-phase power supply of the distribution device.

[0024] Furthermore, the intelligent controller is further configured to: during the switching process, obtain the motor switching state data in real time, determine whether the switching is successful according to the motor switching state data, if the switching fails, determine the corresponding switching failure type according to the motor switching state data, and generate a retry mechanism according to the corresponding switching failure type, and re-switch according to the generated retry mechanism.

[0025] To solve the above problems, the second aspect of the present invention provides an operation efficiency control method for a circulating water system based on differential protection, which does not require cumbersome wiring modification, avoids the risks brought by the rewiring of current transformers during the high-low speed switching process of a two-speed motor, designs an intelligent switching mechanism, reduces the system downtime caused by wiring modification operations, and improves the reliability and stability of the entire circulating water system.

[0026] To achieve the above object, the present invention adopts the following technical solutions:

[0027] The operation efficiency control method for a circulating water system based on differential protection, and the operation efficiency control device for a circulating water system based on differential protection described in the second aspect, includes the following steps:

[0028] Obtain the operation state data of the current circulating water pump two-speed motor, and determine the current operation state of the two-speed motor as high speed or low speed according to the operation state data;

[0029] Judge whether the operation state of the current circulating water pump two-speed motor is consistent with the target state. If they are consistent, keep the current state unchanged. If they are inconsistent, control the motor neutral point current transformer switching box to synchronously switch to the target state.

[0030] Furthermore, controlling the motor neutral point current transformer switching box to synchronously switch to the target state specifically includes: when the motor is running at low speed, according to the differential protection principle of the circulating water pump two-speed motor in the high-speed state, control the motor neutral point current transformer switching box to synchronously switch, and control the circulating water pump two-speed motor to switch to the high-speed operation state. When the circulating water pump two-speed motor is running at high speed, according to the differential protection principle of the circulating water pump two-speed motor in the low-speed state, control the motor neutral point current transformer switching box to synchronously switch, and control the circulating water pump two-speed motor to switch to the low-speed operation state.

[0031] Furthermore, during the switching process, the switching status data of the motor is obtained in real time, and it is determined whether the switching is successful according to the switching status data of the motor. If the switching fails, the corresponding switching failure type is determined according to the switching status data of the motor, and a retry mechanism is generated according to the corresponding switching failure type, and the switching is performed again according to the generated retry mechanism.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. The present invention provides an operating efficiency control device for a circulating water system based on differential protection, which does not require cumbersome wiring changes, avoids the risks brought by the rewiring of current transformers during the high and low speed switching of a two-speed motor, designs an intelligent switching mechanism, reduces the system downtime caused by wiring change operations, and improves the reliability and stability of the entire circulating water system.

[0034] 2. The device of the present invention can integrate an intelligent control unit, which can monitor the switching status of the current transformer in real time, automatically adjust the protection parameters, and ensure the accuracy and reliability of differential protection.

[0035] Advantages of additional aspects of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The schematic diagrams in the specification forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0037] Figure 1 is a schematic connection diagram of an operating efficiency control device for a circulating water system based on differential protection provided by an embodiment of the present invention;

[0038] Figure 2 is a schematic wiring diagram of a two-speed motor of a circulating water pump provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The present invention will be further described below in conjunction with the drawings and embodiments.

[0040] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0041] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0042] In the present invention, terms such as "connected" and "coupled" should be understood in a broad sense, which may mean a fixed connection, an integral connection or a detachable connection; it may be directly connected or indirectly connected through an intermediate medium. For those related scientific research or technical personnel in the field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances, and should not be construed as a limitation to the present invention.

[0043] Embodiment 1

[0044] This embodiment provides an operating efficiency control device for a circulating water system based on differential protection, including a motor neutral point current transformer junction box, a motor neutral point current transformer switching box, and an intelligent controller;

[0045] The first end of the motor neutral point current transformer junction box is connected to a two-speed motor, and the second end is connected to the first end of the motor neutral point current transformer switching box. The second end of the motor neutral point current transformer switching box is connected to a power distribution device; the intelligent controller is respectively connected to the two-speed motor and the motor neutral point current transformer switching box;

[0046] As Figure 1 shown, the motor neutral point current transformer junction box, corresponding to the D1 frame in the figure, provides necessary wiring interfaces for the motor.

[0047] The motor neutral point current transformer switching box, corresponding to the D2 frame in the figure, is the core part of the device and is responsible for leading the CT terminals to the inside of the switching device. The CT intelligent switching device, corresponding to the D3 frame in the figure, includes a connecting piece (2-1-1) for realizing the switching of different connection methods of the secondary CT of the motor in the high-speed and low-speed states. The changeover switch: automatically selects the corresponding CT connection method according to the operating state (high speed or low speed) of the motor.

[0048] The motor neutral point current transformer junction box includes three-phase wiring terminals and a first current transformer wiring terminal; the three-phase wiring terminals are connected to the windings of the two-speed motor, and the first current transformer wiring terminal is connected to the motor neutral point current transformer switching box;

[0049] The three-phase terminal includes 1U1, 1V1, 1W1, 1W2, 1U2, 1V2, 2U1, 2V1, 2W1. The first current transformer terminal includes a plurality of terminals, and each terminal includes a current input end 1S1 and a current output end 1S2 of the current transformer winding;

[0050] The motor neutral point current transformer switching box includes a second current transformer terminal, a plurality of switching switches and contacts;

[0051] The first end of the second current transformer terminal is connected to the first current transformer terminal, the second end is connected to the switching switch, and each contact includes a high-speed outlet contact and a low-speed outlet contact. When the switching switch switches to the corresponding contact, the corresponding circuit is connected; the contact is connected to the three-phase power supply of the distribution device.

[0052] For Figure 1 example, the second current transformer terminal includes CT2-1S1, CT2-1S2, CT2 × -1S1, CT2 × -1S2, CT4-1S1, CT4-1S2, CT4 × -1S1, CT4 × -1S2, CT6-1S1, CT6-1S2, CT6 × -1S1, CT6 × -1S2;

[0053] The current input end 1S1 and the current output end 1S2 corresponding to 1U1 in the three-phase terminal are respectively connected to the second current transformer terminal CT2 × -1S1, CT2 × -1S2;

[0054] The current input end 1S1 and the current output end 1S2 corresponding to 1V1 in the three-phase terminal are respectively connected to the second current transformer terminal CT4 × -1S1, CT4 × -1S2;

[0055] The current input end 1S1 and the current output end 1S2 corresponding to 1W1 in the three-phase terminal are respectively connected to the second current transformer terminal CT6 × -1S1, CT6 × -1S2;

[0056] The current input end 1S1 and the current output end 1S2 corresponding to 1W2 in the three-phase terminal are respectively connected to the second current transformer terminal CT6-1S1, CT6-1S2;

[0057] The current input terminal 1S1 and the current output terminal 1S2 corresponding to 1U2 in the three-phase terminal are respectively connected to the current transformer terminal CT2-1S1 and CT2-1S2 of the second current transformer;

[0058] The current input terminal 1S1 and the current output terminal 1S2 corresponding to 1V2 in the three-phase terminal are respectively connected to the current transformer terminal CT4-1S1 and CT4-1S2 of the second current transformer;

[0059] Among them, CT2-1S1 is connected to the first switching switch. When the high-speed outlet contact corresponding to the first switching switch is closed, the CT2-A line is connected. When the low-speed outlet contact corresponding to the first switching switch is closed, the CT2-a line is connected. CT2 × -1S1 is connected to the second switching switch. When the high-speed outlet contact corresponding to the second switching switch is closed, the CT2 × -A line is connected. When the low-speed outlet contact corresponding to the second switching switch is closed, the CT2 × -c line is connected. CT4-1S1 is connected to the third switching switch. When the high-speed outlet contact corresponding to the third switching switch is closed, the CT4-B line is connected. When the low-speed outlet contact corresponding to the third switching switch is closed, the CT4-c line is connected. CT4 × -1S1 is connected to the fourth switching switch. When the high-speed outlet contact corresponding to the fourth switching switch is closed, the CT4 × -B line is connected. When the low-speed outlet contact corresponding to the fourth switching switch is closed, the CT4 × -b line is connected. CT6-1S1 is connected to the fifth switching switch. When the high-speed outlet contact corresponding to the fifth switching switch is closed, the CT6-C line is connected. When the low-speed outlet contact corresponding to the fifth switching switch is closed, the CT6-b line is connected. CT6 × -1S1 is connected to the sixth switching switch. When the high-speed outlet contact corresponding to the sixth switching switch is closed, the CT6 × -C line is connected. When the low-speed outlet contact corresponding to the sixth switching switch is closed, the CT6 × -a line;

[0060] CT2-A line, CT2-a line, CT2 × -A line and CT6 × -a line are connected and then connected to the A phase of the three-phase power supply of the distribution device. CT4-B line, CT4 × -B line, CT4 × -b line and CT6-b line are connected to the B phase of the three-phase power supply of the distribution device. CT2 × -c line, CT4-c line, CT6-C line and CT6 × -C line are connected and then connected to the C phase of the three-phase power supply of the distribution device;

[0061] Connect the second changeover switch, the third changeover switch, the fourth changeover switch, the fifth changeover switch, the sixth changeover switch to the corresponding second current transformer terminal block and then connect them to the N phase of the three-phase power supply of the distribution device.

[0062] In this embodiment, the distribution device adopts a 10 kV distribution device.

[0063] The intelligent controller is configured to: according to the obtained operation state data of the current circulating water pump two-speed motor, judge whether the current operation state of the motor is consistent with the target state. If they are consistent, keep the current state unchanged. If they are inconsistent, control the motor neutral point current transformer switching box to synchronously switch to the target state.

[0064] The specific switching process is as follows:

[0065] If the instruction is to switch to the high-speed operation state, obtain the operation state data of the current circulating water pump two-speed motor. If the circulating water pump two-speed motor is in the high-speed operation state, keep it unchanged. If the circulating water pump two-speed motor is in the low-speed operation state, according to the differential protection principle of the motor in the high-speed state, control the motor neutral point current transformer switching box to synchronously switch, control the circulating water pump two-speed motor to switch to the high-speed operation state, and ensure the correctness of the differential protection; at the same time, the intelligent controller confirms whether the switching is successful through the feedback signal line and feeds back the result to the external system or the operator.

[0066] If the instruction is to switch to the low-speed operation state, obtain the operation state data of the current circulating water pump two-speed motor. If the circulating water pump two-speed motor is in the low-speed operation state, keep it unchanged. If the circulating water pump two-speed motor is in the high-speed operation state, according to the differential protection principle of the circulating water pump two-speed motor in the low-speed state, control the motor neutral point current transformer switching box to synchronously switch, control the circulating water pump two-speed motor to switch to the low-speed operation state, and ensure the correctness of the differential protection; at the same time, the intelligent controller confirms whether the switching is successful through the feedback signal line and feeds back the result to the external system or the operator.

[0067] As Figure 2 shown, the differential protection principle of the motor in the high-speed state is: the differential protection principle of the motor in the high-speed state is: in the high-speed state, the three-phase terminal blocks 1U1 and 1U2 are connected in parallel as the CT2-A phase and are differential with the A phase of the three-phase power supply of the distribution device; the three-phase terminal blocks 1V1 and 1V2 are connected in parallel as the CT2-B phase and are differential with the B phase of the three-phase power supply of the distribution device; 1W1 and 1W2 are connected in parallel as the CT2-C phase and are differential with the C phase of the switch cabinet;

[0068] The differential protection principle of the motor in the low-speed state is as follows: in the low-speed state, the three-phase terminal 1U2 and 1W1 are connected in parallel as the CT2-a phase, and are differentially protected with the A phase of the switchgear; 1V1 and 1W2 are connected in parallel as the CT2-b phase, and are differentially protected with the B phase of the three-phase power supply of the distribution device; the three-phase terminal 1U1 and 1V2 are connected in parallel as the CT2-c phase, and are differentially protected with the C phase of the three-phase power supply of the distribution device.

[0069] In addition, the device further includes: during the switching process, the switching state data of the motor is obtained in real time, including the connection state of the current transformer, the operating parameters of the motor, and the switching switch state data; it is judged whether the switching is successful according to the switching state data of the motor. If the switching fails, the corresponding switching failure type is judged according to the switching state data of the motor, and a retry mechanism is generated according to the corresponding switching failure type, and the switching is retried according to the generated retry mechanism.

[0070] For example, assume that during the process of switching from low speed to high speed, the switching switch (such as the first switching switch) fails and fails to correctly connect to the high-speed outlet contact (such as the CT2-A line), resulting in the motor being unable to switch to the high-speed operating state. The intelligent controller obtains the switching state data of the motor in real time through the connection with the neutral point current transformer switching box of the motor, and finds that the switching fails. Subsequently, the intelligent controller will try to perform the switching operation again, and the number of retries and the time interval can be set according to actual requirements. After each retry fails, the system will record the fault information, including the fault time and the number of retries, for subsequent analysis and maintenance.

[0071] In addition, the device further includes: the intelligent control unit is responsible for real-time monitoring of the operating state of the motor, and controlling the action of the switching switch according to the state. During the high and low speed switching process, the protection parameters are automatically adjusted to ensure that the protection device is always in the best working state; the human-machine interface provides an intuitive visual operation interface and indicator lights, enabling the operator to easily understand the current switching state and reducing the risk of misoperation.

[0072] Embodiment 2

[0073] This embodiment provides a method for controlling the operating efficiency of a circulating water system based on differential protection. Based on the device for controlling the operating efficiency of a circulating water system based on differential protection described in Embodiment 1, the method includes the following steps:

[0074] Step 1: Obtain the operating state data of the current circulating water pump two-speed motor;

[0075] Step 2: Judge whether the current operating state of the two-speed motor is high speed or low speed according to the obtained operating state data of the current motor;

[0076] Step 3: Determine whether the current operating state of the motor is consistent with the target state. If they are consistent, keep the current state unchanged; if not, control the synchronous switching of the motor neutral point current transformer switching box to the target state.

[0077] Among them, in Step 3, the specific switching process of controlling the synchronous switching of the motor neutral point current transformer switching box to the target state is as follows:

[0078] If the instruction is to switch to the high-speed operation state, obtain the operating state data of the current circulating water pump two-speed motor. If the circulating water pump two-speed motor is in the high-speed operation state, keep it unchanged. If the circulating water pump two-speed motor is in the low-speed operation state, according to the differential protection principle of the motor in the high-speed state, control the synchronous switching of the motor neutral point current transformer switching box, control the circulating water pump two-speed motor to switch to the high-speed operation state, and ensure the correctness of differential protection; at the same time, the intelligent controller confirms whether the switching is successful through the feedback signal line and feeds back the result to the external system or the operator.

[0079] If the instruction is to switch to the low-speed operation state, obtain the operating state data of the current circulating water pump two-speed motor. If the circulating water pump two-speed motor is in the low-speed operation state, keep it unchanged. If the circulating water pump two-speed motor is in the high-speed operation state, according to the differential protection principle of the circulating water pump two-speed motor in the low-speed state, control the synchronous switching of the motor neutral point current transformer switching box, control the circulating water pump two-speed motor to switch to the low-speed operation state, and ensure the correctness of differential protection; at the same time, the intelligent controller confirms whether the switching is successful through the feedback signal line and feeds back the result to the external system or the operator.

[0080] The differential protection principle of the motor in the high-speed state is: The differential protection principle of the motor in the high-speed state is: In the high-speed state, the three-phase connection terminals 1U1 and 1U2 are connected in parallel as the CT2-A phase, and are differentially protected with the three-phase power supply A phase of the distribution device; the three-phase connection terminals 1V1 and 1V2 are connected in parallel as the CT2-B phase, and are differentially protected with the three-phase power supply B phase of the distribution device; 1W1 and 1W2 are connected in parallel as the CT2-C phase, and are differentially protected with the switch cabinet C phase;

[0081] The differential protection principle of the motor in the low-speed state is: In the low-speed state, the three-phase connection terminals 1U2 and 1W1 are connected in parallel as the CT2-a phase, and are differentially protected with the switch cabinet A phase; 1V1 and 1W2 are connected in parallel as the CT2-b phase, and are differentially protected with the three-phase power supply B phase of the distribution device; the three-phase connection terminals 1U1 and 1V2 are connected in parallel as the CT2-c phase, and are differentially protected with the three-phase power supply C phase of the distribution device.

[0082] During the switching process, the switching state data of the motor is obtained in real time, and it is judged whether the switching is successful according to the switching state data of the motor. If the switching fails, the corresponding switching failure type is judged according to the switching state data of the motor. According to the corresponding switching failure type, a retry mechanism is generated, and the switching is restarted according to the generated retry mechanism.

[0083] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An operating efficiency control device for a circulating water system based on differential protection, characterized in that: It includes a motor neutral point current transformer junction box, a motor neutral point current transformer switch box and an intelligent controller; The first end of the motor neutral point current transformer junction box is connected to the dual-speed motor, and the second end is connected to the first end of the motor neutral point current transformer switch box, and the second end of the motor neutral point current transformer switch box is connected to the power distribution device; the intelligent controller is respectively connected to the circulating water pump dual-speed motor and the motor neutral point current transformer switch box; The intelligent controller is configured to: determine whether the current operating state of the motor is consistent with the target state based on the operating state data of the current circulating water pump dual-speed motor. If they are consistent, the current state is kept unchanged; if they are inconsistent, the motor neutral point current transformer switching box is controlled to synchronously switch to the target state.

2. The operating efficiency control device of a circulating water system based on differential protection according to claim 1, characterized in that: The motor neutral point current transformer junction box includes a three-phase terminal and a first current transformer terminal; the three-phase terminal is connected to the winding of the dual-speed motor, and the motor neutral point current transformer switching box includes a second current transformer terminal, a plurality of switching switches and contacts; the first end of the second current transformer terminal is connected to the first current transformer terminal, and the second end is connected to the switching switch, each contact includes a high-speed output contact and a low-speed output contact, and when the switching switch is switched to the corresponding contact, the corresponding line is connected.

3. The operating efficiency control device of a circulating water system based on differential protection according to claim 2, characterized in that: The first current transformer terminal includes a plurality of terminals, each of which includes a current inflow terminal 1S1 and a current outflow terminal 1S2 of a current transformer winding; the second current transformer terminal includes CT2-1S1, CT2-1S2, CT2 × -1S1, CT2 × -1S2, CT4-1S1, CT4-1S2, CT4 × -1S1、CT4 × -1S2, CT6-1S1, CT6-1S2, CT6 × -1S1, CT6 × -1S2; the current inflow terminal 1S1 and the current outflow terminal 1S2 corresponding to 1U1 in the three-phase terminal are respectively connected to the second current transformer terminal CT2 × -1S1, CT2 × -1S2; The current inflow terminal 1S1 and the current outflow terminal 1S2 corresponding to 1V1 in the three-phase terminal are respectively connected to the second current transformer terminal CT4 × -1S1、CT4 × -1S2; The current inflow terminal 1S1 and the current outflow terminal 1S2 corresponding to the three-phase terminal 1W1 are respectively connected to the second current transformer terminal CT6 × -1S1, CT6 × -1S2; The current inflow terminal 1S1 and the current outflow terminal 1S2 corresponding to the three-phase terminal 1W2 are connected to the second current transformer terminals CT6-1S1 and CT6-1S2 respectively; The current inflow terminal 1S1 and the current outflow terminal 1S2 corresponding to the three-phase terminal 1U2 are connected to the second current transformer terminals CT2-1S1 and CT2-1S2 respectively; The current inflow terminal 1S1 and the current outflow terminal 1S2 corresponding to 1V2 in the three-phase terminal are connected to the second current transformer terminal CT4-1S1 and CT4-1S2 respectively.

4. The operating efficiency control device of a circulating water system based on differential protection according to claim 3, characterized in that: CT2-1S1 is connected to the first switch. When the high-speed output contact corresponding to the first switch is turned on, the CT2-A line is turned on. When the low-speed output contact corresponding to the first switch is turned on, the CT2-a line is turned on. × -1S1 is connected to the second switch. When the high-speed output contact corresponding to the second switch is turned on, CT2 is turned on. × -A line, when the low-speed exit contact corresponding to the second switch is turned on, CT2 is turned on × -c line, CT4-1S1 is connected to the third switch. When the high-speed output contact corresponding to the third switch is turned on, the CT4-B line is turned on. When the low-speed output contact corresponding to the third switch is turned on, the CT4-c line is turned on. × -1S1 is connected to the fourth switch. When the high-speed output contact corresponding to the fourth switch is turned on, CT4 is turned on. × -B line, when the low-speed exit contact corresponding to the fourth switch is turned on, CT4 is turned on × -b line, CT6-1S1 is connected to the fifth switch. When the high-speed output contact corresponding to the fifth switch is turned on, the CT6-C line is turned on. When the low-speed output contact corresponding to the fifth switch is turned on, the CT6-b line is turned on. × -1S1 is connected to the sixth switch. When the high-speed output contact corresponding to the sixth switch is turned on, CT6 is turned on. × -C line, when the low-speed exit contact corresponding to the sixth switch is connected, CT6 is connected × -a line; CT2-A line, CT2-a line, CT2 × -A Line and CT6 × -a line is connected to the A phase of the three-phase power supply of the power distribution device, CT4-B line, CT4 × -B line, CT4 × -b line and CT6-b line are connected to phase B of the three-phase power supply of the distribution device, CT2 × -c line, CT4-c line, CT6-C line and CT6 × -C lines are connected to the C phase of the three-phase power supply of the power distribution device.

5. The operation efficiency control device of a circulating water system based on differential protection according to claim 1, characterized in that: Control the motor neutral point current transformer switching box to switch synchronously to the target state, specifically including: if the motor is running at a low speed, according to the differential protection principle of the circulating water pump two-speed motor in the high-speed state, control the motor neutral point current transformer switching box to switch synchronously, and control the circulating water pump two-speed motor to switch to a high-speed running state; if the circulating water pump two-speed motor is running at a high speed, according to the differential protection principle of the circulating water pump two-speed motor in the low-speed state, control the motor neutral point current transformer switching box to switch synchronously, and control the circulating water pump two-speed motor to switch to a low-speed running state.

6. The operating efficiency control device of a circulating water system based on differential protection according to claim 5, characterized in that: The differential protection principle of the motor in high-speed state is as follows: in high-speed state, the three-phase terminal 1U1 and 1U2 are connected in parallel as CT2-A phase, which is differential with the three-phase power supply A phase of the distribution device; the three-phase terminal 1V1 and 1V2 are connected in parallel as CT2-B phase, which is differential with the three-phase power supply B phase of the distribution device; 1W1 and 1W2 are connected in parallel as CT2-C phase, which is differential with the switch cabinet C phase; The differential protection principle of the motor in the low-speed state is: in the low-speed state, the three-phase terminal 1U2 and 1W1 are connected in parallel as CT2-a phase, differentially with the A phase of the switch cabinet; 1V1 and 1W2 are connected in parallel as CT2-b phase, differentially with the three-phase power supply B phase of the distribution device; the three-phase terminal 1U1 and 1V2 are connected in parallel as CT2-c phase, differentially with the three-phase power supply C phase of the distribution device.

7. The operating efficiency control device of a circulating water system based on differential protection according to claim 1, characterized in that: The intelligent controller is also configured to: during the switching process, obtain the motor switching status data in real time, determine whether the switching is successful based on the motor switching status data, if the switching fails, determine the corresponding switching failure type based on the motor switching status data, generate a retry mechanism based on the corresponding switching failure type, and switch again based on the generated retry mechanism.

8. The operation efficiency control method of the circulating water system based on differential protection is characterized in that: The operating efficiency control device of a circulating water system based on differential protection according to any one of claims 1 to 7 comprises the following steps: Acquire the current running state data of the dual-speed motor of the circulating water pump, and determine whether the current running state of the dual-speed motor is high speed or low speed according to the running state data; Determine whether the current operating state of the circulating water pump dual-speed motor is consistent with the target state. If they are consistent, keep the current state unchanged. If they are inconsistent, control the motor neutral point current transformer switching box to switch to the target state synchronously.

9. The operating efficiency control method of a circulating water system based on differential protection according to claim 8, characterized in that: Control the motor neutral point current transformer switching box to switch synchronously to the target state, specifically including: if the motor is running at a low speed, according to the differential protection principle of the circulating water pump two-speed motor in the high-speed state, control the motor neutral point current transformer switching box to switch synchronously, and control the circulating water pump two-speed motor to switch to a high-speed running state; if the circulating water pump two-speed motor is running at a high speed, according to the differential protection principle of the circulating water pump two-speed motor in the low-speed state, control the motor neutral point current transformer switching box to switch synchronously, and control the circulating water pump two-speed motor to switch to a low-speed running state.

10. The operating efficiency control method of a circulating water system based on differential protection according to claim 8, characterized in that: During the switching process, the motor switching status data is obtained in real time, and whether the switching is successful is determined based on the motor switching status data. If the switching fails, the corresponding switching failure type is determined based on the motor switching status data, and a retry mechanism is generated based on the corresponding switching failure type, and the switch is repeated based on the generated retry mechanism.

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