CN102891501B - Distributed control system of high-power current transformer - Google Patents

Abstract

The present invention provides a distributed control system for high-power converters, which is composed of multiple single-set controllers. Among the multiple single-set controllers: one main controller is responsible for communicating with the main Control interaction, cooperate with the main control of the wind turbine to achieve the purpose of tracking the maximum wind energy of the wind turbine, and realize the normal power generation of the wind turbine; monitor various states of the converter in real time; built-in test program, cooperate with the test work of the converter before leaving the factory; cooperate with other sub-controllers Collaborative work. The number of sub-controllers depends on the number of parallel unit modules of the converter, and the configuration of each sub-controller is exactly the same, responsible for monitoring the basic unit of the converter and sending the collected signals to the main controller of the converter , and accept the control command of the main controller to control the basic unit of the converter to complete the control of the converter. The invention can realize the independent and redundant control of the multi-module parallel units of the high-power converter, and has the advantages of small size, low cost, strong maintainability, high redundancy and the like.

Description

A Distributed Control System of High Power Converter

technical field

The invention relates to a converter control system, in particular to a control system for distributed control of a high-power converter, which is suitable for a high-power parallel converter system.

Background technique

As the brain of the converter, the controller is a particularly important part of the control system. At present, the controllers widely used in the field of high-power converters are mostly centralized, that is, signal collection, fault status indication, PWM wave generation and protection, etc. are concentrated in a set of controllers. However, in order to realize a high-power converter, it is necessary to consider the parallel operation of multiple power modules. At this time, if a centralized controller is still used, the wiring in the cabinet is complicated, and the problems of wiring shielding and cable length are not handled well, which will cause A big hidden danger. Here, a distributed control architecture is adopted, information collection and control are carried out locally, and the control unit adopts high-speed optical fiber communication, so as to achieve the purpose of real-time control.

After retrieval, the Chinese utility model patent with publication number 201869150U discloses a wind turbine control device based on DSP, MCU and FPGA, including a digital signal processor DSP, a micro control unit, and a programmable logic device The array FPGA, the analog input module is connected to the micro control unit MCU through the filter circuit and the A/D conversion module; the input and output interface and the fault feedback module are connected to the programmable logic device array FPGA through the signal isolation processing module; The micro control unit MCU is connected with the digital signal processor DSP, and the programmable logic device array FPGA is connected with the PWM signal output module.

The Chinese invention patent with the publication number 102510092A discloses a distributed real-time control unit for wind power converters, which is characterized in that the sampling board on the machine side, the sampling board on the grid side and the DC sampling board are installed at the sampling point of the power loop nearby. Realize nearby sampling, convert the analog quantity into digital quantity through the AD converter and transmit it to the controller in serial mode through the optical fiber, and receive the hardware protection threshold value and control command information sent by the controller at the same time; the power unit installed on the machine network side The power control board receives the pulse signal sent by the controller, performs serial-to-parallel conversion and pulse protection processing, and sends it to the power element to realize the control of the converter. At the same time, it samples the phase current and temperature signal of the power unit in real time, and converts it into a digital signal through the AD converter. The signal is then sent to the controller in serial.

However, none of the above technologies can realize the distributed independent control of the high-power, multi-module parallel wind power conversion system, and the developed controller is not universal and has poor scalability.

Contents of the invention

In view of the defects in the prior art, the object of the present invention is to provide a distributed control system for high-power converters, which can realize independent and redundant control of multi-module parallel units of high-power converters, and has the advantages of small size , low cost, strong maintainability, and high redundancy.

To achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

A distributed control system for high-power converters, which is composed of multiple single-set controllers, and the information interaction between multiple single-set controllers is completed through POWERLNK (high-speed communication); the multiple single-set controllers middle:

The number of the main controller is 1, which is the brain of the converter, receiving status information of each part and conveying control commands. It is firstly responsible for the interaction with the main control of the fan. It communicates with the main control of the fan through CANOPEN, sends information such as the status of the converter and the speed of the fan to the main control of the fan, and accepts the control of the main control of the fan, so as to cooperate with the main control of the fan to reach the wind turbine. The purpose of maximum wind energy tracking is to realize the normal power generation of wind turbines. Second, monitor the various states of the converters in real time. Once the converters fail or some abnormal situations occur, save the status information of these converters as a historical basis. Third, the built-in test program cooperates with the test work of the converter before leaving the factory, and the data can be transmitted to the working server in real time through Ethernet, so that the operator can monitor the working status of the converter in real time. Fourth, through POWERLNK and other sub-controllers to work together, through the data information transmitted by other sub-controllers, through the internal algorithm control process to achieve the normal operation of the converter and some abnormal fault handling.

The number of sub-controllers depends on the number of converter parallel unit modules, and the configuration of each sub-controller is exactly the same. It is first responsible for monitoring the basic unit of the converter, including back-to-back (BACK TO BACK) converters, control signals and status information of charging and unloading circuits, PWM pulse signal generation, rapid overcurrent and overheating protection, collecting voltage and current signals, and Fast protection via these signals. Secondly, the collected voltage, current, temperature and other signals are sent to the main controller of the converter through the POWERLNK communication circuit, and the control command of the main controller is accepted to control the basic unit of the converter to complete the control of the converter.

Preferably, each single set of controllers is assembled from different sub-boards according to their respective functions, and these sub-boards include BP board (bottom board), CPU board (controller board), PWR board (power board), OP board (fiber optic board), PEBB board (power module board), DIO board (digital input and output board), QEP board (encoder interface board).

Preferably, the main controller includes a BP board, a PWR board, a CPU board, an OP board, a PEBB board, a DIO board, and a QEP board, wherein:

The BP board is used to indicate various operating states of the main controller, and connects each sub-board (PWR board, CPU board, OP board, PEBB board, DIO board) through the AMP plug-in; in addition, the BP board bottom board itself has an optical fiber Transceivers that can be used to communicate with other controllers.

The PWR board is used for the power supply of each control sub-board in the main controller, the input terminal is connected to +24V DC power supply, and the output +5V DC power is supplied to each sub-controller board through the BP board.

The CPU board is connected to the BP board through the AMP plug-in, and the ARM in the board handles some parameter settings, program update, fault data recording, human-computer interaction, etc., and the DSP in the board is responsible for complex control algorithms. The digital interface between each sub-board and BP board is completely realized through FPGA modular design, which realizes sending the data uploaded by each sub-controller to DSP, and sending the command information sent by DSP to each sub-controller.

The OP board has the function of transmitting and receiving optical fiber data, and is connected to the base plate through the AMP plug-in, and the optical fiber transmitting and receiving ports are respectively connected between the main controller and the sub-controller, and are used for optical fiber communication between the two controllers.

The PEBB board is used for the acquisition of external analog signals, and converts the analog signals into digital signals for reading by FPGA on the CPU board in the main controller; For pulse signals, the PEBB board is also connected to the BP board through the AMP plug-in.

The DIO board is connected to the BP board through the AMP plug-in, reads the input digital input signal through the FPGA on the CPU board, and outputs the digital output signal sent by the CPU.

Described QEP board is used for the collection of encoder A, B, Z signal, and this board needs 24V direct current power supply, and the 24V that it outputs provides encoder, and the A, B, Z signal after shaping, filtering is received On the three analog signal acquisition interfaces on the PEBB board, it is used for CPU reading and speed calculation.

Preferably, the sub-controller includes a BP board, a PWR board, a CPU board, and a PEBB board, wherein: the two sub-boards of the BP board and the PWR board in the sub-controller have the same functions as those in the main controller;

The CPU board is connected to the BP board through the AMP plug-in. This board only uses the FPGA function part, and is responsible for sending the analog signal collected by the sub-controller PEBB board to the OP board of the main controller through the communication port of the BP board. , and at the same time receive the control information sent by the main controller for the control of the PEBB board in the sub-controller;

The PEBB board is used for the acquisition of external analog signals, and converts the analog signals into digital signals for reading by the FPGA on the CPU board in the sub-controller; it also accepts the pulse signal sent by the FPGA to generate the on-off of the drive switch tube. For pulse signals, the PEBB board is also connected to the BP board through the AMP plug-in.

Compared with the prior art, the present invention has the following beneficial effects:

1) Realized the distributed control of wind power conversion system with high power and multi-module parallel connection;

2) Free allocation of tasks between the main controller and sub-controllers can reduce the workload of a single controller system;

3) The configuration of the sub-controllers is exactly the same, and can be freely assembled according to the required functions; a single sub-board is independent of each other, and can be replaced in time if a failure occurs, making the design more flexible.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 is the structural representation of CPU board in the embodiment;

Fig. 2 is a schematic structural diagram of a distributed control system;

Figure 3 is a schematic diagram of the parallel operation topology of the 4-way converter system;

Figure 4 is a schematic diagram of the operating topology of the 1-way converter system;

Fig. 5 is the steady-state operation waveforms of the grid-side converter and the machine-side converter in the embodiment.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Example 1:

As shown in Figure 3, this embodiment is a parallel operation system of 4-way converter system, the motor is a squirrel-cage asynchronous generator, and the converter system is composed of 4 sets of back-to-back three-phase PWM converter units connected in parallel with a common DC bus. The rated power of each unit is 750kw, and the rated line voltage of the grid is 690V/50Hz.

The parallel connection of three-phase PWM converter units with a common DC bus means that several independent three-phase converter units share a common DC bus, and the AC bus is connected at the port of the three-phase system. This scheme has higher redundancy and reliability. Each set of back-to-back three-phase PWM converter units includes a machine-side filter L, a machine-side PWM converter, a DC bus capacitor bank C _d , a grid-side PWM converter, and a grid-side LCL filter. The DC motor is used to drive the squirrel cage asynchronous generator to rotate and make it rotate to generate electricity. The machine-side converter works in the PWM rectification state, which can control the speed of the squirrel-cage asynchronous generator to make it work in a constant speed mode. The DC bus capacitor plays the role of stabilizing the bus voltage and filtering. The grid-side converter works in the inverter state and is connected to the grid through the LCL filter. Among them, the LCL filter includes grid-side inductance L _g , intermediate filter capacitor C _f , and converter-side inductance L _i , and the output LCL filter functions to filter high-frequency harmonics.

As shown in Figure 2, the distributed control system is composed of 1 main controller and 4 sub-controllers, wherein the main controller consists of BP board, PWR board, CPU board, OP board, PEBB board, DIO board, QEP board composition. It is responsible for collecting the line voltage of the power grid, the DC bus voltage, the closing of the contactor switch, and the speed measurement of the motor encoder. The control algorithm is completed in the CPU of the controller, and the calculated duty cycle information is transmitted to the four sub-controllers through communication.

In this embodiment, the BP board in the main controller is used to connect each sub-board so that they can work together, that is, the PWR board, the CPU board, the OP board, the PEBB board, the DIO board, and the QEP board. The PWR board is responsible for the power supply of these sub-boards when they work normally. The PEBB board is used to collect the line voltage of the grid, the DC bus voltage and the encoder signal processed by the QEP board. These analog signals are received by the OP board together with the sub-controller below. The sent data is processed by the FPGA in the CPU board and then sent to the DSP for real-time calculation of the control algorithm. The CPU transmits the calculated command for controlling the closing of the contactor through the DIO board, and sends the duty cycle information for controlling the work of the following four sub-controllers through the sending end of the OP board.

In this embodiment, there are 4 sub-controllers in total, and each converter corresponds to 1 sub-controller. The sub-controller is composed of BP board, PWR board, CPU board, and PEBB board. The sub-controller collects the voltage and current signals in each converter cabinet, and sends the information to the main controller through the optical fiber communication of the BP board. The information is used for the control of the algorithm; at the same time, the sub-controllers receive the duty cycle information sent by the main controller, and form their own PWM waves to control the switching tubes of the converter.

In this embodiment, the BP board in the sub-controller is used to connect two sub-boards so that they can work together, that is, the PWR board, the CPU board, the OP board, and the PEBB board. The PWR board is responsible for the power supply of these sub-boards when they work normally. The PEBB board is used to collect analog signals such as voltage and current in the current transformer cabinet. After processing by the FPGA in the CPU board, they are sent through the optical fiber transmission port of the BP board. To the receiving end of the OP board of the main controller above, the information is used for the control of the algorithm; at the same time, the optical receiving end of the BP board in the sub-controller is responsible for receiving command information such as duty cycle sent from the sending port of the OP board of the main controller, After the CPU board of the sub-controller reads these data, it generates respective PWM pulse waves through the PEBB board to control the work of the corresponding current transformer.

As shown in Figure 1, in this embodiment, the biggest feature of the CPU board described is multi-CPU cooperative work, and the OMAP-L137+DSP6747 control platform is selected for design, wherein the OMAP-L137CPU adopts dual cores, including an ARM and DSP6747 floating Point CPU. Among them, ARM mainly handles some parameter settings, as well as program update, fault data acquisition, human-computer interaction, testing, etc. These are some slow applications relative to the real-time control of the converter, which can be organized through the LINUX operating system running in ARM manage. This can improve development efficiency and better organize these tasks. For DSP6747 core is mainly the part of the control algorithm, using its strong computing power, it can adapt to more complex control algorithms. The FPGA (on the CPU board) adopts Xilinx Spartan-3A series FPGA, and the digital interface with the backplane is completely realized through the FPGA modular design; CPLD is used as some peripheral control and the cooperative control of CPU and FPGA. Communication uses 100M/10M full-duplex and half-duplex Ethernet, and UART is used as a configuration extension.

In this embodiment, the BP board is integrated with an LED board, which can indicate various operating states of the controller (normal power supply, operation, stop, fault, etc.), and the bottom board is connected to each control sub-board through an AMP plug-in, which is convenient for expansion; in addition The backplane itself has fiber optic transceivers that can be used to communicate with the main module controller.

In this embodiment, the PWR board has two 24VDC redundant power supply functions, and the input and output are electrically isolated; in addition, the power board has a low-voltage monitoring function, and when the input voltage is <16VDC, the power supply low-voltage monitoring signal is activated.

In this embodiment, the OP board has 6 groups of optical fiber transceiver modules, and supports a stacked design of 3 groups of OP boards at most.

In this embodiment, the PEBB board supports the SEMIKRON GB module half-bridge driver board (applied to high-power occasions), the GD module 3-phase bridge arm driver board (applied to medium-power occasions), and is equipped with the Break module The drive interface is compatible with 3-phase 4-wire applications if Break is not used, and can be used in converter controllers for various applications; in addition, it has fast current protection, and the current protection threshold can be designed in the form of software; With fault monitoring, through multiple IO signal lines, the overvoltage, overcurrent and overheating protection signals are collected, and the driving pulse is quickly turned off to achieve the effect of fast protection.

In this embodiment, the DIO board has a 16-bit digital input and an 8-bit digital output signal; it supports a stacked design of up to 3 groups of DIO boards; through optocoupler isolation, common mode interference is reduced, and the anti-interference performance of the controller can be improved.

In this embodiment, the QEP board supports the collection of differential signals of encoders A, B, and Z, and can provide 24V power supply for encoders; through optocoupler isolation, common mode interference can be reduced, and the anti-interference performance of the controller can be improved .

Example 2:

As shown in Figure 4, in this embodiment, the single-circuit converter system operates independently, and the motor is a squirrel-cage asynchronous generator. The line voltage is 690V/50Hz. The PWM converter on the machine side operates as a PWM inverter, and the squirrel-cage generator works in electric mode. The energy flows from the grid to the DC bus capacitor, and then to the alternator. The DC bus capacitor bank C _d in the back-to-back three-phase PWM converter unit is used to stabilize the bus voltage and filter, the grid-side converter works in the rectification state, and the grid side uses LCL third-order filters to filter out high-frequency harmonics role. Wherein, the LCL filter includes a grid-side inductance L _g , an intermediate filter capacitor C _f , and a converter-side inductance L _i .

In this embodiment, the distributed controller is composed of a main controller and a sub-controller, wherein the main controller consists of a BP board, a PWR board, a CPU board, an OP board, a PEBB board, a DIO board, and a QEP board composition. It is responsible for collecting the line voltage of the power grid, the DC bus voltage, the closing of the contactor switch, and the speed measurement of the motor encoder. The control algorithm is completed in the CPU of the controller, and the calculated duty cycle information is transmitted to the sub-controller through communication.

In this embodiment, the working principles and structures of the sub-boards included in the main controller are the same as those in Embodiment 1, and will not be described in detail.

In this embodiment, there is only one sub-controller, corresponding to the control of the converter 1 . The sub-controller is composed of BP board, PWR board, CPU board, and PEBB board. The sub-controller collects the voltage and current signals in the cabinet 1 of the converter, and sends the information to the main controller through the optical fiber communication of the BP board. It is used for the control of the algorithm; at the same time, the sub-controller receives the duty cycle information sent by the main controller, and forms a PWM wave to control the switching tube of the converter.

In this embodiment, the working principle and structure of each sub-board included in the sub-controller are the same as those in Embodiment 1, and will not be described in detail again.

In the above embodiment, when the input AC380V/50Hz, the grid-side converter is equipped with an LCL filter (filter parameters: L _g is 80 μH, intermediate filter capacitor C _f is 466 μF, and converter-side inductance L _i is 170 μH) Next, the DC bus voltage is DC600V. In the case of closed-loop speed, the asynchronous generator is controlled to operate as a motor, and the corresponding experimental waveform is shown in Figure 5. It can be seen from the experimental waveform that by using this distributed control system, the motor speed can be controlled to run at 300r/min, the DC bus voltage is stable at the given value of 600V, and the system works well.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims (4)

1. a high-power converter dcs, is characterized in that being combined by a plurality of single cover controllers, and the information interaction between a plurality of single cover controllers completes by POWERLNK; In described a plurality of single cover controller:

The quantity of main controller is 1, and it is the brain of current transformer, accepts the state information of various piece and passes on control command; First it be responsible for blower fan master control mutual, by CANOPEN and blower fan master control, contact, the state of current transformer and blower fan information are sent to blower fan master control, and accept the control of blower fan master control, thereby coordinate blower fan master control to reach the object that blower fan maximal wind-energy is followed the tracks of, realize blower fan normal power generation; Its two, monitor in real time the various states of current transformer, once current transformer breaks down or some abnormal conditions occur reviewing foundation by preserving the state information of these current transformers as history; Its three, built-in testing program, coordinates current transformer test job before dispatching from the factory, and in real time data is passed on workspace server, so that operating personnel monitor current transformer working condition in real time by Ethernet; Its four, by POWERLNK and other sub-controller collaborative works, the data message transmitting by other sub-controllers, the normal work and some failure exceptions that by inner algorithm control flow, reach current transformer are dealt with the work;

The quantity of sub-controller according to the quantity of current transformer unit module in parallel number determine, and the configuration of each sub-controller is just the same; First it be responsible for monitoring current transformer elementary cell, the control signal and the state information that comprise back-to-back converter, charging, relief circuit, pwm pulse signal produces, quick overcurrent and overheating protection, gathers voltage and current signal, and protects fast by these signals; Secondly, the voltage collecting, electric current, temperature signal are sent to current transformer main controller by POWERLNK order circuit, and the control command of accepting main controller controls current transformer elementary cell, complete the control of current transformer;

Described master controller comprises BP plate, PWR plate, CPU board, OP plate, PEBB plate, DIO plate, QEP plate, wherein:

Described BP plate is used to indicate the various running statuses of master controller, and connects each daughter board by AMP plug-in unit, and expansion is convenient; In addition, BP plate base plate itself has fiber optical transceiver, for communicating by letter with other controllers;

Described PWR plate is respectively controlled the Power supply of daughter board for main controller, input termination+24V DC power supply, and output+5V direct current, needs the place of 5V to power by BP plate to each sub-controller plate;

Described CPU board is connected with BP plate by AMP plug-in unit, and the ARM in this CPU board processes some setting parameters, and program updates, fault data admission and man-machine interaction work, and the DSP in this plate is responsible for complicated control algolithm; The digital interface of each daughter board and BP plate realizes by FPGA modularized design completely, and the main data that each sub-controller is uploaded that realize send to DSP, and the command information that DSP is sent sends to each sub-controller;

Described OP plate has fiber data transmission-receiving function, by AMP plug-in unit, is connected with BP plate, and optical fiber transceiving mouth is connected between master controller and sub-controller, for the optical-fibre communications between two controllers;

Described PEBB plate is for the collection of external analog signal, and analog signal is converted to digital signal for the FPGA in master controller CPU board, reads; It also accepts the pulse signal of the pulse signal genration driving switch pipe break-make of FPGA transmission, and PEBB plate is connected with BP plate by AMP plug-in unit equally;

Described DIO plate is connected with BP plate by AMP plug-in unit, read the digital input signals that is input into, and the digital output signal that CPU is sent output comes by the FPGA in CPU board;

Described QEP plate is for the collection of encoder A, B, Z signal, this plate needs 24V DC power supply, the 24V of its output offers encoder, and shaping, filtered A, B, Z signal are received on the collection of simulant signal interface on PEBB plate, for reading with rotating speed of CPU, calculates.

2. high-power converter dcs according to claim 1, is characterized in that, described sub-controller comprises BP plate, PWR plate, CPU board, PEBB plate, wherein:

Described BP plate is used to indicate the various running statuses of master controller, and connects each daughter board by AMP plug-in unit; In addition, BP plate itself has fiber optical transceiver, for communicating by letter with other controllers;

Described PWR plate is respectively controlled the Power supply of daughter board for main controller, input termination+24V DC power supply, and output+5V direct current, needs the place of 5V to power by BP plate to each sub-controller plate;

Described CPU board is connected with BP plate by AMP plug-in unit, this CPU board has only been used FPGA funtion part, the responsible analog signal amount that sub-controller PEBB plate is collected is sent on the OP plate of master controller by the communication port of BP plate, receive master controller simultaneously and send the control information of getting off, for the control of sub-controller PEBB plate;

Described PEBB plate is for the collection of external analog signal, and analog signal is converted to digital signal for the FPGA in sub-controller CPU board, reads; It also accepts the pulse signal of the pulse signal genration driving switch pipe break-make of FPGA transmission, and PEBB plate is connected with BP plate by AMP plug-in unit equally.

3. high-power converter dcs according to claim 1 and 2, is characterized in that, described OP plate has 6 groups of optical fiber receiver-transmitter modules, supports at most 3 groups of OP plate stack design.

4. high-power converter dcs according to claim 1 and 2, is characterized in that, described DIO plate has 16 bit digital inputs, and 8 bit digital output signals, support at most 3 groups of DIO plate stack design.