Permanent magnet synchronous generator MPCC control method and system

Abstract

The invention discloses a permanent magnet synchronous generator MPCC control method and system. The method comprises the steps that output data of a permanent magnet synchronous generator are collected; establishing a system time domain equation, and preprocessing the system time domain equation according to the output data to obtain a system model prediction equation; correcting an error of an actual control system based on the system model prediction equation; and performing rolling optimization on the error corresponding to each voltage vector by using a value function based on a current error to obtain an optimal switching vector which minimizes the value function, and acting the optimal switching vector on a machine side rectifier to complete control on the permanent magnet synchronous generator. The method has better dynamic response characteristics and anti-interference performance.

Description

Technical Field

[0001] This invention relates to the field of synchronous control technology, and in particular to a permanent magnet synchronous generator (MPCC) control method and system. Background Technology

[0002] Model-Predicted Current Control (MPCC) is an advanced motor control method that predicts the difference between the current and a reference current, using this difference as input to a cost function to obtain the optimal voltage vector output with the minimum error. However, MPCC is highly sensitive to parameter variations; performance degrades significantly if the model parameters do not match the actual machine parameters. Since MPCC requires accurate motor model parameters to predict future states, parameter mismatch has a significant impact on control performance. To address this issue, Model-Free Predictive Current Control (MFPCC) based on a hyperlocal model can be employed. This model uses only the system's inputs and outputs, without considering any motor parameters, thus improving the robustness of the control system. In wind power systems, PMSG needs to achieve maximum power point tracking (MPPT) and requires high control precision to ensure power generation efficiency. Simultaneously, the system needs good dynamic response characteristics to cope with changes in external conditions such as wind speed variations. Grid-connected current harmonic distortion (THD) needs to be controlled at a low level to ensure system stability and power quality. In scenarios considering the impact of transmission delay, improved MPCC strategies, such as two-step delay-compensated MPCC, are needed to reduce the impact of transmission delay. In scenarios requiring reduced system switching losses and improved system efficiency, switching frequency limiting strategies need to be introduced to minimize switching losses during motor control. Since motor parameters are crucial to MPCC control performance, accurate acquisition of these parameters is essential, which typically involves a complex parameter identification process. Summary of the Invention

[0003] The present invention aims to at least partially solve one of the technical problems in the related art.

[0004] To address this, the present invention proposes a permanent magnet synchronous generator (MPCC) control method, which exhibits better dynamic response characteristics and anti-interference capabilities under conditions of repeated generator start-stop and torque and speed changes.

[0005] Another objective of this invention is to provide a permanent magnet synchronous generator (MPCC) control system.

[0006] To achieve the above objectives, the present invention provides a permanent magnet synchronous generator (MPCC) control method, comprising:

[0007] Collect output data from a permanent magnet synchronous generator;

[0008] Establish the system time-domain equations, and preprocess the system time-domain equations based on the output data to obtain the system model prediction equations;

[0009] The error of the actual control system is corrected based on the prediction equation of the system model.

[0010] The optimal switching vector that minimizes the value function is obtained by using a value function based on current error to perform rolling optimization on the error corresponding to each voltage vector, and the optimal switching vector is applied to the machine-side rectifier to complete the control of the permanent magnet synchronous generator.

[0011] The permanent magnet synchronous generator (MPCC) control method of this invention may also have the following additional technical features:

[0012] In one embodiment of the present invention, the acquisition of output data from a permanent magnet synchronous generator includes:

[0013] The output voltage signal and three-phase stator current signal of the permanent magnet synchronous generator are obtained through voltage and current transformers.

[0014] The generator speed and rotor angular velocity are obtained through speed and position sensors, and the accumulator pressure is obtained through pressure sensors.

[0015] In one embodiment of the present invention, the system time-domain equations are preprocessed based on the output data to obtain the system model prediction equations, including:

[0016] Based on the pre-defined PMSG stator voltage equations, the current prediction model for the next time step (k+1) is obtained by discretization using the forward Euler equations:

[0017]

[0018] In the formula, Ts is the system control cycle.

[0019] In one embodiment of the present invention, the error correction of the actual control system based on the system model prediction equation includes:

[0020] Based on the time delay caused by sampling and calculation in the actual control system, and based on the measured generator output current d, q-axis components id(k), iq(k) and the applied generator-side voltage d, q-axis components ud(k), uq(k) at the current moment, using Let represent the one-beat delay compensation current for the d-axis and q-axis respectively. Based on equation (1), the calculation formula for the one-beat delay compensation current is derived as follows:

[0021]

[0022] The measured currents id(k) and iq(k) in equation (1) are compensated by a one-beat delay using equation (2). Substituting (k+1) yields the updated current prediction equation:

[0023]

[0024] In the formula, ud(k+1) and uq(k+1) represent the basic voltage vectors to be applied at the next time step.

[0025] In one embodiment of the present invention, the method further includes:

[0026] Based on the system control objective, a cost function is designed for rolling optimization, and the vector that minimizes the cost function is selected as the optimal voltage vector in the space voltage vector. In the next cycle, the switching signal corresponding to the optimal voltage vector is applied to the rectifier to drive the permanent magnet synchronous generator to rotate and complete the corresponding power generation and rectification control.

[0027] The cost function based on current error is selected, and its expression is as follows:

[0028] g = (i d (k)-i d (k+2)) 2 +(i q (k)-i q (k+2)) 2 (4).

[0029] To achieve the above objectives, another aspect of the present invention provides a permanent magnet synchronous generator (MPCC) control system, comprising:

[0030] The motor data acquisition module is used to acquire the output data of the permanent magnet synchronous generator;

[0031] The time-domain equation processing module is used to establish the system time-domain equation and preprocess the system time-domain equation based on the output data to obtain the system model prediction equation.

[0032] An error correction module is used to correct the errors of the actual control system based on the prediction equations of the system model.

[0033] The motor control module is used to perform rolling optimization on the error corresponding to each voltage vector using a value function based on current error to obtain the optimal switching vector that minimizes the value function, and then apply the optimal switching vector to the machine-side rectifier to complete the control of the permanent magnet synchronous generator.

[0034] The permanent magnet synchronous generator MPCC control method and system of the present invention exhibit better dynamic response characteristics and anti-interference ability under torque and speed change conditions such as repeated start-stop of the generator, which can effectively improve the adaptability of wave energy power generation unit under various complex working conditions.

[0035] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0037] Figure 1 This is a flowchart of the MPCC control method for a permanent magnet synchronous generator according to an embodiment of the present invention;

[0038] Figure 2 This is a control logic diagram for one-time delay compensation MPCC according to an embodiment of the present invention;

[0039] Figure 3 This is a basic spatial voltage vector distribution diagram according to an embodiment of the present invention;

[0040] Figure 4 This is a structural diagram of the MPCC control system for a permanent magnet synchronous generator according to an embodiment of the present invention. Detailed Implementation

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0043] The following describes, with reference to the accompanying drawings, a permanent magnet synchronous generator (MPCC) control method and system according to an embodiment of the present invention.

[0044] Figure 1 This is a flowchart of the MPCC control method for a permanent magnet synchronous generator according to an embodiment of the present invention, as follows: Figure 1 As shown, the method includes:

[0045] S1, collects the output data of the permanent magnet synchronous generator;

[0046] S2, Establish the system time-domain equation, and preprocess the system time-domain equation according to the output data to obtain the system model prediction equation;

[0047] S3, based on the system model prediction equations, corrects the errors of the actual control system;

[0048] S4. The value function based on current error is used to perform rolling optimization on the error corresponding to each voltage vector to obtain the optimal switching vector that minimizes the value function, and the optimal switching vector is applied to the machine-side rectifier to complete the control of the permanent magnet synchronous generator.

[0049] Specifically, such as Figure 2 As shown, this invention acquires the output data of the permanent magnet synchronous generator through measuring devices such as speed sensors, position sensors, and voltage and current transformers; it obtains the system model prediction equation by simultaneously establishing the system time-domain equations based on the system structure and discretizing the time-domain equations; it corrects the errors caused by sampling and calculation delays in the actual process by using the delay compensation method; it uses the value function based on the current error to perform rolling optimization on the errors corresponding to each voltage vector to obtain the optimal switching vector that minimizes the value function, and applies this switching vector to the generator-side rectifier to finally complete the control of the permanent magnet synchronous generator.

[0050] Furthermore, the model input data sampling mainly obtains the output voltage signal of the permanent magnet synchronous generator and the three-phase stator current signal through voltage and current transformers; the generator speed and rotor angular velocity are obtained through speed and position sensors; and the accumulator pressure is obtained through pressure sensors.

[0051] Furthermore, based on the PMSG stator voltage equation, the current prediction model for the next time step (k+1) can be obtained by discretizing it using the forward Euler equation:

[0052]

[0053] In the formula, Ts is the system control cycle.

[0054] Furthermore, considering the delay caused by sampling and calculation in the actual control system, a one-beat delay is used to compensate for the predicted current in order to reduce system error. Based on the measured generator output current d, q-axis components id(k), iq(k) and the applied generator-side voltage d, q-axis components ud(k), uq(k) at the current moment, a time delay is used to... Let represent the one-beat delay compensation current for the d-axis and q-axis respectively. Based on equation (1), the calculation formula for the one-beat delay compensation current is derived as follows:

[0055]

[0056] The measured currents id(k) and iq(k) in equation (1) are compensated by a one-beat delay using equation (2). Substituting (k+1) yields the updated current prediction equation:

[0057]

[0058] In the formula, ud(k+1) and uq(k+1) represent the basic voltage vectors to be applied at the next time step.

[0059] Furthermore, for a three-phase two-level voltage-type rectifier, the switching process of the rectifier mathematical model is modeled and analyzed using switching functions (Sa, Sb, Sc), resulting in the basic voltage space vector table shown in Table 1.

[0060] Table 1

[0061] vector <![CDATA[u0]]> <![CDATA[u1]]> <![CDATA[u2]]> <![CDATA[u3]]> <![CDATA[u4]]> <![CDATA[u5]]> <![CDATA[u6]]> <![CDATA[u7]]> <![CDATA[S a ]]> 0 0 0 0 1 1 1 1 <![CDATA[S b ]]> 0 0 1 1 0 0 1 1 <![CDATA[S c ]]> 0 1 0 1 0 1 0 1

[0062] The corresponding basic voltage space vector distribution is as follows: Figure 3 As shown.

[0063] Based on the system control objective, a cost function is designed for rolling optimization, and the vector that minimizes the cost function among the above 8 spatial voltage vectors (u0~u7) is selected as the optimal voltage vector. In the next cycle, the switching signal corresponding to the optimal voltage vector is applied to the rectifier to drive the permanent magnet synchronous generator to rotate and complete the corresponding power generation and rectification control.

[0064] This invention selects a cost function based on current error, the expression of which is as follows:

[0065] g = (i d (k)-i d (k+2)) 2 +(i q (k)-i q (k+2)) 2 (4)

[0066] The permanent magnet synchronous generator (MPCC) control method according to embodiments of the present invention has better dynamic response characteristics and anti-interference ability. It can respond quickly in speed control. The grid-connected inverter voltage-oriented vector control strategy adopted can realize the voltage regulation control of the DC bus and the unity power factor operation of the system, which is more suitable for wave energy power generation, where generator sets need to be repeatedly started and stopped.

[0067] To achieve the above embodiments, such as Figure 4 As shown, this embodiment also provides a permanent magnet synchronous generator (MPCC) control system 10, including:

[0068] The motor data acquisition module 100 is used to acquire the output data of the permanent magnet synchronous generator.

[0069] The time-domain equation processing module 200 is used to establish the system time-domain equation and preprocess the system time-domain equation according to the output data to obtain the system model prediction equation.

[0070] Error correction module 300 is used to correct the error of the actual control system based on the prediction equation of the system model;

[0071] The motor control module 400 is used to perform rolling optimization on the error corresponding to each voltage vector using a value function based on current error to obtain the optimal switching vector that minimizes the value function, and then apply the optimal switching vector to the machine-side rectifier to complete the control of the permanent magnet synchronous generator.

[0072] In one embodiment of the present invention, the motor data acquisition module 100 is further configured to:

[0073] The output voltage signal and three-phase stator current signal of the permanent magnet synchronous generator are obtained through voltage and current transformers.

[0074] The generator speed and rotor angular velocity are obtained through speed and position sensors, and the accumulator pressure is obtained through pressure sensors.

[0075] In one embodiment of the present invention, the time-domain equation processing module 200 is further configured to:

[0076] Based on the pre-defined PMSG stator voltage equations, the current prediction model for the next time step (k+1) is obtained by discretization using the forward Euler equations:

[0077]

[0078] In the formula, Ts is the system control cycle.

[0079] In one embodiment of the present invention, the error correction module 300 is further configured to:

[0080] Based on the time delay caused by sampling and calculation in the actual control system, and based on the measured generator output current d, q-axis components id(k), iq(k) and the applied generator-side voltage d, q-axis components ud(k), uq(k) at the current moment, using Let represent the one-beat delay compensation current for the d-axis and q-axis respectively. Based on equation (1), the calculation formula for the one-beat delay compensation current is derived as follows:

[0081]

[0082] The measured currents id(k) and iq(k) in equation (1) are compensated by a one-beat delay using equation (2). By making substitutions, we obtain the updated current prediction equation expression:

[0083]

[0084] In the formula, ud(k+1) and uq(k+1) represent the basic voltage vectors to be applied at the next time step.

[0085] In one embodiment of the present invention, the motor control module 400 is further configured to:

[0086] Based on the system control objective, a cost function is designed for rolling optimization, and the vector that minimizes the cost function is selected as the optimal voltage vector in the space voltage vector. In the next cycle, the switching signal corresponding to the optimal voltage vector is applied to the rectifier to drive the permanent magnet synchronous generator to rotate and complete the corresponding power generation and rectification control.

[0087] The cost function based on current error is selected, and its expression is as follows:

[0088] g = (i d (k)-i d (k+2)) 2 +(i q (k)-i q (k+2)) 2 (4).

[0089] The permanent magnet synchronous generator (MPCC) control system according to embodiments of the present invention has superior dynamic response characteristics and anti-interference capabilities. It can respond quickly in speed control, and the grid-connected inverter voltage-oriented vector control strategy adopted can realize the voltage regulation control of the DC bus and the unity power factor operation of the system, making it more suitable for applications such as wave energy power generation where generator sets need to be repeatedly started and stopped.

[0090] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0091] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

Claims

1. A permanent magnet synchronous generator (MPCC) control method, characterized in that, include: Collect output data from a permanent magnet synchronous generator; Establish the system time-domain equations, and preprocess the system time-domain equations based on the output data to obtain the system model prediction equations; The error of the actual control system is corrected based on the prediction equation of the system model. The optimal switching vector that minimizes the value function is obtained by using a value function based on current error to perform rolling optimization on the error corresponding to each voltage vector, and the optimal switching vector is applied to the machine-side rectifier to complete the control of the permanent magnet synchronous generator.

2. The method according to claim 1, characterized in that, Collect the output data of the permanent magnet synchronous generator, including: The output voltage signal and three-phase stator current signal of the permanent magnet synchronous generator are obtained through voltage and current transformers. The generator speed and rotor angular velocity are obtained through speed and position sensors, and the accumulator pressure is obtained through pressure sensors.

3. The method according to claim 1, characterized in that, The system time-domain equations are preprocessed based on the output data to obtain the system model prediction equations, including: Based on the pre-defined PMSG stator voltage equations, the current prediction model for the next time step (k+1) is obtained by discretization using the forward Euler equations: In the formula, Ts is the system control cycle.

4. The method according to claim 3, characterized in that, The error correction of the actual control system based on the prediction equations of the system model includes: Based on the time delay caused by sampling and calculation in the actual control system, and based on the measured generator output current d, q-axis components id(k), iq(k) and the applied generator-side voltage d, q-axis components ud(k), uq(k) at the current moment, using Let represent the one-beat delay compensation current for the d-axis and q-axis respectively. Based on equation (1), the calculation formula for the one-beat delay compensation current is derived as follows: The measured currents id(k) and iq(k) in equation (1) are compensated by a one-beat delay using equation (2). By making substitutions, we obtain the updated current prediction equation expression: In the formula, ud(k+1) and uq(k+1) represent the basic voltage vectors to be applied at the next time step.

5. The method according to claim 1, characterized in that, The method further includes: Based on the system control objective, a cost function is designed for rolling optimization, and the vector that minimizes the cost function is selected as the optimal voltage vector in the space voltage vector. In the next cycle, the switching signal corresponding to the optimal voltage vector is applied to the rectifier to drive the permanent magnet synchronous generator to rotate and complete the corresponding power generation and rectification control. The cost function based on current error is selected, and its expression is as follows: g=(id(k)-id(k+2))2+(iq(k)-iq(k+2))2(4).

6. A permanent magnet synchronous generator (MPCC) control system, characterized in that, include: The motor data acquisition module is used to acquire the output data of the permanent magnet synchronous generator; The time-domain equation processing module is used to establish the system time-domain equation and preprocess the system time-domain equation based on the output data to obtain the system model prediction equation. An error correction module is used to correct the errors of the actual control system based on the prediction equations of the system model. The motor control module is used to perform rolling optimization on the error corresponding to each voltage vector using a value function based on current error to obtain the optimal switching vector that minimizes the value function, and then apply the optimal switching vector to the machine-side rectifier to complete the control of the permanent magnet synchronous generator.

7. The system according to claim 6, characterized in that, The motor data acquisition module is also used for: The output voltage signal and three-phase stator current signal of the permanent magnet synchronous generator are obtained through voltage and current transformers. The generator speed and rotor angular velocity are obtained through speed and position sensors, and the accumulator pressure is obtained through pressure sensors.

8. The system according to claim 6, characterized in that, The time-domain equation processing module is also used for: Based on the pre-defined PMSG stator voltage equations, the current prediction model for the next time step (k+1) is obtained by discretization using the forward Euler equations: In the formula, Ts is the system control cycle.

9. The system according to claim 8, characterized in that, The error correction module is also used for: Based on the time delay caused by sampling and calculation in the actual control system, and based on the measured generator output current d, q-axis components id(k), iq(k) and the applied generator-side voltage d, q-axis components ud(k), uq(k) at the current moment, using Let represent the one-beat delay compensation current for the d-axis and q-axis respectively. Based on equation (1), the calculation formula for the one-beat delay compensation current is derived as follows: The measured currents id(k) and iq(k) in equation (1) are compensated by a one-beat delay using equation (2). By substituting (k+1), we obtain the updated current prediction equation expression: In the formula, ud(k+1) and uq(k+1) represent the basic voltage vectors to be applied at the next time step.

10. The system according to claim 6, characterized in that, The motor control module is also used for: Based on the system control objective, a cost function is designed for rolling optimization, and the vector that minimizes the cost function is selected as the optimal voltage vector in the space voltage vector. In the next cycle, the switching signal corresponding to the optimal voltage vector is applied to the rectifier to drive the permanent magnet synchronous generator to rotate and complete the corresponding power generation and rectification control. The cost function based on current error is selected, and its expression is as follows: g=(id(k)-id(k+2))2+(iq(k)-iq(k+2))2(4).

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