Power grid subsynchronous oscillation suppression method and system for 2MW doubly-fed converter

Abstract

The invention provides a power grid subsynchronous oscillation suppression method and system for a 2MW doubly-fed converter, and the method comprises the steps: obtaining the voltage of a power grid, and judging whether the subsynchronous oscillation occurs in the power grid or not based on the voltage of the power grid; when subsynchronous oscillation occurs in the power grid, acquiring a conventional vector corresponding to the subsynchronous oscillation, and extracting subsynchronous resonance current on a rotor current dq axis of a generator; determining a subsynchronous voltage required to be output by an additional damping controller according to the subsynchronous resonance current on the rotor current dq axis of the generator; and controlling an IGBT (Insulated Gate Bipolar Translator) of a 2MW doubly-fed converter accessed to a power grid according to the conventional vector corresponding to the subsynchronous oscillation and the subsynchronous voltage required to be output. According to the technical scheme, subsynchronous oscillation of the power grid can be effectively suppressed, and safe and stable operation of the power grid is guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of power grid oscillation suppression, and in particular to a power grid subsynchronous oscillation suppression method and system for a 2MW doubly-fed converter. Background Art

[0002] When the grid voltage has subsynchronous oscillation (SSR), if it is not controlled, the stator of the doubly fed generator will show low damping characteristics, and the stator-rotor electromechanical coupling will cause the generator output active power and reactive power to oscillate greatly, further aggravating the grid problem. Therefore, it is urgent to propose a solution that can effectively suppress the subsynchronous oscillation of the grid. Summary of the invention

[0003] The present application provides a method and system for suppressing subsynchronous oscillation of a power grid for a 2MW doubly-fed converter, so as to at least solve the technical problem that the prior art cannot effectively suppress subsynchronous oscillation of a power grid.

[0004] The first aspect of the present application provides a method for suppressing subsynchronous oscillation of a power grid for a 2MW doubly-fed converter, the method comprising:

[0005] Acquiring a grid voltage, and determining whether subsynchronous oscillation occurs in the grid based on the grid voltage;

[0006] When subsynchronous oscillation occurs in the power grid, a conventional vector corresponding to the subsynchronous oscillation is obtained, and a subsynchronous resonant current on a dq axis of a generator rotor current is extracted;

[0007] Determining the subsynchronous voltage required to be output by the additional damping controller according to the subsynchronous resonant current on the dq axis of the generator rotor current;

[0008] The IGBT of the 2MW double-fed converter connected to the power grid is controlled according to the conventional vector corresponding to the sub-synchronous oscillation and the required output sub-synchronous voltage.

[0009] Preferably, judging whether subsynchronous oscillation occurs in the power grid based on the power grid voltage includes:

[0010] Using a bandpass filter to perform real-time filtering on the grid voltage to obtain a low-frequency component of the grid voltage;

[0011] When the low-frequency component is greater than a preset first threshold, it is determined that subsynchronous oscillation occurs in the grid voltage.

[0012] Further, the obtaining of the normal vector corresponding to the sub-synchronous oscillation includes:

[0013] Performing a dq transformation on the three-phase stator voltage of the grid voltage to obtain a stator voltage value corresponding to the subsynchronous oscillation;

[0014] Determining a rotor regulating voltage corresponding to the subsynchronous oscillation based on a rotor current reference value and a rotor current measured value of the generator;

[0015] Wherein, the conventional vector includes: rotor regulation voltage and stator voltage value.

[0016] Further, the extracting of the subsynchronous resonant current on the dq axis of the generator rotor current includes:

[0017] A bandpass filter is used to extract the subsynchronous resonant current on the dq axis of the generator rotor current.

[0018] Further, the controlling the IGBT of the 2MW doubly-fed converter connected to the grid according to the conventional vector corresponding to the sub-synchronous oscillation and the required output sub-synchronous voltage includes:

[0019] Determine the sum of the required output sub-synchronous voltage and the conventional vector corresponding to the sub-synchronous oscillation, and output the sum of the required output sub-synchronous voltage and the conventional vector corresponding to the sub-synchronous oscillation to the SVPWM vector control to drive the IGBT of the 2MW doubly-fed converter connected to the power grid.

[0020] The second embodiment of the present application provides a power grid subsynchronous oscillation suppression system for a 2MW doubly-fed converter, comprising:

[0021] An acquisition module, used for acquiring a grid voltage, and judging whether a subsynchronous oscillation occurs in the grid based on the grid voltage;

[0022] An extraction module, used for obtaining a conventional vector corresponding to the subsynchronous oscillation when the power grid has a subsynchronous oscillation, and extracting a subsynchronous resonant current on a dq axis of a generator rotor current;

[0023] A determination module, used to determine the sub-synchronous voltage required to be output by the additional damping controller according to the sub-synchronous resonant current on the dq axis of the generator rotor current;

[0024] A control module is used to control the IGBT of a 2MW double-fed converter connected to the power grid according to the conventional vector corresponding to the sub-synchronous oscillation and the required output sub-synchronous voltage.

[0025] Preferably, the acquisition module is also used for:

[0026] Using a bandpass filter to perform real-time filtering on the grid voltage to obtain a low-frequency component of the grid voltage;

[0027] When the low-frequency component is greater than a preset first threshold, it is determined that subsynchronous oscillation occurs in the grid voltage.

[0028] Furthermore, the extraction module is also used for:

[0029] Performing a dq transformation on the three-phase stator voltage of the grid voltage to obtain a stator voltage value corresponding to the subsynchronous oscillation;

[0030] Determining a rotor regulating voltage corresponding to the subsynchronous oscillation based on a rotor current reference value and a rotor current measured value of the generator;

[0031] Wherein, the conventional vector includes: rotor regulation voltage and stator voltage value.

[0032] The third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method described in the first aspect is implemented.

[0033] A fourth aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in the first aspect of the present application.

[0034] The technical solution provided by the embodiments of the present application brings at least the following beneficial effects:

[0035] The present application proposes a method and system for suppressing subsynchronous oscillation of a power grid for a 2MW doubly-fed converter, the method comprising: obtaining the power grid voltage, and judging whether subsynchronous oscillation occurs in the power grid based on the power grid voltage; when subsynchronous oscillation occurs in the power grid, obtaining the conventional vector corresponding to the subsynchronous oscillation, and extracting the subsynchronous resonant current on the dq axis of the generator rotor current; determining the subsynchronous voltage required to be output by the additional damping controller according to the subsynchronous resonant current on the dq axis of the generator rotor current; and controlling the IGBT of the 2MW doubly-fed converter connected to the power grid according to the conventional vector corresponding to the subsynchronous oscillation and the required output subsynchronous voltage. The technical solution proposed in the present application can effectively suppress subsynchronous oscillation of the power grid and ensure the safe and stable operation of the power grid.

[0036] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0038] Figure 1 A flowchart of a method for suppressing subsynchronous oscillation of a power grid for a 2MW doubly-fed converter according to an embodiment of the present application;

[0039] Figure 2 A block diagram of a rotor-side current inner loop transfer function including an additional damping controller provided according to an embodiment of the present application;

[0040] Figure 3 A detailed flow chart of power grid subsynchronous oscillation suppression of a doubly-fed converter provided according to an embodiment of the present application;

[0041] Figure 4 The present invention is a structural diagram of a grid subsynchronous oscillation suppression system for a 2MW doubly-fed converter according to an embodiment of the present application. DETAILED DESCRIPTION

[0042] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0043] The present application proposes a method and system for suppressing subsynchronous oscillation of a power grid for a 2MW doubly-fed converter, the method comprising: obtaining the power grid voltage, and judging whether subsynchronous oscillation occurs in the power grid based on the power grid voltage; when subsynchronous oscillation occurs in the power grid, obtaining the conventional vector corresponding to the subsynchronous oscillation, and extracting the subsynchronous resonant current on the dq axis of the generator rotor current; determining the subsynchronous voltage required to be output by the additional damping controller according to the subsynchronous resonant current on the dq axis of the generator rotor current; and controlling the IGBT of the 2MW doubly-fed converter connected to the power grid according to the conventional vector corresponding to the subsynchronous oscillation and the required output subsynchronous voltage. The technical solution proposed in the present application can effectively suppress subsynchronous oscillation of the power grid and ensure the safe and stable operation of the power grid.

[0044] A method and system for suppressing subsynchronous oscillation of a power grid for a 2MW doubly-fed converter according to an embodiment of the present application will be described below with reference to the accompanying drawings.

[0045] Embodiment 1

[0046] Figure 1 Flow chart of a method for suppressing subsynchronous oscillation of a power grid for a 2MW doubly-fed converter according to an embodiment of the present application, as shown in FIG. Figure 1 As shown, the method includes:

[0047] Step 1: Obtain the grid voltage, and determine whether subsynchronous oscillation occurs in the grid based on the grid voltage.

[0048] In an embodiment of the present disclosure, judging whether subsynchronous oscillation occurs in the power grid based on the power grid voltage includes:

[0049] Using a bandpass filter to perform real-time filtering on the grid voltage to obtain a low-frequency component of the grid voltage;

[0050] When the low-frequency component is greater than a preset first threshold, it is determined that subsynchronous oscillation occurs in the grid voltage.

[0051] Step 2: When subsynchronous oscillation occurs in the power grid, a conventional vector corresponding to the subsynchronous oscillation is obtained, and the subsynchronous resonant current on the dq axis of the generator rotor current is extracted.

[0052] In the embodiment of the present disclosure, the obtaining of the normal vector corresponding to the sub-synchronous oscillation includes:

[0053] Performing a dq transformation on the three-phase stator voltage of the grid voltage to obtain a stator voltage value corresponding to the subsynchronous oscillation;

[0054] Determining a rotor regulating voltage corresponding to the subsynchronous oscillation based on a rotor current reference value and a rotor current measured value of the generator;

[0055] Wherein, the conventional vector includes: rotor regulation voltage u dqr and stator voltage u dqs .

[0056] In the embodiment of the present disclosure, extracting the subsynchronous resonant current on the dq axis of the generator rotor current includes:

[0057] A bandpass filter is used to extract the subsynchronous resonant current on the dq axis of the generator rotor current.

[0058] Step 3: Determine the subsynchronous voltage required to be output by the additional damping controller according to the subsynchronous resonant current on the dq axis of the generator rotor current.

[0059] It should be noted that if Figure 2 The figure shows the transfer function block diagram of the rotor side current inner loop with an additional damping controller. After the subsynchronous resonant current passes through the PI controller, the output voltage component Δu dqr , in the figure, ω s =ω 0 -ω r ,ω s is the slip angular frequency, ω r is the rotor angular frequency, ω 0 is the synchronization angular frequency, is the magnetic leakage coefficient, L m is the stator-rotor mutual inductance, L s is the stator inductance, L r is the rotor inductance, R r is the rotor resistance, proportional amplifier Kinv , BPF is a bandpass filter, and PD is a proportional differential controller.

[0060] Step 4: Control the IGBT of the 2MW doubly-fed converter connected to the grid according to the normal vector corresponding to the sub-synchronous oscillation and the required output sub-synchronous voltage.

[0061] In the embodiment of the present disclosure, step 4 specifically includes:

[0062] Determine the sum of the required output sub-synchronous voltage and the conventional vector corresponding to the sub-synchronous oscillation, and output the sum of the required output sub-synchronous voltage and the conventional vector corresponding to the sub-synchronous oscillation to the SVPWM vector control to drive the IGBT of the 2MW doubly-fed converter connected to the power grid.

[0063] For example, Figure 3 Shown is a detailed flow chart of grid subsynchronous oscillation suppression for a doubly-fed converter.

[0064] For the doubly-fed generator, additional excitation damping is added similar to that of the synchronous generator. An additional excitation channel is added on the basis of conventional vector control. The channel output is superimposed on the conventional vector control output, and they work together to drive the corresponding phase IGBT through the PWM strategy.

[0065] The mechanism of suppressing subsynchronous resonance by additional damping control with rotor current as input signal: when subsynchronous resonance occurs, the subsynchronous voltage is output through the additional damping controller, and it is made to follow the subsynchronous current. Finally, the control system presents a positive resistance characteristic at the subsynchronous frequency, that is, the damping characteristic of Req is increased, thereby reducing the risk of subsynchronous resonance of the wind turbine.

[0066] A bandpass filter is used instead of a high-pass filter to filter the rotor current. The bandpass filter is used to extract the subsynchronous resonant current on the rotor dq axis. The additional damping controller increases the positive damping of the system by controlling the resonant current to achieve stable operation of the system.

[0067] The transfer function expression of the bandpass filter is: Where ω represents the resonant frequency to be extracted, ζ represents the damping coefficient, and the variable s comes from the Laplace transform, representing the frequency s=jω.

[0068] For example, when the wind turbine grid voltage undergoes subsynchronous resonance at a certain time, the grid-connected current will have a resonant current with a frequency of about 5Hz, which will be reflected on the dq axis on the rotor side, that is, a rotor disturbance current with a frequency of 45Hz will appear, and the power will also be disturbed by 45Hz. The filter frequency of BPF is set to 45Hz. A fixed 45Hz coordinate transformation is used to extract the 5Hz subsynchronous component of the stator reflected in the rotor current.

[0069] Through additional excitation damping control, the sub-synchronous frequency control signal on the generator rotor induces a component corresponding to the sub-synchronous frequency of the power grid in the stator magnetic field through the rotation of the rotor. The control effect is that the sub-synchronous current component of the stator output is 0, achieving the purpose of suppressing stator power pulsation and damping sub-synchronous oscillation of the power grid.

[0070] In summary, the method for suppressing subsynchronous oscillation of a power grid for a 2MW doubly-fed converter proposed in this embodiment can effectively suppress subsynchronous oscillation of the power grid and ensure safe and stable operation of the power grid.

[0071] Embodiment 2

[0072] Figure 4 FIG. 1 is a structural diagram of a grid subsynchronous oscillation suppression system for a 2MW doubly-fed converter according to an embodiment of the present application, such as Figure 4 As shown, the system comprises:

[0073] An acquisition module 100 is used to acquire a grid voltage and determine whether a subsynchronous oscillation occurs in the grid based on the grid voltage;

[0074] An extraction module 200 is used to obtain a conventional vector corresponding to the subsynchronous oscillation when the power grid has a subsynchronous oscillation, and to extract a subsynchronous resonant current on a dq axis of a generator rotor current;

[0075] A determination module 300, configured to determine a subsynchronous voltage required to be output by an additional damping controller according to the subsynchronous resonant current on the dq axis of the generator rotor current;

[0076] The control module 400 is used to control the IGBT of the 2MW doubly-fed converter connected to the power grid according to the normal vector corresponding to the sub-synchronous oscillation and the required output sub-synchronous voltage.

[0077] In the embodiment of the present disclosure, the acquisition module 100 is further used for:

[0078] Using a bandpass filter to perform real-time filtering on the grid voltage to obtain a low-frequency component of the grid voltage;

[0079] When the low-frequency component is greater than a preset first threshold, it is determined that subsynchronous oscillation occurs in the grid voltage.

[0080] In the embodiment of the present disclosure, the extraction module 200 is further used for:

[0081] Performing a dq transformation on the three-phase stator voltage of the grid voltage to obtain a stator voltage value corresponding to the subsynchronous oscillation;

[0082] Determining a rotor regulating voltage corresponding to the subsynchronous oscillation based on a rotor current reference value and a rotor current measured value of the generator;

[0083] Wherein, the conventional vector includes: rotor regulation voltage and stator voltage value.

[0084] Furthermore, the extraction module 200 is also used for:

[0085] A bandpass filter is used to extract the subsynchronous resonant current on the dq axis of the generator rotor current.

[0086] In the embodiment of the present disclosure, the control module 400 is further used for:

[0087] Determine the sum of the required output sub-synchronous voltage and the conventional vector corresponding to the sub-synchronous oscillation, and output the sum of the required output sub-synchronous voltage and the conventional vector corresponding to the sub-synchronous oscillation to the SVPWM vector control to drive the IGBT of the 2MW doubly-fed converter connected to the power grid.

[0088] In summary, the grid subsynchronous oscillation suppression system for a 2MW doubly-fed converter proposed in this embodiment can effectively suppress the grid subsynchronous oscillation and ensure the safe and stable operation of the grid.

[0089] Embodiment 3

[0090] In order to implement the above embodiments, the present disclosure further proposes an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method described in Embodiment 1 is implemented.

[0091] Embodiment 4

[0092] In order to implement the above embodiments, the present disclosure further proposes a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the method described in the first embodiment is implemented.

[0093] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0094] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0095] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for suppressing subsynchronous oscillation of a power grid for a 2MW doubly-fed converter, characterized in that: The method comprises: Acquiring a grid voltage, and determining whether subsynchronous oscillation occurs in the grid based on the grid voltage; When subsynchronous oscillation occurs in the power grid, a conventional vector corresponding to the subsynchronous oscillation is obtained, and a subsynchronous resonant current on a dq axis of a generator rotor current is extracted; Determining the subsynchronous voltage required to be output by the additional damping controller according to the subsynchronous resonant current on the dq axis of the generator rotor current; The IGBT of the 2MW double-fed converter connected to the power grid is controlled according to the conventional vector corresponding to the sub-synchronous oscillation and the required output sub-synchronous voltage.

2. The method according to claim 1, characterized in that The determining whether subsynchronous oscillation occurs in the power grid based on the power grid voltage includes: Using a bandpass filter to perform real-time filtering on the grid voltage to obtain a low-frequency component of the grid voltage; When the low-frequency component is greater than a preset first threshold, it is determined that subsynchronous oscillation occurs in the grid voltage.

3. The method according to claim 2, characterized in that The obtaining of the normal vector corresponding to the sub-synchronous oscillation includes: Performing a dq transformation on the three-phase stator voltage of the grid voltage to obtain a stator voltage value corresponding to the subsynchronous oscillation; Determining a rotor regulating voltage corresponding to the subsynchronous oscillation based on a rotor current reference value and a rotor current measured value of the generator; Wherein, the conventional vector includes: rotor regulation voltage and stator voltage value.

4. The method according to claim 3, characterized in that The step of extracting the subsynchronous resonant current on the dq axis of the generator rotor current comprises: A bandpass filter is used to extract the subsynchronous resonant current on the dq axis of the generator rotor current.

5. The method according to claim 4, characterized in that The controlling of the IGBT of the 2MW doubly-fed converter connected to the power grid according to the conventional vector corresponding to the sub-synchronous oscillation and the required output sub-synchronous voltage comprises: Determine the sum of the required output sub-synchronous voltage and the conventional vector corresponding to the sub-synchronous oscillation, and output the sum of the required output sub-synchronous voltage and the conventional vector corresponding to the sub-synchronous oscillation to the SVPWM vector control to drive the IGBT of the 2MW doubly-fed converter connected to the power grid.

6. A power grid subsynchronous oscillation suppression system for a 2MW doubly-fed converter, characterized in that: The system comprises: An acquisition module, used for acquiring a grid voltage, and judging whether a subsynchronous oscillation occurs in the grid based on the grid voltage; An extraction module, used for obtaining a conventional vector corresponding to the subsynchronous oscillation when the power grid has a subsynchronous oscillation, and extracting a subsynchronous resonant current on a dq axis of a generator rotor current; A determination module, used to determine the sub-synchronous voltage required to be output by the additional damping controller according to the sub-synchronous resonant current on the dq axis of the generator rotor current; A control module is used to control the IGBT of a 2MW double-fed converter connected to the power grid according to the conventional vector corresponding to the sub-synchronous oscillation and the required output sub-synchronous voltage.

7. The system according to claim 6, characterized in that The acquisition module is also used for: Using a bandpass filter to perform real-time filtering on the grid voltage to obtain a low-frequency component of the grid voltage; When the low-frequency component is greater than a preset first threshold, it is determined that subsynchronous oscillation occurs in the grid voltage.

8. The system according to claim 7, characterized in that The extraction module is also used for: Performing a dq transformation on the three-phase stator voltage of the grid voltage to obtain a stator voltage value corresponding to the subsynchronous oscillation; Determining a rotor regulating voltage corresponding to the subsynchronous oscillation based on a rotor current reference value and a rotor current measured value of the generator; Wherein, the conventional vector includes: rotor regulation voltage and stator voltage value.

9. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method according to any one of claims 1 to 5 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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