Residual current acquisition module

Abstract

The utility model discloses a residual current acquisition module. Comprising a mainboard, the mainboard is provided with at least one multi-channel synchronous sampling chip and a micro-control unit, and each path of data input end of the multi-channel synchronous sampling chip is electrically connected with the data output end of a current acquisition unit; the data input end of each current acquisition unit is connected with the signal output end of one residual current transformer; each residual current transformer is used for being installed on a branch bus of an alternating current power supply system and collecting residual current on the corresponding branch bus. The micro-control unit is in two-way communication connection with the multi-channel synchronous sampling chip; the control signal input end of each current acquisition unit is electrically connected with the control signal output end of the micro-control unit. According to the application, the current collected by the multiple paths of residual current transformers connected with the multi-channel synchronous sampling chip can be sampled at the same time, the consistency of the performance of each path of residual current transformer can be realized, and the accuracy of the residual current measurement result is ensured.

Description

Technical Field

[0001] The present application relates to the technical field of electric power equipment, and in particular to a residual current acquisition module. Background Art

[0002] At present, the residual current monitoring of the station AC power supply system is divided into two types: online and portable. Since there are many branch buses in the station AC system, and even several sub-screens under the main screen, in order to simplify the on-site installation and facilitate wiring, the online monitoring equipment generally adopts a modular design: one host is connected to multiple acquisition modules, and one acquisition module is connected to multiple residual current transformers (CTs), such as Figure 1 shown.

[0003] For a shared N-line dual power supply circuit, the phase line and neutral line of a single circuit need to be installed with a residual current transformer circuit respectively (the phase line and neutral line of this branch cannot pass through the same CT due to on-site wiring). In the case where it is not possible to use one CT to monitor the residual current, the current synthesis of multiple CTs is generally used to complete the monitoring of the branch residual current. Figure 2 In the design, the residual current of the branch is obtained by synthesizing the currents of CT1 and CT2. Since the transformer needs to be installed according to the actual situation on site, in order to avoid adjusting the wiring when the on-site load is adjusted, the currents of multiple CTs are generally vector-synthesized to obtain the residual current of the branch.

[0004] Strictly speaking, the currents for vector synthesis should be sampled at the same time, so that the synthesized current is the residual current on this branch at that moment. The traditional acquisition module is designed based on the principle of a single CT to complete residual current monitoring, and uses the same set of circuits to sample the currents of multiple CTs in turn. Therefore, when multiple CTs are used to synthesize residual current, the accuracy of the detection results cannot be guaranteed, and it may even cause the detection device to report a false alarm:

[0005] (1) For branches that require multiple CTs to jointly complete residual current monitoring, since synchronous sampling cannot be achieved, the sampling time of each CT current is different, which affects the synthesis result;

[0006] (2) Due to the influence of factors such as core material and manufacturing process, the amplitude and phase of the output signal of each CT cannot be exactly the same (the magnetic change of any magnetic material lags behind the instantaneous value change of current, thus causing phase change). Therefore, when two or more CTs with inconsistent performance parameters are directly vector synthesized, the synthesized result will not match the actual result. Utility Model Content

[0007] To this end, the present application provides a residual current acquisition module to solve the technical problem that the existing residual current acquisition module cannot guarantee the accuracy of the detection result when used for multiple residual current transformers to synthesize residual current.

[0008] In order to achieve the above objectives, this application provides the following technical solutions:

[0009] In a first aspect, a residual current acquisition module includes a main board, on which is disposed:

[0010] At least one multi-channel synchronous sampling chip, each data input end of the multi-channel synchronous sampling chip is electrically connected to the data output end of a current acquisition unit; the data input end of each current acquisition unit is electrically connected to the signal output end of a residual current transformer; each residual current transformer is used to be installed on a branch bus of the AC power supply system to collect the residual current on the corresponding branch bus;

[0011] A micro control unit is bidirectionally connected to the multi-channel synchronous sampling chip; the control signal input end of each current acquisition unit is electrically connected to the control signal output end of the micro control unit.

[0012] Optionally, the current acquisition unit includes a follower circuit, a filter circuit, a programmable amplifier circuit and a programmable phase shift circuit. The data input end of the follower circuit is electrically connected to the signal output end of a residual current transformer. The data output end of the follower circuit is electrically connected to a data input end of a corresponding multi-channel synchronous sampling chip through the filter circuit, the programmable amplifier circuit and the programmable phase shift circuit in sequence; the control signal input end of the programmable amplifier circuit and the control signal input end of the programmable phase shift circuit are both electrically connected to a control signal output end of the micro control unit.

[0013] Optionally, the model of the multi-channel synchronous sampling chip is AD7606.

[0014] Optionally, there are two multi-channel synchronous sampling chips.

[0015] Optionally, the current collection unit is vertically inserted into the mainboard via a BTB connector.

[0016] Further optionally, the size of the current collection unit is 30 mm*17 mm.

[0017] Optionally, a communication interface is further provided on the mainboard, and the communication interface is bidirectionally connected to the micro control unit for communication, and the communication interface is used to establish a bidirectional communication connection with a host.

[0018] Further optionally, the communication interface is a CAN interface.

[0019] Compared with the prior art, this application has at least the following beneficial effects:

[0020] The embodiment of the present application provides a new hardware architecture of a residual current acquisition module, which includes a mainboard, on which are disposed at least one multi-channel synchronous sampling chip and a microcontroller unit; wherein each data input terminal of the multi-channel synchronous sampling chip is electrically connected to the data output terminal of a current acquisition unit; the data input terminal of each current acquisition unit is electrically connected to the signal output terminal of a residual current transformer; the microcontroller unit is bidirectionally connected to the multi-channel synchronous sampling chip; the control signal input terminal of each current acquisition unit is electrically connected to the control signal output terminal of the microcontroller unit; in the hardware architecture of the residual current acquisition module, on the one hand, due to the provision of a multi-channel synchronous sampling chip, the currents collected by the multiple residual current transformers connected to the multi-channel synchronous sampling chip can be sampled simultaneously, thereby ensuring that the residual current data vector synthesized by the subsequent microcontroller unit is consistent in sampling time, and ensuring On the other hand, since a separate current acquisition unit is configured for each residual current transformer, and the control signal input end of each current acquisition unit is electrically connected to the control signal output end of the microcontroller unit, when residual current sampling is performed through multiple residual current transformers connected to multiple current acquisition units, the microcontroller unit can set the parameters of each current acquisition unit so that each residual current transformer outputs a current signal with the same amplitude and the same phase when the same current flows through it, thereby achieving consistency in the performance of each residual current transformer, and making the residual current vector synthesis result in the subsequent microcontroller unit consistent with the actual one; therefore, the residual current acquisition module provides a hardware architecture contribution to solve the problem that the existing residual acquisition module cannot achieve synchronous sampling and cannot ensure the consistency of the performance of each CT, resulting in inaccurate synthesis results, thereby ensuring the accuracy of the residual current measurement result. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more intuitively illustrate the prior art and the present application, exemplary drawings are given below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing the present application; for example, those skilled in the art are capable of easily making conventional adjustments or further optimizations to the addition / reduction / attribution division, specific shapes, positional relationships, connection methods, dimensional ratios, etc. of certain units (components) based on the technical concepts and exemplary drawings disclosed in the present application.

[0022] Figure 1 It is a schematic diagram of the connection relationship of the acquisition module;

[0023] Figure 2 It is a schematic diagram of residual current synthesis;

[0024] Figure 3 A schematic diagram of the structure of a residual current acquisition module provided in an embodiment of the present application;

[0025] Figure 4 Schematic diagram of the circuit structure of the current acquisition unit in the embodiment of the present application;

[0026] Figure 5 This is a circuit diagram of 16 CT simultaneous sampling in an embodiment of the present application;

[0027] Figure 6 This is a schematic diagram of a small board of a current collection unit in an embodiment of the present application;

[0028] Figure 7 This is part of the circuit of the current acquisition module in the embodiment of the present application;

[0029] Figure 8 Another specific structural schematic diagram of a residual current acquisition module provided in an embodiment of the present application.

[0030] Description of reference numerals:

[0031] 1. Multi-channel synchronous sampling chip; 2. Current acquisition unit; 201. Follower circuit; 202. Filter circuit; 203. Programmable amplifier circuit; 204. Programmable phase shift circuit; 3. Residual current transformer; 4. Micro control unit; 5. Communication interface; 6. Host. DETAILED DESCRIPTION

[0032] The present application is further described below in detail through specific embodiments in conjunction with the accompanying drawings.

[0033] In the description of this application: unless otherwise specified, the meaning of "plurality" is two or more. The terms "first", "second", "third", etc. in this application are intended to distinguish the objects referred to, and do not have special meanings in terms of technical connotations (for example, they should not be understood as emphasizing the importance or order, etc.). Expressions such as "including", "comprising", "having", etc. also mean "not limited to" (certain units, components, materials, steps, etc.).

[0034] The terms such as "upper", "lower", "left", "right", "middle", etc. cited in this application are usually used to indicate the general relative position relationship for the purpose of intuitive understanding by referring to the drawings, and are not absolute limitations on the position relationship in the actual product.

[0035] In an embodiment of the present application, a residual current acquisition module is provided, which includes a main board, such as Figure 3 As shown, the main board is equipped with:

[0036] At least one multi-channel synchronous sampling chip (i.e., A / D sampling chip) 1, each data input end of the multi-channel synchronous sampling chip 1 is electrically connected to the data output end of a current acquisition unit 2; the data input end of each current acquisition unit 2 is electrically connected to the signal output end of a residual current transformer (abbreviated as CT) 3; each residual current transformer 3 is used to be installed on a branch bus of the AC power supply system to collect the residual current on the corresponding branch bus;

[0037] A microcontroller unit (MCU) 4 is bidirectionally connected to the multi-channel synchronous sampling chip 1 ; the control signal input end of each current acquisition unit 2 is electrically connected to the control signal output end of the microcontroller unit 4 .

[0038] In the hardware architecture of the residual current acquisition module provided in the embodiment of the present application, since a multi-channel synchronous sampling chip 1 is provided, multiple CT currents connected to the multi-channel synchronous sampling chip 1 can be sampled simultaneously, thereby ensuring that the residual current data for vector synthesis by the subsequent micro-control unit 4 is consistent in sampling time, thereby ensuring the accuracy of the synthesized results.

[0039] In addition, since in the hardware architecture of the residual current acquisition module, a separate current acquisition unit 2 is configured for each residual current transformer 3, and the control signal input end of each current acquisition unit 2 is electrically connected to the control signal output end of the micro control unit 4, when the residual current is sampled through multiple residual current transformers 3 connected to multiple current acquisition units 2, as an optional implementation, the micro control unit 4 can set the parameters of each current acquisition unit 2 so that the parameters in each current acquisition unit 2 match the corresponding residual current transformer 3; the parameters in each current acquisition unit 2 that match the corresponding residual current transformer 3, that is, when the same current flows through each residual current transformer 3, each current acquisition unit 2 outputs the parameters of the current signal with the same amplitude and the same phase. In this way, the consistency of the performance of each residual current transformer 3 can be achieved, so that the residual current vector synthesis result in the subsequent micro control unit 4 is consistent with the actual situation.

[0040] Furthermore, if Figure 4As shown, each current acquisition unit 2 specifically includes a follower circuit 201, a filter circuit 202, a programmable amplifier circuit 203 and a programmable phase shift circuit 204. The data input end of the follower circuit 201 is electrically connected to the signal output end of a residual current transformer 3, and the data output end of the follower circuit 201 is electrically connected to a data input end of a corresponding multi-channel synchronous sampling chip (A / D sampling chip) 1 through the filter circuit 202, the programmable amplifier circuit 203 and the programmable phase shift circuit 204 in sequence; the control signal input end of the programmable amplifier circuit 203 and the control signal input end of the programmable phase shift circuit 204 are both electrically connected to a control signal output end of a micro control unit 4.

[0041] That is to say, the current acquisition unit 2 includes circuits for following, filtering, program-controlled amplification, program-controlled phase shifting, etc. The amplification factor of the program-controlled amplification circuit 203 and the phase shift angle of the program-controlled phase shifting circuit 204 can be adjusted by the MCU.

[0042] Furthermore, the multi-channel synchronous sampling chip 1 adopts a 16-bit 8-channel synchronous sampling chip AD7606, which can process true bipolar input signals of ±10V and ±5V and supports a maximum throughput rate sampling of 200kSPS, which is suitable for sampling sinusoidal voltage and current in power systems.

[0043] Furthermore, the multi-channel synchronous sampling chip 1 has two. In other words, the residual current acquisition module uses two A / D chips in parallel, such as Figure 5 As shown, each A / D samples 8 channels, and completes current sampling of 16 branches at the same time, and the corresponding current acquisition units 2 have 16. That is to say, a residual current acquisition module can be connected to 16 acquisition units at most, that is, a acquisition module can monitor the residual current of 16 branches at most.

[0044] Furthermore, if Figure 6 As shown, each current acquisition unit 2 is made into a sampling board with a size of 30mm*17mm, which is vertically inserted into the main board of the residual current acquisition module through a BTB connector. The installation diagram of 16 current acquisition units 2 on the main board can be seen in Figure 7 .

[0045] Furthermore, if Figure 3 As shown, a communication interface 5 is also provided on the mainboard. The communication interface 5 is bidirectionally connected to the micro control unit 4 . The communication interface 5 is used to establish a bidirectional communication connection with the host 6 .

[0046] The communication interface 5 is specifically a CAN interface.

[0047] In other words, the present application designs a residual current acquisition module with 16 simultaneous sampling channels and capable of matching and setting the parameters of 16 CT channels. In this current acquisition module, a separate sampling board (current acquisition unit 2) is configured for each CT channel, and each sampling board is loaded with the parameters of the corresponding CT to achieve consistent adjustment of CT performance. A multi-channel synchronous sampling A / D is used to sample the 16 CT currents at the same time to ensure that the data for vector synthesis is consistent in sampling time and to ensure the accuracy of the synthesized results. In other words, Figure 8 As shown, the residual current acquisition module includes 16 current acquisition units 2, two 8-channel synchronous sampling A / Ds, an MCU microcontroller unit 4 and a CAN interface for communicating with a host 6.

[0048] The CT current acquisition unit 2 includes circuits such as following, filtering, program-controlled amplification, and program-controlled phase shifting. The parameters of the program-controlled amplification circuit 203 and the program-controlled phase shifting circuit 204 can be set by the MCU. Based on the hardware architecture of the residual current acquisition module provided in the present application, as an optional implementation method, each CT matched with the host 6 can be address-encoded before leaving the factory, and then debugged: each CT outputs a current signal with the same amplitude and phase when the same current flows through, and the parameter data of each CT obtained after debugging is made into a database and saved in the data storage device of the host 6; when the on-site installation is completed, the address code of each CT is input into the host 6, and the host 6 can read the parameters according to the address and send them to the micro-control unit 4, and then the micro-control unit 4 can adjust the gain coefficient of the program-controlled amplification circuit 203 and the phase shift angle of the program-controlled phase shifting circuit 204 in the corresponding acquisition unit of each CT according to the parameter data sent by the host 6, so that the amplification factor and phase shift angle of each acquisition unit match the CT, and ensure that the output performance of each CT is consistent after matching with the acquisition unit, so that when any CT needs to be set as synthesis on site, the accuracy of the synthesis result can be guaranteed.

[0049] During operation, when the module MCU microcontroller unit 4 receives the start detection instruction sent by the host 6, it can start all channels of the A / D chip for synchronous sampling, and save the sampling data of each CT after the sampling is completed. As an optional configuration, the branch set to be synthesized within the module is directly vector synthesized by the acquisition module MCU to obtain the residual current value of the branch; the branch set to be synthesized between modules is sent to the host 6 by the acquisition module, and the host 6 performs vector synthesis on the synthesized sampling data according to the configuration to obtain the residual current value of the branch. Monitoring of branch insulation that cannot be completed with one CT for residual current monitoring is achieved. How to perform vector synthesis specifically belongs to the common knowledge and conventional technical means of those skilled in the art, and will not be elaborated here, so this application does not involve improvements in the method.

[0050] The residual current acquisition module provided in the embodiment of the present application, by setting a multi-channel synchronous sampling chip 1 and equipping each CT with an independent current acquisition unit 2, provides a hardware architecture contribution for synchronizing the sampling time of all CTs and matching the parameters of each CT. It can monitor the insulation conditions of branches that require multiple CTs to complete residual current monitoring, improve the detection function of the residual current monitoring device of the station AC system, and do not need to change the wiring method of the on-site installation.

[0051] In summary, the residual current acquisition module provided in the embodiment of the present application has at least the following advantages:

[0052] (1) The structural design ensures synchronous sampling of each CT while maintaining the original installation size and wiring method; and greatly improves the accuracy of the synthetic data;

[0053] (2) CTs and modules can be matched arbitrarily, and the synthetic branches can be set arbitrarily according to the site conditions;

[0054] (3) The synthesis and calculation of multiple CT data within the same module can be completed independently by the module, and the synthesis of multiple CT data across modules can be completed by the host. This distributed layout can maximize the processor performance of each module, reduce the data bandwidth of the interface communication network, alleviate the computing pressure of the host, and take into account the real-time nature of the sampling data, thereby improving the refresh speed of the detection results.

[0055] The technical features of the above embodiments may be arbitrarily combined (as long as there is no contradiction in the combination of these technical features). To make the description concise, not all possible combinations of the technical features in the above embodiments are described; these embodiments that are not explicitly written should also be considered to be within the scope of this specification.

Claims

1. A residual current acquisition module, comprising a main board, characterized in that: The main board is provided with: At least one multi-channel synchronous sampling chip, each data input end of the multi-channel synchronous sampling chip is electrically connected to the data output end of a current acquisition unit; the data input end of each current acquisition unit is electrically connected to the signal output end of a residual current transformer; each residual current transformer is used to be installed on a branch bus of the AC power supply system to collect the residual current on the corresponding branch bus; A micro control unit is bidirectionally connected to the multi-channel synchronous sampling chip; the control signal input end of each current acquisition unit is electrically connected to the control signal output end of the micro control unit.

2. The residual current acquisition module according to claim 1, characterized in that: The current acquisition unit includes a follower circuit, a filter circuit, a programmable amplifier circuit and a programmable phase shift circuit. The data input end of the follower circuit is electrically connected to the signal output end of a residual current transformer. The data output end of the follower circuit is electrically connected to a data input end of a corresponding multi-channel synchronous sampling chip through the filter circuit, the programmable amplifier circuit and the programmable phase shift circuit in sequence; the control signal input end of the programmable amplifier circuit and the control signal input end of the programmable phase shift circuit are both electrically connected to a control signal output end of the micro control unit.

3. The residual current acquisition module according to claim 1, characterized in that: The model of the multi-channel synchronous sampling chip is AD7606.

4. The residual current acquisition module according to claim 1, characterized in that: The multi-channel synchronous sampling chip has two.

5. The residual current acquisition module according to claim 1, characterized in that: The current collection unit is vertically inserted into the mainboard via a BTB connector.

6. The residual current acquisition module according to claim 5, characterized in that: The size of the current collection unit is 30mm*17mm.

7. The residual current acquisition module according to claim 1, characterized in that: The mainboard is also provided with a communication interface, which is bidirectionally connected to the microcontroller unit for communication, and is used to establish a bidirectional communication connection with the host.

8. The residual current acquisition module according to claim 7, characterized in that: The communication interface is a CAN interface.

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