CN201742094U - Intelligent CAN bus voltage reactive power compensation device - Google Patents

Abstract

A CAN bus voltage and reactive power intelligent compensation device, including a host computer that monitors and manages the entire system, the host computer is connected to the CAN bus through its internal CAN interface adapter card, and multiple CAN buses are connected to the CAN bus A network node, the CAN network node includes a microcontroller, the microcontroller is equipped with a CAN controller and a CAN transceiver, and the microcontroller is connected with a power sensor and a switching capacitor for grid parameter collection. The beneficial effects of the utility model: use the intelligent node unit to feed back the real-time data to the microcomputer, know the reactive power compensation information of each terminal in time, and realize the intelligent management of the reactive power compensation by checking the historical data; It has the advantages of small grid surge current when the capacitor is zero switched, and the advantage of no power consumption and energy saving of the thyristor when the contactor is closed. At the same time, it can also centrally manage multiple reactive power compensation nodes to realize data sharing.

Description

A CAN bus voltage and reactive power intelligent compensation device

technical field

The utility model relates to a voltage and reactive power intelligent compensation device based on CAN (Controller Area Network) field bus in the field of power distribution. the

Background technique

With the development of my country's national economy, the production and transmission of electric energy are more and more closely related to people's production. Under normal circumstances, electrical equipment not only needs to obtain active power from the power supply, but also needs to obtain reactive power from the power supply. Reactive power reduces the power supply capacity of power transmission and transformation equipment, resulting in increased line voltage loss and power loss, resulting in low power factor operation and voltage drop, so that the capacity of electrical equipment cannot be fully utilized. In the power distribution system, the natural power factor of most electrical equipment is around 0.7, that is, 50% of the network loss in the power distribution system is caused by reactive power. If the reactive power of the power distribution system is compensated, the power distribution The network loss of the system can be reduced by 50%, and the loss of the entire power grid can be reduced by 35%, which has great energy-saving benefits. In order to reduce losses and save energy, improve the power factor of the power grid, and ensure voltage stability, the power sector has vigorously promoted in-situ reactive power compensation devices, especially reactive power compensation at low voltage 380V has become a research hotspot in recent years. the

The traditional reactive power compensation device realizes switching of the capacitor bank by controlling the AC contactor or air switch. The fatal weakness of this device is that the action speed of the mechanical contact does not match the change speed of the power frequency voltage and current. Due to the existence of the polarity of the capacitor, inrush current will inevitably be generated. When the inrush current impact is severe, the arc will re-ignite and cause overvoltage or overcurrent to break down the electric heater. Later, the commonly used thyristor switching trigger circuit switched capacitors to realize reactive power compensation to the power grid, which could alleviate this contradiction to a certain extent. If the capacitor is not switched at the moment of zero crossing, due to the capacitor discharge time and residual voltage problems, the capacitor will be burned in actual engineering. Later, people combined the thyristor with the conventional contactor switch to form a composite switch, which solved the inrush current impact when switching capacitors, and protected the capacitors to a certain extent, but this technology also has its limitations. Single-node compensation leads to data failure. Sharing and centralized control, especially when the electrical equipment is scattered and multiple reactive power nodes are required for compensation, this contradiction is even more prominent. At the same time, it is also necessary to improve the traditional reactive power composite switch compensation technology to make it safer and more reliable. sex. the

Contents of the invention

Aiming at the problems existing in the application of reactive power compensation devices of traditional electromagnetic switches and power electronic switch switching capacitors, the utility model provides a CAN bus voltage reactive power intelligent compensation device. the

The technical scheme of the utility model:

A CAN bus voltage and reactive power intelligent compensation device is characterized in that: it includes a host computer that monitors and manages the entire system, the host computer is connected to the CAN bus through its internal CAN interface adapter card, and the CAN bus is connected to There are a plurality of CAN network nodes, and the CAN network nodes include microcontrollers, the microcontrollers are equipped with CAN controllers and CAN transceivers, and the microcontrollers are connected with power sensors and switching capacitors for grid parameter collection . the

Further, a photoelectric isolator is provided between the CAN controller and the CAN transceiver. the

Further, the CAN network nodes are connected to the CAN bus in a distributed structure. the

Further, the switched capacitor is a composite switch switched capacitor. the

Further, the microcontroller is also externally connected with buttons for parameter setting and calling, an LCD display for parameter display, a watchdog and an alarm device. the

Further, the host computer is equipped with a printer. the

The number of CAN network nodes of the utility model can be increased or decreased according to the scale of the power grid, and the CAN bus is used as a communication network to connect each node into a distributed intelligent control system. The network topology adopts the bus structure, and the passive tap connection is adopted, so the system reliability is high. The CAN bus is selected to connect each network node to form a multi-host controller local area network. The information transmission adopts CAN communication protocol, and the transmission medium adopts twisted pair wire. In order to further improve the anti-interference ability of the system, a photoelectric isolation is added between the controller and the transmission medium. In the intelligent node, in order to realize the turn-on and turn-off control of the composite switch, improve its anti-interference ability, and can be used in conjunction with a variety of different AC contactors or high-power relays, this device proposes an 89C52 single-chip microcomputer As the core bus-type intelligent composite switch, it integrates field communication technology and composite switch technology. the

Working principle: The upper computer is connected to the CAN bus through the CAN interface adapter card for information exchange, and equipped with a printer to monitor and manage the entire system. The CAN network node microcontroller receives various operation control commands and setting parameters from the upper computer through the CAN bus, and collects the voltage, current, reactive power, active power, capacitor switching and other signals in the power grid in real time through the power sensor. CAN network nodes can transmit various parameters with the monitoring station and other CAN network nodes, and receive commands and data from the monitoring station to adjust and change the control state. Through the calculation of the microcontroller, when the detected power factor deviates from the normal value, the capacitor is switched on and off through the compound switch to ensure that the capacitor is switched on when the voltage crosses zero, and cut off when the current crosses zero, realizing an adaptive thyristor trigger Switching can also improve the dynamic response speed when the capacitor is switched. At the same time, the data is uploaded to the upper computer, and the upper computer performs centralized data processing and management. the

The beneficial effects of the utility model:

1. Use the intelligent node unit to feed back the real-time data to the microcomputer to know the reactive power compensation information of each terminal in time, and realize the intelligent management of reactive power compensation by viewing the historical data. the

2. Compared with the traditional contactor and thyristor switched capacitor (TSC) system, this device mainly has the advantages of small power grid surge current when the thyristor crosses zero and switches the capacitor, and the reactive power of the thyristor when the contactor is closed. It has the advantages of energy consumption and energy saving. At the same time, it can also centrally manage multiple reactive power compensation nodes to realize data sharing. the

Description of drawings

Fig. 1 is the overall structural representation of the utility model. the

Fig. 2 is a schematic structural diagram of the CAN network node of the present invention. the

Fig. 3 is a schematic wiring diagram of the composite switch of the present invention. the

Detailed ways

Referring to Figures 1-3, a CAN bus voltage and reactive power intelligent compensation device includes a host computer 1 that monitors and manages the entire system, and the host computer 1 is connected to the CAN bus 4 through its internal CAN interface adapter card 3, A plurality of CAN network nodes 5 are connected on the CAN bus 4, and the CAN network nodes 5 include a microcontroller 15, and the microcontroller 15 is equipped with a CAN controller 9, a CAN transceiver 11, and the microcontroller 15 is connected with a power sensor 6 and a switching capacitor 7 for grid parameter collection. the

A photoelectric isolator 10 is provided between the CAN controller 9 and the CAN transceiver 11 . the

The CAN network node 5 is connected to the CAN bus 4 in a distributed structure. the

The switched capacitor 7 is a composite switch switched capacitor. the

The microcontroller 15 is also externally connected with buttons 8 for parameter setting and calling, an LCD display 12 for parameter display, a watchdog 14 and an alarm device 13 . the

The host computer 1 is equipped with a printer 2 . the

The transmission medium of this embodiment adopts twisted pair, and when the communication rate is set to 200Kb/s, the distance between any two nodes of the CAN bus 4 can reach 3.3km, which can fully meet the compensation control requirements of the power consumption local area network. The upper computer is connected to the CAN bus through the CAN interface adapter card 3 for information exchange, and is equipped with a printer 2 to monitor and manage the entire system. The CAN intelligent network node microcontroller 15 receives various operation control commands and setting parameters of the upper computer through the CAN bus, and collects signals such as voltage, current, reactive power, active power, and capacitor switching in the power grid in real time through the power sensor 6 . The CAN network node 5 can transmit various parameters with the monitoring station and other CAN network nodes 5, and receive commands and data from the monitoring station to adjust and change the control state. Through the calculation of the microcontroller 15, when the detected power factor deviates from the normal value, the capacitor 7 is switched on and off through the composite switch to ensure that the capacitor is switched on when the voltage crosses zero, and cut off when the current crosses zero, realizing an adaptive Thyristor trigger switching can also improve the dynamic response speed of capacitor switching. At the same time, the data is uploaded to the upper computer, and the upper computer performs centralized data processing and management.

CAN network node 5 is mainly made up of CAN communication controller SJA1000, photoelectric isolator 6N137, CAN bus transceiver 82C250, single-chip microcomputer system, electric quantity sensor etc. in the present embodiment, and master controller is AT89C52 single-chip microcomputer system 15, and external connection is used for the setting of parameter And call button 8, LCD display screen 12 for parameter display, sensor 6 for grid parameter collection, execution structure for composite switch switching capacitor 7, used for single-chip microcomputer system that may appear due to external interference Watchdog X5045 for safety protection of "running away" or crash, and alarm device 13 for early warning of abnormal system conditions. The working principle is: the current and voltage signals sent from the control site sensors CT and PT are processed to make the input voltage and current signals meet the input requirements of the data acquisition and measurement chip SA9904B. SA9904B stores the measured three-phase power parameters related values such as voltage, active energy, reactive energy, frequency, etc. in its internal register. Single-chip microcomputer accesses the 24-bit temporary register inside SA9904B through the SPI interface, calculates the data of the temporary register according to the corresponding formula to obtain the active power and reactive power of each phase, and controls the compound switch to switch according to the preset control strategy. Cut the capacitor, and at the same time send the relevant data to the CAN bus in the form of a frame, and can also receive the relevant commands sent by the host computer. the

The principle wiring of the composite switch is shown in Figure 3. The main controller MCU sends a switching signal 16 according to the reactive power compensation control strategy. When there is a switching signal 16, the optocoupler MOC3081 detects and judges and controls the thyristor 18 to trigger the circuit. The optocoupler 17 chip designs an advanced voltage zero-crossing trigger circuit, and uses a voltage zero-crossing optocoupler bidirectional thyristor to replace the driving links such as power amplifier circuits and pulse transformers composed of discrete components, which simplifies the structure of the trigger control circuit. The advantage of this circuit is that its circuit is simple and easy to implement, and it can accurately capture the moment of the first zero crossing of phase A, and then can determine the time of each zero crossing of phase A, and issue a series of control commands. the

The basic working principle of the composite switch is: connect the thyristor switch 18 and the contactor 22 in parallel to realize zero-crossing conduction of voltage and zero-crossing current cut-off, so that the composite switch has the function of zero-crossing switching of the thyristor switch at the moment of turning on and off. Advantages, and has the advantage of no power consumption of the contactor switch during normal turn-on. The realization method is: when the voltage is zero, the thyristor first triggers when the voltage crosses zero, and then the contactor is turned on after it is stable; when it is cut out, the contactor is disconnected first, and the thyristor is delayed and disconnected when it crosses zero. So as to realize the current zero-crossing cut-off. Since the thyristor only works at the moment of turning on and off, and the main closing time is the contactor, so the composite switch has the advantages of both the thyristor and the contactor, and at the same time avoids the disadvantages of both. the

In the single-phase composite switch, when the A-phase capacitor 21 is to be put into operation, the operation sequence of each switch is: first, switch K2 is turned on, and when the voltage of the A-phase crosses zero, the thyristor is turned on; the second step is to turn on the switch K1 ; The third step, when the phase A current is zero, disconnect the thyristor; finally disconnect the switch K2. In this way, the capacitor C is put into operation, and when it is necessary to cast another set of capacitors, the operation is also performed in the same order. When the capacitor C is to be cut off, the sequence of the switches is basically the same as above, except that the second step of closing the switch K1 is changed to disconnecting the switch K1. In this way, the capacitor C is removed from the system, and other capacitors to be removed also follow this procedure. The control process of the three-phase composite switch is similar to that of the single-phase composite switch, and will not be described in detail. the

The content described in the embodiments of this specification is only an enumeration of the realization forms of the utility model concept, and the protection scope of the utility model should not be regarded as being limited to the specific forms stated in the embodiments, and the protection scope of the utility model is also As well as the equivalent technical means that those skilled in the art can think of according to the concept of the utility model. the

Claims (6)

1. A kind of CAN bus voltage reactive power intelligent compensation device, it is characterized in that: comprise the host computer that whole system is monitored and managed, described host computer is connected with CAN bus by its internal CAN interface adapter card, described CAN bus A plurality of CAN network nodes are connected to the network, and the CAN network nodes include a microcontroller, the microcontroller is equipped with a CAN controller and a CAN transceiver, and the microcontroller is connected with a power sensor for grid parameter collection, a power input Cut the capacitor. 2. A kind of CAN bus voltage reactive power intelligent compensation device according to claim 1, characterized in that: a photoelectric isolator is arranged between the CAN controller and the CAN transceiver. 3. A kind of CAN bus voltage and reactive power intelligent compensation device according to claim 1 or 2, characterized in that: the CAN network nodes are connected to the CAN bus in a distributed structure. 4. A CAN bus voltage and reactive power intelligent compensation device according to claim 3, characterized in that: the switching capacitor is a composite switch switching capacitor. 5. A kind of CAN bus voltage reactive power intelligent compensation device according to claim 4, is characterized in that: described micro-controller is also externally connected with the button that is used for parameter setting and calling, the LCD display screen that is used for parameter display, sees Door dog and alarm device. 6. A kind of CAN bus voltage reactive power intelligent compensation device according to claim 5, characterized in that: the host computer is equipped with a printer.

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