Load side voltage monitoring module and change-over switch

Abstract

The invention discloses a load side voltage monitoring module which is used for monitoring load side voltage of a change-over switch. The load side voltage monitoring module independently exists as a selectable accessory form of the change-over switch, and comprises a load side voltage detection unit used for collecting a load side voltage signal of the change-over switch; the microprocessor unit is used for calculating load side voltage according to the change-over switch load side voltage signal provided by the load side voltage detection unit; and the communication unit is used for realizing data interaction between the load side voltage monitoring module and the controller of the change-over switch. The invention further discloses a change-over switch. Compared with the prior art, the load-side voltage monitoring module adopts a selectable accessory form, provides a selectable load-side voltage monitoring function for a user having a load voltage monitoring requirement, enriches the function configuration of the change-over switch, reduces the size of the change-over switch controller, and improves the reliability of the change-over switch controller. And the modular and miniaturized design of the change-over switch controller can be realized conveniently.

Description

Technical Field

[0001] The present invention relates to a transfer switch, and more particularly to a load-side voltage monitoring module for monitoring the voltage on the load side of a transfer switch. Background Art

[0002] A transfer switch is an electrical device used for switching between different power sources and is widely used in situations where it is necessary to ensure the continuity and reliability of power supply. The controller included in the device usually has functions such as monitoring signals such as the incoming power supply voltage and switch position, as well as switching control functions between different power sources.

[0003] In the daily use of a transfer switch, common factors such as contact wear, vibration loosening, and corrosion and rust may cause voltage deviations between the incoming line side and the load side of the transfer switch. The voltage deviation between the incoming and outgoing lines indicates a decrease in the conductivity of the transfer switch, which not only affects the normal on-off function of the switch but also causes unstable voltage of the load device and affects the normal operation of the load device. Especially when an open circuit occurs in the main circuit inside the transfer switch, if not discovered in time, long-term operation in a single-phase loss state will cause relatively serious damage to load devices such as motors.

[0004] At present, basically all transfer switches on the market do not have the function of monitoring the load voltage and self-diagnosing the voltage of the incoming and outgoing lines, and cannot give an alarm prompt for the voltage deviation of the incoming and outgoing line sides in the above abnormal states to prevent problems before they occur; in addition, although a very small number of transfer switches have the function of monitoring the load-side voltage, in order to ensure the real-time calculation of the voltage deviation between the incoming and outgoing lines, the load-side voltage monitoring function is usually integrated into the controller body, and the microprocessor of the body synchronously calculates and compares the incoming and outgoing line voltages. In this way, devices such as voltage transformers necessary for load-side voltage monitoring will inevitably increase the volume and cost of the body controller, which is not conducive to product miniaturization and market competition. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a load-side voltage monitoring module that can realize the self-diagnosis function of the incoming and outgoing line voltages of a transfer switch, and has a simple structure and is convenient for users to flexibly configure.

[0006] The present invention specifically adopts the following technical solutions to solve the above technical problems:

[0007] A load-side voltage monitoring module for monitoring the load-side voltage of a transfer switch; comprising:

[0008] A load-side voltage detection unit for collecting the load-side voltage signal of the transfer switch;

[0009] A microprocessor unit for calculating the load-side voltage according to the load-side voltage signal of the transfer switch provided by the load-side voltage detection unit;

[0010] A communication unit for realizing data interaction between the load-side voltage monitoring module and the controller of the transfer switch.

[0011] The load-side voltage monitoring module can exist independently in the form of an optional accessory of the transfer switch.

[0012] Based on the above technical solutions, the following can also be obtained:

[0013] A transfer switch includes a controller that can collect the voltage signal on the incoming line side of the transfer switch and calculate the incoming line side voltage therefrom; the controller is connected to the load-side voltage monitoring module described in the above technical solution for data interaction; the controller performs self-diagnosis of the incoming and outgoing line voltages according to the following method: comparing the incoming line side voltage with the load-side voltage provided by the load-side voltage monitoring module, if the deviation between the two is less than or equal to a preset threshold, it is determined that the incoming and outgoing line voltages are normal, otherwise, it is determined that there is an over-tolerance fault in the incoming and outgoing line voltages.

[0014] Furthermore, the data interaction between the load-side voltage monitoring module and the controller of the transfer switch is based on the controller as the master station and the load monitoring module as the slave station. The master station periodically sends polling messages to the slave station at a polling period. After receiving the polling message, the slave station immediately returns a return message containing the load-side voltage; during the self-diagnosis process of the incoming and outgoing line voltages, the incoming line side voltage used is the average value of the incoming line side voltage within the Tx time period before the moment when the master station polling message of the current polling period is sent, and the load-side voltage used is the average value of the load-side voltage within the Tx time period before the moment when the slave station polling message of the current polling period is received. Tx is a preset time period.

[0015] Furthermore, both the incoming line side voltage and the load-side voltage are effective values of the voltage.

[0016] Furthermore, the data interaction between the load-side voltage monitoring module and the controller of the transfer switch is realized through bus communication.

[0017] Preferably, the bus communication is Modbus communication.

[0018] Preferably, the controller includes a function module expansion unit with multiple communication interfaces for realizing data interaction between the controller and multiple expansion function modules including the load-side voltage monitoring module in sequence.

[0019] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0020] The load - side voltage monitoring module of the present invention is in the form of an optional accessory, providing an optional load - side voltage monitoring function for users who need load voltage monitoring, enriching the function configuration of the transfer switch, reducing the volume of the transfer - switch controller, and facilitating the modular and miniaturized design of the transfer - switch controller.

[0021] The present invention further proposes a scheme for synchronously comparing the incoming - and outgoing - line voltages for self - diagnosis of the incoming - and outgoing - line voltages. By comparing the average voltage within a fixed time period before the moment when the master - station communication message is sent and the moment when the slave - station communication message is received, the incoming - line voltage and the load - side voltage calculated respectively on the transfer - controller body and the load - voltage monitoring module have high synchrony and stability. On the premise of meeting the voltage - detection accuracy, an over - tolerance alarm - prompt function for the incoming - line and load - side voltages is realized, providing an accurate and effective detection means for abnormal conditions such as an open circuit in the main circuit inside the transfer switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural block diagram of a specific embodiment of the transfer switch of the present invention;

[0023] Figure 2 It is a schematic diagram of the principle of the incoming - and outgoing - line voltage synchronous - comparison scheme. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Aiming at the deficiencies of the prior art, the solution idea of the present invention is to design the load - side voltage monitoring module in the form of an optional accessory, providing an optional load - side voltage monitoring function for users who need load voltage monitoring, so as to realize the modular and miniaturized design of the transfer - switch controller.

[0025] The present invention specifically adopts the following technical solutions to solve the above - mentioned technical problems:

[0026] A load - side voltage monitoring module for monitoring the load - side voltage of a transfer switch, comprising:

[0027] A load - side voltage detection unit for collecting the load - side voltage signal of the transfer switch;

[0028] A micro - processor unit for calculating the load - side voltage according to the load - side voltage signal of the transfer switch provided by the load - side voltage detection unit;

[0029] A communication unit for realizing data interaction between the load - side voltage monitoring module and the controller of the transfer switch.

[0030] The load - side voltage monitoring module can exist independently in the form of an optional accessory of the transfer switch.

[0031] Based on the above - mentioned technical solutions, it can also be obtained that:

[0032] A transfer switch includes a controller that can collect the voltage signal on the incoming line side of the transfer switch and calculate the incoming line side voltage based on this; the controller is connected to the load side voltage monitoring module described in the above technical solution for data interaction; the controller performs self-diagnosis of the incoming and outgoing line voltages according to the following method: compare the incoming line side voltage with the load side voltage provided by the load side voltage monitoring module. If the deviation between the two is less than or equal to the preset threshold, it is determined that the incoming and outgoing line voltages are normal; otherwise, it is determined that there is an over-tolerance fault in the incoming and outgoing line voltages.

[0033] Further, the data interaction between the load side voltage monitoring module and the controller of the transfer switch is based on the controller as the master station and the load monitoring module as the slave station. The master station periodically sends polling messages to the slave station at a polling period. After receiving the polling message, the slave station immediately replies with a return message containing the load side voltage; during the self-diagnosis process of the incoming and outgoing line voltages, the incoming line side voltage used is the average value of the incoming line side voltage within the Tx time period before the moment when the master station polling message of the current polling period is sent, and the load side voltage used is the average value of the load side voltage within the Tx time period before the moment when the slave station polling message of the current polling period is received. Tx is a preset time period.

[0034] Furthermore, both the incoming line side voltage and the load side voltage are root mean square voltages.

[0035] Furthermore, the data interaction between the load side voltage monitoring module and the controller of the transfer switch is realized through bus communication.

[0036] Preferably, the bus communication is Modbus communication.

[0037] Preferably, the controller includes a functional module expansion unit with multiple communication interfaces, which is used to realize the sequential data interaction between the controller and multiple expansion functional modules including the load side voltage monitoring module.

[0038] For the convenience of public understanding, the technical solution of the present invention will be described in detail below through a specific embodiment in combination with the accompanying drawings:

[0039] The transfer switch of this embodiment is as Figure 1As shown, it includes a controller and an actuator. The controller controls the actuator to achieve power switching. The controller includes a detection unit, a control unit, a module expansion unit, and a first microprocessor unit. The detection unit includes an incoming line side voltage detection unit and a switch position detection unit, etc. The incoming line side voltage detection unit is responsible for collecting the incoming line side voltage signal of the transfer switch and providing the incoming line side voltage information to the first microprocessor unit. The switch position detection unit is responsible for collecting the transfer switch position signal and providing the switch position information to the first microprocessor unit. The control unit drives the actuator to act according to the instructions provided by the first microprocessor unit. The module expansion unit has multiple communication interfaces to achieve the function expansion of the controller. In this embodiment, the function module is expanded through the Modbus bus form. When the function module is plugged into the controller through the physical expansion interface, after the controller recognizes the expansion function module, the controller can achieve the corresponding function expansion through the expansion function module. When the function module is removed from the physical expansion interface, after the controller recognizes the removal of the expansion module, the controller no longer supports the expansion function of the corresponding function module. The first microprocessor unit is the functional core of the transfer switch controller, electrically connected to the above units to achieve data interaction with other units.

[0040] As Figure 1 shown, the transfer switch of this embodiment further includes a load side voltage monitoring module that exists independently in the form of an optional accessory. When the customer needs it, it can be connected to the transfer switch controller through the module expansion unit as an expansion function module to achieve the expansion of the load side voltage monitoring and the incoming and outgoing line voltage self-diagnosis functions. The load side voltage monitoring module includes a load side voltage detection unit, a second microprocessor unit, and a communication unit. The load side voltage detection unit is used to collect the load side voltage signal of the transfer switch. The second microprocessor unit is used to calculate the load side voltage according to the load side voltage signal of the transfer switch provided by the load side voltage detection unit. The communication unit is used to achieve data interaction between the load side voltage monitoring module and the controller of the transfer switch.

[0041] In this embodiment, the voltage algorithms used for the incoming line side voltage and the load side voltage are both effective value algorithms, and the calculation formula is:

[0042]

[0043] In the formula, Ui represents the effective value of the i-phase bus voltage in the current sampling period, N is the number of samples in a cycle, Ui[n] represents the nth voltage sample value in a cycle, and Xs is the voltage correction coefficient. The preferred calculation period under the commercial power is 20ms.

[0044] While the controller monitors the incoming line voltage, the load side voltage monitoring module monitors the load side voltage in real time and transmits the monitored load side voltage to the controller to realize the display of the load side voltage on the controller. At the same time, the controller can also compare the incoming line voltage and the load side voltage, and issue a fault alarm prompt when the voltage difference exceeds the set threshold, and cancel the fault alarm prompt when the voltage difference is less than or equal to the set threshold.

[0045] The incoming line voltage in the above technical solution is detected by the controller, and the load side voltage is detected by the load voltage monitoring module. The controller and the load voltage monitoring module perform data interaction through the Modbus bus method, and it takes time to perform data transmission and parsing through the Modbus bus or other methods. To solve the synchronization problem of the voltages calculated on the microprocessors of two different devices after transmission, in this embodiment, a further incoming and outgoing line voltage synchronization comparison scheme is proposed for incoming and outgoing line voltage self-diagnosis, and its principle is as Figure 2 shown as follows:

[0046] In the Modbus communication of this embodiment, the transfer switch controller is the master station and the load monitoring module is the slave station; the master station periodically sends polling messages to the slave station at a polling period, and this polling period can be a fixed period or an unfixed period. After receiving the polling message, the slave station parses and processes the message and then replies to the master station. The returned message contains the load side voltage of the slave station. The specific operation process is as follows:

[0047] (1) Taking one phase as an example, create a voltage effective value cache array Ui

[50] in the master station, and this array can store 50 effective values of the incoming line voltage of this phase within 1 second; correspondingly, create a voltage effective value cache array Uo

[50] in the slave station, and this array can store 50 effective values of the load side voltage of this phase within 1 second;

[0048] (2) The master station performs real-time operation on the effective value of the incoming line voltage. The calculation period of the incoming line voltage is 20ms, and the calculated effective values are sequentially stored in the cache array Ui

[50] . After each storage, the array subscript is incremented by 1. When the array subscript reaches 49, the array subscript is reset to 0; correspondingly, the slave station performs real-time operation on the effective value of the load side voltage. The calculation period of the load side voltage is 20ms, and the calculated effective values are sequentially stored in the cache array Uo

[50] . After each storage, the array subscript is incremented by 1. When the array subscript reaches 49, the array subscript is reset to 0;

[0049] (3) The master station periodically sends polling messages to the slave station. Denote the moment when the master station finishes sending the polling message as A. At moment A, the master station immediately calculates the average value of the 50 effective voltage values in the buffer array Ui

[50] to obtain the average value Ui of the incoming line voltage within 1 second before moment A. After the master station finishes sending the message, it waits for the slave station to reply with a message.

[0050] (4) Denote the moment when the master station finishes receiving the slave station's polling message as B. At moment B, the slave station immediately calculates the average value of the 50 effective voltage values in the buffer array Uo

[50] to obtain the average value Uo of the load side voltage within 1 second before moment B. And in the reply message from the slave station to the master station this time, add the average value Uo of the load side voltage calculated by the slave station this time.

[0051] (5) After the master station receives the reply message from the slave station, it parses and obtains the average value Uo of the load side voltage this time. Then the master station performs a difference operation on the average value Uo of the load side voltage this time and the average value Ui of the incoming line voltage this time to obtain the voltage difference ΔU between the incoming line side and the load side this time.

[0052] (6) The master station compares the voltage difference ΔU between the incoming line side and the load side this time with the preset over - tolerance fault alarm threshold ΔUset. If ΔU > ΔUset, then give a fault alarm prompt; otherwise, if ΔU ≤ ΔUset, then cancel the fault alarm prompt.

[0053] (7) Wait for the next polling cycle and repeat steps (3) to (6).

Claims

1. A load side voltage monitoring module, used to monitor the load side voltage of a transfer switch, characterized in that: include: A load-side voltage detection unit, used to collect a voltage signal on the load side of the transfer switch; A microprocessor unit, used for calculating the load side voltage according to the load side voltage signal of the transfer switch provided by the load side voltage detection unit; The communication unit is used to realize data interaction between the load-side voltage monitoring module and the controller of the transfer switch.

2. The load side voltage monitoring module according to claim 1, characterized in that: The load-side voltage monitoring module can exist independently as an optional accessory of the conversion switch.

3. A transfer switch, comprising a controller capable of collecting voltage signals on the incoming line side of the transfer switch and calculating the incoming line side voltage based on the collected voltage signals; characterized in that: The controller is interactively connected with the load-side voltage monitoring module according to claim 1 or 2; the controller performs self-diagnosis of the input and output line voltages according to the following method: comparing the input line side voltage with the load side voltage provided by the load-side voltage monitoring module; if the deviation between the two is less than or equal to a preset threshold, the input and output line voltages are judged to be normal; otherwise, the input and output line voltages are judged to be out of tolerance.

4. The switch according to claim 3, characterized in that: The data interaction between the load-side voltage monitoring module and the controller of the transfer switch is based on the controller as the master station and the load monitoring module as the slave station. The master station sends polling messages to the slave station at a regular polling cycle. After receiving the polling message, the slave station immediately replies with a return message containing the load side voltage. In the self-diagnosis process of the input and output line voltages, the input line voltage used is the average value of the input line voltage in the Tx time period before the moment when the master station polling message of the current polling cycle is completed. The load side voltage used is the average value of the load side voltage in the Tx time period before the moment when the slave station polling message of the current polling cycle is completed. Tx is a preset time period.

5. The transfer switch according to claim 4, characterized in that: The voltage on the line side and the voltage on the load side are both effective values ​​of voltage.

6. The transfer switch according to claim 4, characterized in that: The data interaction between the load-side voltage monitoring module and the controller of the transfer switch is realized through bus communication.

7. The transfer switch according to claim 6, characterized in that: The bus communication is Modbus communication.

8. The transfer switch according to claim 3, characterized in that: The controller includes a function module expansion unit with multiple communication interfaces, which is used to realize data interaction between the controller and multiple expansion function modules including the load-side voltage monitoring module in sequence.

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