A power distribution and speed control system and method for parallel wind power converters

Abstract

The present invention discloses a power distribution and speed control system and method for parallel wind power converters. The system is connected to a power grid and a motor, and includes: at least two wind power converters, at least two wind power converters are connected in communication, the wind power converter includes a grid-side converter, a machine-side converter and a chopper, one end of the grid-side converter is connected to one end of the machine-side converter through two DC bus bars, the other end of the grid-side converter is connected to the power grid, the other end of the machine-side converter is connected to the motor, the chopper is connected across the two DC bus bars, one of the wind power converters is configured as a host, and the other wind power converter is configured as a slave. The present invention can ensure that all converters receive the same instructions synchronously by distinguishing between the host and the slave, and utilizing the real-time communication mechanism between the host and the slave, thereby realizing power distribution and speed control, ensuring good tracking effects of output current, power and speed, and improving the reliability and efficiency of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a power distribution and speed control system and method for a parallel wind power converter. Background Art

[0002] In wind power generation systems, wind power converters are key equipment that is responsible for converting and controlling wind energy into electrical energy through wind turbines. Early wind power converters, especially for low-power applications, usually adopted a single-machine operation mode, that is, a single converter could meet the power conversion requirements of the system. However, with the continuous advancement of wind power technology and the continuous growth of wind turbine capacity, the power processing capacity of a single converter has gradually shown limitations and cannot meet the application requirements of high-power wind turbines.

[0003] In order to meet this challenge, the industry has begun to explore new technical solutions, mainly including single converter parallel power module branches and whole machine parallel connection. Among them, the parallel power module branch method has become the preferred solution for most converter expansions because of its relatively simple structure and unified controller, which makes it easy to achieve power distribution. In this solution, by adding parallel power module branches, the power processing capacity of the entire converter system can be effectively improved. At the same time, since all branches share a set of controllers, it is relatively easy to achieve balanced power distribution between branches.

[0004] However, as the requirements for flexibility and reliability of wind power systems continue to increase, the whole machine parallel solution has gradually gained attention. The whole machine parallel solution refers to the parallel operation of multiple converters with independent controllers. These converters can work independently or under the coordinated control of the master and slave machines. This method not only improves the redundancy and reliability of the system, but also enables the system to flexibly adjust power output according to actual needs.

[0005] In the whole machine parallel scheme, it is generally required that each parallel converter has the same power capacity, so that when receiving external power instructions, the total power can be evenly distributed to each converter. At present, in the power generation mode, the parallel converters usually receive the same external power instructions independently and realize the power distribution through the internal control algorithm. However, although this control strategy is simple and effective, it may not be able to achieve good power distribution and speed control when facing complex and changeable actual working conditions.

[0006] In addition, in electric mode, that is, when the wind power converter is used to drive the motor, the current parallel converter control strategy still has certain deficiencies. In particular, in application scenarios where precise control of the motor speed is required, due to the lack of an effective parallel converter speed control method, a single converter is usually used to achieve drag operation, which limits the overall performance and flexibility of the system. Summary of the invention

[0007] The purpose of the present invention is to provide a power distribution and speed control system and method for parallel wind power converters, aiming to solve the problems that the existing whole machine parallel scheme cannot achieve better power distribution and speed control when facing complex and changeable actual working conditions.

[0008] An embodiment of the present invention provides a power distribution and speed control system for a parallel wind power converter, which is connected to a power grid and a motor, and includes: at least two wind power converters, at least two wind power converters are communicatively connected to each other, the wind power converter includes a grid-side converter, a machine-side converter and a chopper, one end of the grid-side converter is connected to one end of the machine-side converter through two DC bus bars, the other end of the grid-side converter is connected to the power grid, the other end of the machine-side converter is connected to the motor, and the chopper is connected across the two DC bus bars, one of the wind power converters is configured as a host, and the other wind power converter is configured as a slave.

[0009] The embodiment of the present invention further provides a method for power distribution and speed control of a parallel wind power converter, which is applied to the power distribution and speed control system of the parallel wind power converter, and includes:

[0010] When the power distribution and speed control systems of the parallel wind turbine converters are configured to operate independently, the master and slaves receive external commands respectively;

[0011] When the power distribution and speed control systems of the parallel wind power converters are configured to operate in a master-slave collaborative manner, the master receives external commands and sends corresponding commands to the slaves.

[0012] Furthermore, the external instructions include: one or more of: grid-side converter pre-charging instructions, uncontrolled rectification instructions, grid-side converter modulation instructions, machine-side converter synchronization instructions, machine-side converter grid-connected operation instructions, converter torque instructions, active power instructions, reactive power instructions and converter speed setting instructions.

[0013] Furthermore, it also includes:

[0014] When both the master and the slave are in grid-connected operation, the master configures the active power it needs to output according to the received active power command, calculates the remaining active power, and sends the remaining active power command to the slave according to the remaining active power;

[0015] The slave receives the remaining active power command and executes it.

[0016] Furthermore, it also includes:

[0017] When the grid-side converters of the master and slave are both in the grid-connected modulation state, the master configures the reactive power that it needs to output according to the received reactive power command, calculates the remaining reactive power, and sends the remaining reactive power command to the slave according to the remaining reactive power;

[0018] The slave receives the remaining reactive power command and executes it.

[0019] Furthermore, it also includes:

[0020] When the wind power converter is in speed control mode to drive the motor, the host is configured in speed control mode, using a speed outer loop, and the host tracks the speed setting and outputs the torque required to maintain the speed;

[0021] The slave is configured in torque control mode, using a torque outer loop or an active power outer loop, and the slave tracks the torque setting and provides the remaining torque in addition to the torque provided by the master;

[0022] When the slave outputs excess torque, the master automatically adjusts its own torque according to the total output torque to maintain the total output torque unchanged.

[0023] Furthermore, it also includes:

[0024] When the wind power converter is in speed control mode and drives the motor to run, both the master and slave are configured in speed control mode;

[0025] The slave receives the host's instructions in real time and uses a speed outer loop;

[0026] The master receives and tracks the speed setting, generates the current setting through the speed regulator, and transmits the speed setting instruction and the current setting instruction to the slave according to the current setting and the speed setting;

[0027] The slave receives the speed setting instruction and the current setting instruction and ensures that the speed setting instruction and the current setting instruction are consistent, wherein the speed target and the torque target of the master and the slave are the same.

[0028] Furthermore, the speed outer loop includes:

[0029] The deviation of the speed setting is adjusted by proportional integral (PI) to obtain the q-axis current setting;

[0030] The given deviation of the q-axis current is adjusted through PI to obtain the wave voltage;

[0031] The wave voltage is processed successively through the control delay and the control object filter inductance to obtain the actual current value;

[0032] The actual current value is converted into the actual speed value of the motor via the control object.

[0033] Further, the torque outer ring includes:

[0034] The deviation between the torque setting and the torque feedback is passed through the PI regulator to obtain the current setting;

[0035] The current setting and current feedback are adjusted through PI to obtain the wave voltage;

[0036] The wave voltage is processed successively through the control delay and the control object filter inductance to obtain the actual current value;

[0037] The actual current value is converted into the actual output torque by the control object.

[0038] Furthermore, the active power outer loop is used including:

[0039] The deviation between the active power setting and the active power feedback is passed through the PI regulator to obtain the current setting;

[0040] The current setting and current feedback are adjusted through PI to obtain the wave voltage;

[0041] The wave voltage is processed successively through the control delay and the control object filter inductance to obtain the actual current value;

[0042] The actual current value is converted into actual output active power through the control object.

[0043] The present invention discloses a power distribution and speed control system and method for parallel wind power converters. The system is connected to a power grid and a motor, and includes: at least two wind power converters, at least two wind power converters are connected in communication, the wind power converter includes a grid-side converter, a machine-side converter and a chopper, one end of the grid-side converter is connected to one end of the machine-side converter through two DC bus bars, the other end of the grid-side converter is connected to the power grid, the other end of the machine-side converter is connected to the motor, the chopper is connected across the two DC bus bars, one wind power converter is configured as a host, and the other wind power converter is configured as a slave. The present invention can ensure that all wind power converters receive the same instructions synchronously by distinguishing between the host and the slave, and using the real-time communication mechanism between the host and the slave, so as to realize power distribution and speed control, and realize the coordinated operation of the parallel whole machine using multiple controllers, and as a wind power converter, it outputs power or controls the motor speed, and can ensure good tracking effects such as output current, power and speed, thereby improving the reliability and efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0045] Figure 1 It is a schematic diagram of the structure of the power distribution and speed control system of the parallel wind power converter;

[0046] Figure 2 A flow chart of a power distribution and speed control method for parallel wind power converters;

[0047] Figure 3 It is a flow chart of the function of independent operation of a single unit of parallel converter;

[0048] Figure 4 It is a flow chart of the active power sharing function in the master-slave operation mode of the parallel converter;

[0049] Figure 5 It is a flow chart of the reactive power sharing function in the master-slave operation mode of the parallel converter;

[0050] Figure 6 A schematic diagram of a sub-process of a power distribution and speed control method for parallel wind power converters;

[0051] Figure 7 A schematic diagram of another sub-flow of the power distribution and speed control method for parallel wind power converters;

[0052] Figure 8 is the control loop diagram of the converter speed control mode;

[0053] Fig. 9 This is the control loop diagram of the converter torque control mode. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0056] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0057] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0058] See also Figure 1 The present embodiment provides a power distribution and speed control system of a parallel wind power converter, which is connected to a power grid and a motor, and includes: at least two wind power converters, at least two wind power converters are communicatively connected to each other, the wind power converter includes a grid-side converter, a machine-side converter and a chopper, one end of the grid-side converter is connected to one end of the machine-side converter through two DC bus bars, the other end of the grid-side converter is connected to the power grid, the other end of the machine-side converter is connected to the motor, the chopper is connected across the two DC bus bars, one of the wind power converters is configured as a host, and the other wind power converter is configured as a slave.

[0059] This embodiment distinguishes between the host and the slave and utilizes the real-time communication mechanism between the host and the slave to ensure that all wind power converters receive the same instructions synchronously, realize power distribution and speed control, and simultaneously realize the coordinated operation of the whole machine in parallel using multiple controllers. As a wind power converter outputs power to the outside or controls the motor speed, it can ensure good tracking effects such as output current, power and speed, thereby improving the reliability and efficiency of the system.

[0060] In some embodiments, the motor is a generator in torque mode and a motor in speed mode. The motor has at least two windings, each winding is connected to a wind power converter.

[0061] The motor includes but is not limited to a permanent magnet synchronous motor (PMSM), which is characterized by having two or more windings. These windings can be Y-connected or Δ-connected, depending on the design requirements. Each winding is connected to its own wind power converter via a cable, and the wind power converter is further connected to the grid or energy storage device.

[0062] Torque mode: When the motor is driven by external mechanical energy, such as a wind turbine, it enters torque mode and starts generating electricity. At this time, the wind turbine converter rectifies the AC power generated by the motor into DC power, which can then be inverted into AC power suitable for grid connection as needed.

[0063] Speed ​​mode: Conversely, when electrical energy is input to the motor, such as electricity from the grid, the motor will operate as a motor in speed mode. At this time, the wind turbine converter converts the received DC power into appropriate AC power to excite the motor windings, thereby generating a rotating magnetic field to turn the rotor.

[0064] The motor contains at least two windings, each connected to a wind turbine converter. This design allows the motor to control current and voltage more flexibly, thereby optimizing its performance. The design of multiple windings also helps to disperse current and heat, reduce the load of a single winding, and thus improve the efficiency and reliability of the motor. At the same time, this design also increases the redundancy of the motor. Even if one winding fails, the other winding can still maintain the basic operation of the motor.

[0065] In some embodiments, the master and slave have exactly the same control system, and any wind turbine converter can serve as the master. The slaves can be configured to run simultaneously following the master's instructions, or they can be configured to run independently.

[0066] Since any converter can be used as the host, when the current host fails or needs maintenance, another converter can be quickly configured as the host to ensure continuous operation of the system. This redundant design improves system reliability and reduces downtime caused by single point failures.

[0067] See also Figure 2 This embodiment further provides a method for power distribution and speed control of a parallel wind power converter, which is applied to the power distribution and speed control system of the parallel wind power converter in the above embodiment, and includes:

[0068] S101: When the power distribution and speed control system of the parallel wind power converter is configured to operate independently, the master and the slave each receive an external instruction;

[0069] S102: When the power distribution and speed control system of the parallel wind power converter is configured to operate in a master-slave cooperative manner, the master receives an external instruction and sends a corresponding instruction to the slave.

[0070] The method supports two modes of independent operation and master-slave cooperative operation of the power distribution and speed control system of parallel wind turbine converters. In the independent operation mode, the master and slave each receive external instructions and can complete the control tasks independently, which improves the flexibility and scalability of the system. In the master-slave cooperative operation mode, the master acts as the control center, responsible for receiving external instructions and issuing corresponding instructions to the slave. This design enables the system to handle complex control tasks more efficiently while maintaining high stability and reliability.

[0071] In this embodiment, the external instructions include: one or more of: grid-side converter pre-charging instructions, uncontrolled rectification instructions, grid-side converter modulation instructions, machine-side converter synchronization instructions, machine-side converter grid-connected operation instructions, converter torque instructions, active power instructions, reactive power instructions and converter speed setting instructions.

[0072] Among them, the pre-charging instruction or other instructions can come from the main control signal or the converter monitoring background signal. After the host receives the pre-charging instruction or other instructions, if it is the master-slave cooperative operation mode, the instruction is transmitted to the slave at the same time. The host and the slave close the grid-side pre-charging contactor according to the grid-side converter pre-charging instruction, and charge the converter bus capacitor through the grid voltage and the pre-charging resistor. Close the grid-side main circuit breaker according to the uncontrolled rectification instruction. Start the pulse width modulation (PWM) wave control power semiconductor device according to the grid-side converter modulation instruction. Adjust the wave voltage to make it close to the motor voltage and close the machine-side contactor according to the machine-side converter synchronization instruction. Realize torque or power closed-loop control according to the machine-side converter grid-connected operation instruction.

[0073] In some embodiments, the parallel full-power wind turbine converter adopts Figure 1 In the topology shown, the independent operation function of the converter is as follows: the power distribution and speed control systems of the parallel wind power converters are configured to operate independently, the codes and parameters used by different wind power converters are consistent, each wind power converter can receive external instructions to operate, and the wind power converter is in the grid-connected operation state of the torque control mode.

[0074] See also Figure 3 ,Specifically, the power distribution and speed control system of the parallel ,wind power converters are set to an independent single machine mode, and the ,wind power converters do not receive each other’s information;

[0075] Each wind power converter has an independent command transmission channel with the main control and other external controllers. When the main control sends a start command, each wind power converter operates independently.

[0076] When all wind power converters are started and connected to the grid, the master controller sends the active power and reactive power to be output by each wind power converter to the corresponding wind power converter, and each wind power converter executes the corresponding instructions to realize power distribution.

[0077] This method ensures that the operations of different wind power converters do not interfere with each other, and achieves efficient active and reactive power distribution. At the same time, each wind power converter has established an independent command transmission channel with the main control and other external controllers to ensure accurate transmission and timely response of commands.

[0078] In some embodiments, when the power distribution and speed control system of the parallel wind power converter is configured to operate in master-slave coordination, the other configuration parameters are the same, only the active power instruction sent by the master control is received by the master, and the slave receives the remaining active power instruction of the master, and the wind power converter is in the grid-connected operation state of the torque control mode. Specifically, it also includes:

[0079] When both the master and the slave are in grid-connected operation (i.e., both the grid-side converter and the machine-side converter are in modulation operation, transmitting the power output by the motor to the grid), the master configures the active power that it needs to output according to the received active power instruction, calculates the remaining active power, and sends the remaining active power instruction to the slave according to the remaining active power;

[0080] The slave receives the remaining active power command and executes it.

[0081] See also Figure 4 ,More specifically, the power distribution and speed control system of the ,parallel wind power converters are configured to operate in a coordinated ,master-slave mode, and the master and the slave are connected ,through real-time signal lines;

[0082] When the master control sends an external command to the host, the host sends the same startup command to the slave, and the slave receives it in real time. The host and the slave start up and connect to the grid at the same time.

[0083] Then, when the master control sends the total active power command to the host, the host configures the active power it needs to output according to the received active power command, calculates the remaining active power, and sends the remaining active power command to the slave according to the remaining active power. The slave receives the remaining active power command and executes it.

[0084] The host can intelligently configure the active power it needs to output according to the total active power command received, and accurately calculate the remaining active power. This precise power allocation strategy ensures that each wind power converter (including the host and slave) can operate in an optimal manner, thereby improving the energy efficiency of the entire wind farm. At the same time, the host can dynamically adjust its own output power according to the total active power command and its own operating status, and adjust the output power of the slave accordingly. This flexible power regulation capability enables the system to adapt to different wind conditions and grid requirements, improving the adaptability and flexibility of the system.

[0085] In some embodiments, when the power distribution and speed control system of the parallel wind power converter is configured to operate in master-slave coordination, the other configuration parameters are the same, only the host receives the reactive power command sent by the master control, and the slave receives the remaining reactive power command of the host, and the grid-side converters are in the grid-connected modulation state. Specifically, it also includes:

[0086] When the grid-side converters of the master and slave are both in the grid-connected modulation state (i.e., the grid-side circuit breaker is closed and the grid-side converter is in the modulation state, and the machine-side converter can be in the modulation operation or not), the master configures the reactive power that it needs to output according to the received reactive power instruction, calculates the remaining reactive power, and sends the remaining reactive power instruction to the slave according to the remaining reactive power;

[0087] The slave receives the remaining reactive power command and executes it.

[0088] See also Figure 5 ,More specifically, the power distribution and speed control system of the ,parallel wind power converters are configured to operate in a coordinated ,master-slave mode, and the master and the slave are connected ,through real-time signal lines;

[0089] Then the master control sends an external command to the host, and the host sends the same startup command to the slave. The slave receives it in real time, and the host and the slave start up and connect to the grid at the same time.

[0090] Then the master control sends the total reactive power command to the host. The host configures the reactive power it needs to output based on the received reactive power command, calculates the remaining reactive power, and sends the remaining reactive power command to the slave based on the remaining reactive power; the slave receives the remaining reactive power command and executes it.

[0091] The host is responsible for receiving and processing the total reactive power instructions from the main control system, accurately configuring the reactive power it needs to output according to system requirements, and calculating the remaining reactive power.

[0092] This configuration ensures the accuracy and efficiency of power distribution, avoiding the waste of reactive power and over-regulation of the system. In addition, the host and slave are connected through real-time signal lines to ensure the immediate transmission and response of instructions. At the same time, since the host is responsible for processing the total reactive power instructions and sending the remaining reactive power instructions to the slaves based on the calculation results, this centralized control method enhances the stability and reliability of the system.

[0093] In some embodiments, when the power distribution and speed control systems of the parallel wind turbine converters are configured to operate independently, the method further includes:

[0094] When the wind power converter is in speed control mode to drive the motor (i.e. both the grid-side converter and the generator-side converter are in modulation operation, transmitting the input grid power to the motor), the host is configured in speed control mode, using a speed outer loop, and the host tracks the speed setting, while outputting the torque required to maintain the speed;

[0095] The slave is configured in torque control mode, using a torque outer loop or an active power outer loop, and the slave tracks the torque setting and provides the remaining torque in addition to the torque provided by the master;

[0096] When the slave outputs excess torque, the master automatically adjusts its own torque according to the total output torque to maintain the total output torque unchanged.

[0097] The host is configured in speed control mode, which accurately tracks the speed setting through the speed outer loop and outputs the torque required to maintain the speed.

[0098] This configuration ensures that the motor can maintain a stable speed during the drag operation to meet specific operation requirements. The slave is configured in torque control mode or active power control mode, and automatically adjusts its output according to the torque or active power provided by the master to provide the remaining torque or active power. This collaborative working method ensures accurate control of the total output torque or active power.

[0099] Among them, the use of the speed outer loop includes: adjusting the deviation of the given speed through PI to obtain the q-axis current setting; then adjusting the deviation of the given q-axis current through PI to obtain the wave voltage; then the wave voltage is processed through the control delay and the control object filter inductance in turn to obtain the actual current value; and then the actual current value is converted into the actual speed value of the motor through the control object.

[0100] The use of the torque outer loop includes: passing the deviation between the torque setting and the torque feedback through the PI regulator to obtain the current setting; then passing the current setting and the current feedback through PI regulation to obtain the ripple voltage; then the ripple voltage is processed through the control delay and the control object filter inductance in turn to obtain the actual current value; and then the actual current value is converted into the actual output torque through the control object.

[0101] The use of the active power outer loop includes: passing the deviation between the active power setting and the active power feedback through the PI regulator to obtain the current setting; then passing the current setting and the current feedback through PI regulation to obtain the ripple voltage; then the ripple voltage is processed through the control delay and the control object filter inductance in turn to obtain the actual current value; and then the actual current value is converted into the actual output active power through the control object.

[0102] The design of the speed outer loop, torque outer loop and active power outer loop enables the control system to flexibly select control strategies according to different operating modes and requirements. This design improves the adaptability and flexibility of the control system, enabling it to adapt to various complex operating environments and conditions. At the same time, the PI regulator accurately controls the speed, torque and active power to ensure the stability and reliability of the system. This control method can quickly respond to changes in the system, suppress disturbances and fluctuations, and thus maintain stable operation of the system.

[0103] See also Figure 6,Specifically, (1) the wind power converter is connected to the motor, and the motor may be mechanically connected to the generator motor, or may not be connected to the generator motor;

[0104] (2) The power distribution and speed control systems of the parallel wind turbine converters are configured in independent operation mode, and the wind turbine converters do not receive information from each other;

[0105] (3) In this mode, the wind power converter uses its own control instructions, the master is configured in speed control mode, and the slave is configured in torque control mode;

[0106] (4) The host then obtains the real-time speed of the motor, and adjusts the deviation of the given speed through PI to obtain the given q-axis current. The deviation of the given current is adjusted through PI to obtain the wave voltage, and then the actual current value is obtained after the control delay and the control object filter inductance, and then converted to the actual speed value of the motor through the control object. While tracking the speed, the required torque of the generating side and the loss is output, as shown in the following example. Figure 8 As shown in the figure, ω ref is the motor speed given, ω Act is the motor speed feedback, K SpdP is the speed loop proportional coefficient, K SpdI is the speed loop integral coefficient, I qref is the Q-axis current given, I qact is the Q-axis current feedback, K CurrP is the current loop proportionality coefficient, K CurrI is the current loop integral coefficient, u pwm is the wave voltage, is the delay link, L is the machine-side filter inductance; Ts is the pure delay time; s is the complex frequency domain variable.

[0107] (5) Then the slave tracks the torque setting. The deviation between the torque setting and the torque feedback is obtained through the PI regulator to obtain the current loop setting. The current setting and feedback are adjusted by PI to obtain the wave voltage. After the control delay and the control object filter inductance, the actual current value is obtained, and then converted into the actual output torque through the control object. For details, see the control loop as shown in Fig. 9 As shown in the figure, T ref is the motor torque given, T Act is the motor torque feedback, K TorqueP is the torque loop proportional coefficient, K TorqueI is the torque loop integral coefficient, I qref is the Q-axis current given, I qact is the Q-axis current feedback, K CurrP is the current loop proportionality coefficient, K CurrI is the current loop integral coefficient, u pwm is the wave voltage, is the delay link, and L is the machine-side filter inductor.

[0108] It should be noted that the active power outer loop and the torque outer loop are the same type of variables. Active power is equal to torque multiplied by speed. Therefore, the active power closed-loop control loop is similar to the torque closed-loop control loop. It only requires replacing the torque reference with the active power reference and the torque feedback with the active power feedback.

[0109] (6) When the slave machine outputs a certain torque, the master machine automatically adjusts its own torque according to the total torque demand so that the total output torque remains unchanged, thereby achieving speed control and torque control.

[0110] In some embodiments, when the power distribution and speed control system of the parallel wind power converter is configured to operate in a master-slave cooperative manner, it also includes:

[0111] When the wind power converter is in speed control mode and drives the motor to run, both the master and slave are configured in speed control mode;

[0112] The slave receives the host's instructions in real time and uses a speed outer loop;

[0113] The master receives and tracks the speed setting, generates the current setting through the speed regulator, and transmits the speed setting instruction and the current setting instruction to the slave according to the current setting and the speed setting;

[0114] The slave receives the speed setting instruction and the current setting instruction and ensures that the speed setting instruction and the current setting instruction are consistent, wherein the speed target and the torque target of the master and the slave are the same.

[0115] See also Figure 7 ,Specifically, (1) the wind power converter is connected to the motor, and the motor may be mechanically connected to the generator motor, or may not be connected to the generator motor;

[0116] (2) The power distribution and speed control systems of the parallel wind turbine converters are configured in a master-slave cooperative operation mode, with the master and slave connected via real-time signal lines;

[0117] (3) In this mode, the wind turbine converter can use its own control instructions or the master control instructions. Both the master and slave are configured in speed control mode.

[0118] (4) The host and the slave independently obtain the real-time speed of the motor. Since it is the same motor, the speed feedback is the same. The host receives the speed setting, and the deviation of the speed setting is adjusted by PI to obtain the q-axis current setting. Then, the deviation of the q-axis current setting is adjusted by PI to obtain the wave voltage, and then the actual current value is obtained after the control delay and the control object filter inductance, and then converted to the actual speed value of the motor through the control object. While tracking the speed, the required torque of the generating side and the loss is output. The torque corresponding to the current speed of the motor is determined by the motor motion equation 1. The specific control loop is as follows Figure 8 As shown;

[0119]

[0120] Where, T e is the electromagnetic torque output by the motor, T l is the load torque, J is the motor’s moment of inertia, n p is the number of motor pole pairs, ω is the motor rotation angular frequency; t represents time.

[0121] (5) The slave receives the speed setting and machine-side operation instructions from the master in real time. It also tracks the speed setting through the speed regulator and current regulator in the previous step and outputs the required torque at the same time. The specific control loop is as follows: Figure 8 As shown;

[0122] (6) Since the given, feedback, and regulator parameters of the speed control loops of the master and slave are basically the same, the torques output by the parallel converters are also basically the same, thereby achieving speed control and torque sharing control;

[0123] (7) If the speed setting sent by the host to the slave is not real-time, the time difference of command transmission can be measured first, and the speed setting command received by the host can be delayed by the corresponding time difference, so as to achieve consistency between the speed setting and regulator output of the two.

[0124] When the wind power converter is in speed control mode to drive the motor, both the host and the slave are configured in speed control mode, ensuring the response speed and accuracy of the entire system. At the same time, the host and the slave independently obtain the real-time speed of the motor. Since it is the same motor, the speed feedback is the same, which ensures the accuracy of speed control. In addition, the host adjusts the deviation of the speed setting through the PI regulator to obtain the q-axis current setting, and then after a series of adjustments and conversions, the actual value of the motor speed is finally obtained. This adjustment method ensures the stability and accuracy of speed control.

[0125] In some embodiments, the host determines the instructions to be executed based on its own operating status, and the slave also determines whether to execute the received host instructions based on its own operating status. If the host or slave status does not meet the execution instructions, both will report a fault to the other and shut down.

[0126] When the status of the master or slave does not meet the execution instruction, both will report the other's fault and shut down. This fault detection mechanism can detect problems in the system in time and take corresponding measures to avoid further damage. This mechanism enhances the robustness of the system, enables the system to run stably in a complex and changing environment, and improves the reliability and availability of the system.

[0127] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0128] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive.

[0129] Inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "including a..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

Claims

1. A power distribution and speed control system for parallel wind power converters, connected to a power grid and a motor, characterized in that: include: At least two wind power converters are communicatively connected with each other, the wind power converters include a grid-side converter, a machine-side converter and a chopper, one end of the grid-side converter is connected to one end of the machine-side converter through two DC bus bars, the other end of the grid-side converter is connected to the grid, the other end of the machine-side converter is connected to the motor, and the chopper is connected across the two DC bus bars, wherein one of the wind power converters is configured as a host, and the other wind power converter is configured as a slave.

2. A method for power distribution and speed control of a parallel wind power converter, the method being applied to the power distribution and speed control system of the parallel wind power converter as claimed in claim 1, characterized in that: include: When the power distribution and speed control system of the parallel wind power converter is configured to operate independently, the master and the slave each receive an external instruction; When the power distribution and speed control system of the parallel wind power converter is configured to operate in a master-slave cooperative manner, the master receives external instructions and sends corresponding instructions to the slave.

3. The power distribution and speed control method of parallel wind power converters according to claim 2, characterized in that: The external instructions include: one or more of: grid-side converter pre-charging instructions, uncontrolled rectification instructions, grid-side converter modulation instructions, machine-side converter synchronization instructions, machine-side converter grid-connected operation instructions, converter torque instructions, active power instructions, reactive power instructions and converter speed setting instructions.

4. The power distribution and speed control method of parallel wind power converters according to claim 3, characterized in that: Also includes: When the host and the slave are both in a grid-connected operation state, the host configures the active power that needs to be output according to the received active power instruction, calculates the remaining active power, and sends the remaining active power instruction to the slave according to the remaining active power; The slave receives and executes the remaining active power instruction.

5. The power distribution and speed control method of parallel wind power converter according to claim 3 is characterized in that: Also includes: When the grid-side converters of the host and the slave are both in a grid-connected modulation state, the host configures the reactive power that needs to be output according to the received reactive power instruction, calculates the remaining reactive power, and sends the remaining reactive power instruction to the slave according to the remaining reactive power; The slave receives and executes the remaining reactive power instruction.

6. The power distribution and speed control method of parallel wind power converters according to claim 3, characterized in that: Also includes: When the wind power converter is in the speed control mode to drive the motor, the host is configured in the speed control mode, adopts the speed outer loop, and the host tracks the speed setting and outputs the torque required to maintain the speed; The slave is configured in a torque control mode, using a torque outer loop or an active power outer loop, and the slave tracks a given torque and provides a remaining torque in addition to the torque provided by the host; When the slave machine outputs the remaining torque, the host machine automatically adjusts its own torque according to the total output torque to maintain the total output torque unchanged.

7. The power distribution and speed control method of parallel wind power converters according to claim 3, characterized in that: Also includes: When the wind power converter is in the speed control mode to drive the motor to operate, the master and the slave are both configured in the speed control mode; The slave receives the instruction of the host in real time and adopts the speed outer loop; The host receives and tracks the speed setting, generates the current setting through the speed regulator, and transmits the speed setting instruction and the current setting instruction to the slave according to the current setting and the speed setting; The slave receives the speed setting instruction and the current setting instruction and ensures that the speed setting instruction and the current setting instruction are consistent, wherein the speed target and the torque target of the master and the slave are the same.

8. The method for power distribution and speed control of parallel wind power converters according to claim 6 or 7, characterized in that: The speed outer ring includes: The deviation of the given speed is adjusted through the proportional integral PI to obtain the given q-axis current; The given deviation of the q-axis current is adjusted through PI to obtain the wave voltage; The wave voltage is processed sequentially through the control delay and the control object filter inductance to obtain the actual value of the current; The actual current value is converted into an actual speed value of the electric motor by a control object.

9. The method for power distribution and speed control of parallel wind power converters according to claim 6, characterized in that: The torque outer ring includes: The deviation between the torque setting and the torque feedback is passed through the PI regulator to obtain the current setting; The current setting and current feedback are adjusted through PI to obtain the wave voltage; The wave voltage is processed sequentially through the control delay and the control object filter inductance to obtain the actual value of the current; The actual current value is converted into an actual output torque by a control object.

10. The method for power distribution and speed control of parallel wind power converters according to claim 6, characterized in that: The active power outer loop includes: The deviation between the active power setting and the active power feedback is passed through the PI regulator to obtain the current setting; The current setting and current feedback are adjusted through PI to obtain the wave voltage; The wave voltage is processed sequentially through the control delay and the control object filter inductance to obtain the actual value of the current; The actual current value is converted into actual output active power through the control object.

Images