Output voltage control method and system of a self-synchronous voltage source grid-connected device

Abstract

The present invention relates to an output voltage control method and system of a self-synchronous voltage source grid-connected device, comprising: when the output power fluctuation value of a new energy voltage source of the self-synchronous voltage source grid-connected device exceeds a preset output power fluctuation threshold, determining a predicted value of a grid-connected point voltage at the next moment according to the port voltage, equivalent damping, output power of the new energy voltage source and the measured value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the current moment; controlling a DC bus voltage according to the predicted value of the grid-connected point voltage at the next moment to obtain an active power reference value of the self-synchronous voltage source grid-connected device; performing self-synchronous control according to the active power reference value to obtain a current reference value; performing deviation control according to the current reference value to obtain a control signal; performing pulse width modulation according to the control signal to obtain a modulation signal and sending it to a DC / DC converter to control the conduction time of an IGBT tube to achieve the stability of the output voltage of the self-synchronous voltage source grid-connected device.

Description

Technical Field

[0001] The present invention relates to the field of control technology of power electronic converters on the source side of a distribution network or a microgrid, and more specifically, to an output voltage control method and system of a self-synchronous voltage source grid-connected device. Background Art

[0002] With the continuous development of new energy power generation technology, high-proportion new energy systems are gradually put into construction. The increase in the connection of distributed power sources has led to a decrease in grid inertia. The intermittent and undispatched nature of new energy has also aggravated the voltage and frequency fluctuations of the grid. Based on the use of self-synchronization technology, a control strategy suitable for self-synchronization technology is proposed for the output power fluctuation of new energy power generation, which can effectively improve the stability of control.

[0003] At present, there is a self-synchronous voltage source grid-connected technology, which applies the electromagnetic equations and mechanical equations of synchronous generators to the design of power electronic converter control strategies, and adds "inertia" and "damping" to the traditional droop control. Under the control of this technology, the DC voltage source can show inertia characteristics and damping characteristics similar to those of the synchronous generator, effectively supporting the stability of the voltage and frequency of the power grid, and better responding to power grid failures. However, the existing methods generally set the inertia parameters and damping parameters in advance by comprehensively considering the specific conditions of the controlled system and the control performance requirements, and often do not have dynamic adjustment capabilities. They can well respond to relatively stable DC voltage sources, but new energy voltage sources, such as photovoltaics, often have output power that changes with environmental factors, and the voltage changes greatly. The impedance value between the new energy power source and the power grid will also fluctuate greatly, and the fixed damping parameters may cause the voltage at the grid connection point to exceed the limit, and cannot well respond to the adjustment of the frequency and voltage of the power grid. Therefore, it is necessary to adjust the self-synchronous grid-connected technology according to the fluctuations of new energy power sources.

[0004] In a high-proportion renewable energy power system, how to optimize the self-synchronous voltage source control strategy has attracted widespread attention in the industry. Therefore, a method for controlling a self-synchronous synchronous voltage source grid-connected device in a high-proportion renewable energy power system is needed. Summary of the invention

[0005] The present invention provides an output voltage control method and system of a self-synchronous voltage source grid-connected device to solve the problem of how to adjust the data voltage of the self-synchronous voltage source grid-connected device according to the fluctuation of a new energy power supply.

[0006] In order to solve the above problem, according to one aspect of the present invention, a method for controlling an output voltage of a self-synchronous voltage source grid-connected device is provided, the method comprising:

[0007] When the output power fluctuation value of the new energy voltage source of the self-synchronous voltage source grid-connected device exceeds a preset output power fluctuation threshold, a predicted value of the grid connection point voltage at the next moment is determined according to the port voltage of the new energy voltage source, the equivalent damping of the new energy voltage source, the output power of the new energy voltage source and the measured value of the grid connection point voltage of the self-synchronous voltage source grid-connected device at the current moment;

[0008] According to the predicted value of the grid connection point voltage at the next moment and the preset voltage reference value, the DC bus voltage is controlled to obtain the active power reference value of the self-synchronous voltage source grid connection device;

[0009] Performing self-synchronization control according to the active power reference value of the self-synchronous voltage source grid-connected device, the armature voltage of the DC generator, the mechanical torque of the DC generator, the electromagnetic torque of the DC generator and the mechanical angular velocity of the DC generator to obtain a current reference value;

[0010] Perform deviation control according to the current reference value and the sampled current value of the grid-connected point to obtain a control signal;

[0011] Pulse width modulation is performed according to the control signal to obtain a modulation signal, and the modulation signal is sent to a DC / DC converter to control the conduction time of an insulated gate bipolar transistor (IGBT) to achieve the stabilization of the output voltage of the self-synchronous voltage source grid-connected device.

[0012] Preferably, the step of determining the predicted value of the grid connection point voltage at the next moment according to the port voltage of the new energy voltage source, the equivalent damping of the new energy voltage source, the output power of the new energy voltage source and the measured value of the grid connection point voltage of the self-synchronous voltage source grid connection device at the current moment comprises:

[0013] U2(k+1)=U g (k)+D(k)P(k+1) / U2(k+1)≈U g (k)+D(k)P(k) / U2(k),

[0014] D(k)=(UU g (k))U / P(k),

[0015] Among them, U2(k+1) is the predicted value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the next time k+1; U2(k) is the measured value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the current time k; D(k) is the equivalent damping of the new energy voltage source at time k; P(k) is the output power of the new energy voltage source at time k; U g (k) is the terminal voltage of the new energy voltage source at time k; U is the output voltage value of the ideal new energy voltage source.

[0016] Preferably, the method further comprises:

[0017] The armature voltage of the DC generator is calculated in the following manner, including:

[0018] E=U2+IR a =C T φω,

[0019] The mechanical torque of the DC generator is calculated in the following manner, including:

[0020]

[0021] The electromagnetic torque of the DC generator is calculated in the following manner, including:

[0022]

[0023] The DC angular velocity of the DC generator is calculated using the following mechanical equations, including:

[0024]

[0025] Where, E is the armature voltage of the DC generator; C T is the torque coefficient; Φ is the magnetic flux; ω is the mechanical angular velocity of the DC generator; U2 is the grid voltage; R a is the armature resistance; T e and T m are the electromagnetic torque and mechanical torque of the DC generator respectively; P m is the active power reference value of the DC generator; H is the preset inertia coefficient; D is the equivalent damping of the new energy voltage source; ω0 is the rated mechanical angular velocity; I ref is the current reference value; Pe is the electromagnetic power of the DC generator.

[0026] Preferably, the modulation signal includes: a first modulation signal and a second modulation signal, and the IGBT tube includes: a first IGBT tube and a second IGBT tube.

[0027] Preferably, the method further comprises:

[0028] When the modulation signal is 1, the IGBT tube is controlled to be turned on; when the modulation signal is 0, the IGBT tube is controlled to be turned off.

[0029] According to another aspect of the present invention, an output voltage control system of a self-synchronous voltage source grid-connected device is provided, the system comprising:

[0030] A grid connection point voltage prediction unit, used to determine a predicted value of the grid connection point voltage at the next moment according to the port voltage of the new energy voltage source, the equivalent damping of the new energy voltage source, the output power of the new energy voltage source and the measured value of the grid connection point voltage of the self-synchronous voltage source grid connection device at the current moment, when the output power fluctuation value of the new energy voltage source of the self-synchronous voltage source grid connection device exceeds a preset output power fluctuation threshold;

[0031] A DC bus voltage control unit, used to compare and track the predicted value of the grid-connected point voltage at the next moment and a preset voltage reference value, control the DC bus voltage, and obtain an active power reference value of the self-synchronous voltage source grid-connected device;

[0032] A self-synchronous control unit, used for performing self-synchronous control according to an active power reference value of the self-synchronous voltage source grid-connected device, an armature voltage of the DC generator, a mechanical torque of the DC generator, an electromagnetic torque of the DC generator and a mechanical angular velocity of the DC generator, so as to obtain a current reference value;

[0033] A deviation control unit, used for performing deviation control according to the current reference value and the sampled current value of the grid-connected point to obtain a control signal;

[0034] The output voltage control unit is used to perform pulse width modulation according to the control signal to obtain a modulation signal, and send the modulation signal to the DC / DC converter to control the conduction time of the insulated gate bipolar transistor IGBT tube to achieve the stability of the output voltage of the self-synchronous voltage source grid-connected device.

[0035] Preferably, the grid connection point voltage prediction unit determines the predicted value of the grid connection point voltage at the next moment according to the port voltage of the new energy voltage source, the equivalent damping of the new energy voltage source, the output power of the new energy voltage source and the measured value of the grid connection point voltage of the self-synchronous voltage source grid connection device at the current moment, including:

[0036] U2(k+1)=U g (k)+D(k)P(k+1) / U2(k+1)≈U g (k)+D(k)P(k) / U2(k),

[0037] D(k)=(UU g (k))U / P(k),

[0038] Among them, U2(k+1) is the predicted value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the next time k+1; U2(k) is the measured value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the current time k; D(k) is the equivalent damping of the new energy voltage source at time k; P(k) is the output power of the new energy voltage source at time k; Ug (k) is the terminal voltage of the new energy voltage source at time k; U is the output voltage value of the ideal new energy voltage source.

[0039] Preferably, the system further comprises: a computing unit, configured to:

[0040] The armature voltage of the DC generator is calculated in the following manner, including:

[0041] E=U2+IR a =C T φω,

[0042] The mechanical torque of the DC generator is calculated in the following manner, including:

[0043]

[0044] The electromagnetic torque of the DC generator is calculated in the following manner, including:

[0045]

[0046] The DC angular velocity of the DC generator is calculated using the following mechanical equations, including:

[0047]

[0048] Where, E is the armature voltage of the DC generator; C T is the torque coefficient; Φ is the magnetic flux; ω is the mechanical angular velocity of the DC generator; U2 is the grid voltage; R a is the armature resistance; T e and T m are the electromagnetic torque and mechanical torque of the DC generator respectively; P m is the active power reference value of the DC generator; H is the preset inertia coefficient; D is the equivalent damping of the new energy voltage source; ω0 is the rated mechanical angular velocity; I ref is the current reference value; Pe is the electromagnetic power of the DC generator.

[0049] Preferably, the modulation signal includes: a first modulation signal and a second modulation signal, and the IGBT tube includes: a first IGBT tube and a second IGBT tube.

[0050] Preferably, the output voltage control unit further includes:

[0051] When the modulation signal is 1, the IGBT tube is controlled to be turned on; when the modulation signal is 0, the IGBT tube is controlled to be turned off.

[0052] The present invention provides an output voltage control method and system for a self-synchronous voltage source grid-connected device, which applies the mechanical equation and electromotive force balance equation of a DC generator to the self-synchronous voltage source control strategy, so that the voltage source exhibits the inertia characteristics and damping characteristics of the generator, better copes with the frequency fluctuation of the new energy power source, stabilizes the voltage, and improves the quality of electric energy. Compared with the existing self-synchronous voltage source control method, the method of the present invention can better control the new energy power source with large fluctuations, reduce the impact of the fluctuation on the power grid and microgrid when the power output power fluctuates, and better adapt to the power system with a high proportion of new energy access. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0054] Figure 1 is a flow chart of an output voltage control method 100 of a self-synchronous voltage source grid-connected device according to an embodiment of the present invention;

[0055] Figure 2 A schematic diagram of a model of a self-synchronous voltage source grid-connected device according to an embodiment of the present invention;

[0056] Figure 3 A flow chart of controlling the output voltage of a self-synchronous voltage source grid-connected device according to an embodiment of the present invention;

[0057] Figure 4 Schematic diagram of the structure of an output voltage control system 400 of a self-synchronous voltage source grid-connected device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0058] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0059] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0060] Figure 1 FIG. 1 is a flow chart of an output voltage control method 100 of a self-synchronous voltage source grid-connected device according to an embodiment of the present invention. Figure 1 As shown, the output voltage control method of the self-synchronous voltage source grid-connected device provided by the embodiment of the present invention applies the mechanical equation and electromotive force balance equation of the DC generator to the self-synchronous voltage source control strategy, so that the voltage source exhibits the inertia characteristics and damping characteristics of the generator, better copes with the frequency fluctuation of the new energy power source, stabilizes the voltage, and improves the quality of electric energy. Compared with the existing self-synchronous voltage source control method, the method of the present invention can better control the new energy power source with large fluctuations. When the power output power fluctuates, the impact of the fluctuation on the power grid and the microgrid is reduced, and the power system with a high proportion of new energy access is better adapted. The output voltage control method 100 of the self-synchronous voltage source grid-connected device provided by the embodiment of the present invention starts from step 101. In step 101, when the output power fluctuation value of the new energy voltage source of the self-synchronous voltage source grid-connected device exceeds the preset output power fluctuation threshold, the predicted value of the grid connection point voltage at the next moment is determined according to the port voltage of the new energy voltage source, the equivalent damping of the new energy voltage source, the output power of the new energy voltage source, and the measured value of the grid connection point voltage of the self-synchronous voltage source grid-connected device at the current moment.

[0061] Preferably, the step of determining the predicted value of the grid connection point voltage at the next moment according to the port voltage of the new energy voltage source, the equivalent damping of the new energy voltage source, the output power of the new energy voltage source and the measured value of the grid connection point voltage of the self-synchronous voltage source grid connection device at the current moment comprises:

[0062] U2(k+1)=U g (k)+D(k)P(k+1) / U2(k+1)≈U g (k)+D(k)P(k) / U2(k),

[0063] D(k)=(UU g (k))U / P(k),

[0064] Among them, U2(k+1) is the predicted value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the next time k+1; U2(k) is the measured value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the current time k; D(k) is the equivalent damping of the new energy voltage source at time k; P(k) is the output power of the new energy voltage source at time k; U g (k) is the terminal voltage of the new energy voltage source at time k; U is the output voltage value of the ideal new energy voltage source.

[0065] The model of the self-synchronous voltage source grid-connected device of the present invention is as follows Figure 2As shown, the synchronous voltage source device of the present invention includes a new energy voltage source and a DC / DC converter; the new energy voltage source can be equivalent to an ideal power supply, a voltage source internal resistance and a line impedance; the DC / DC converter topology adopts an isolated Buck / Boost converter; the input side of the DC / DC converter is connected to the new energy voltage source, and the output side outputs a DC voltage and is connected to a DC bus; the DC / DC converter adopts a self-synchronous control strategy and can simulate the operating characteristics of a DC generator.

[0066] In the present invention, the voltage relationship of the new energy voltage source itself is: U g =U-ΔU, where, U g is the port voltage of the new energy voltage source, obtained by sampling, U is the voltage value emitted by the ideal new energy voltage source, which is a known quantity, ΔU is the voltage source internal resistance and line impedance loss voltage, ΔU=DP / U, D is the port equivalent damping of the new energy voltage source, and P is the output power of the new energy voltage source. Therefore, the voltage at the grid connection point of the new energy voltage source can be expressed as: U=Ug+DP / U.

[0067] Therefore, the port equivalent damping D(k)=(UU g (k))U / P(k); where k represents the current moment. The present invention can calculate the equivalent damping change of the new energy voltage source in real time, better cope with the self-damping change caused by the output frequency of the voltage source, eliminate the inflexibility caused by the fixed damping parameters, and avoid possible voltage over-limit. To a certain extent, it optimizes the ability of the self-synchronous voltage source to cope with the fluctuation of the new energy power supply and stabilizes the bus voltage.

[0068] In the present invention, when the output power fluctuation value of the new energy voltage source of the self-synchronous voltage source grid-connected device exceeds the preset output power fluctuation threshold, the formula U2(k+1)=U g (k)+D(k)P(k+1) / U2(k+1)≈U g (k)+D(k)P(k) / U2(k), determine the predicted value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the next moment; wherein, U2(k+1) is the predicted value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the next moment k+1; U2(k) is the measured value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the current moment k; D(k) is the equivalent damping of the new energy voltage source at moment k; P(k) is the output power of the new energy voltage source at moment k; U g(k) is the port voltage of the new energy voltage source at time k; U is the ideal output voltage value of the new energy voltage source. By predicting the output voltage and predicting the frequency and voltage fluctuation of the new energy voltage source in advance, the self-synchronous voltage source grid-connected device can better lower the DC bus voltage fluctuation caused by the random fluctuation of new energy power generation on the basis of the original, and improve the power quality of the microgrid or distribution network.

[0069] In step 102, the DC bus voltage is controlled based on the predicted value of the grid-connected point voltage at the next moment and the preset voltage reference value, and the active power reference value of the self-synchronous voltage source grid-connected device is obtained.

[0070] Combination Figure 3 As shown, in the present invention, according to the predicted value U2(k+1) of the grid connection point voltage at the next moment and the preset voltage reference value U 2ref Comparative tracking is performed to control the DC bus voltage and obtain the active power reference value Pm of the self-synchronous voltage source grid-connected device.

[0071] In step 103, self-synchronization control is performed according to the active power reference value of the self-synchronous voltage source grid-connected device, the armature voltage of the DC generator, the mechanical torque of the DC generator, the electromagnetic torque of the DC generator and the mechanical angular velocity of the DC generator to obtain a current reference value.

[0072] Preferably, the method further comprises:

[0073] The armature voltage of the DC generator is calculated in the following manner, including:

[0074] E=U2+IR a =C T φω,

[0075] The mechanical torque of the DC generator is calculated in the following manner, including:

[0076]

[0077] The electromagnetic torque of the DC generator is calculated in the following manner, including:

[0078]

[0079] The DC angular velocity of the DC generator is calculated using the following mechanical equations, including:

[0080]

[0081] Where, E is the armature voltage of the DC generator; C T is the torque coefficient; Φ is the magnetic flux; ω is the mechanical angular velocity of the DC generator; U2 is the grid voltage; Ra is the armature resistance; T e and T m are the electromagnetic torque and mechanical torque of the DC generator respectively; P m is the active power reference value of the DC generator; H is the preset inertia coefficient; D is the equivalent damping of the new energy voltage source; ω0 is the rated mechanical angular velocity; I ref is the current reference value; Pe is the electromagnetic power of the DC generator.

[0082] In the present invention, the electromotive force balance equation of the DC generator armature circuit is:

[0083] E=U2+IR a =C T φω,

[0084] The calculation formula of the mechanical torque of the DC generator is:

[0085]

[0086] The calculation formula of the electromagnetic torque of the DC generator is:

[0087]

[0088] The mechanical equation is:

[0089]

[0090] Where, E is the armature voltage of the DC generator, which is obtained by calculation; C T is the torque coefficient; Φ is the magnetic flux; ω is the mechanical angular velocity of the DC generator, obtained by calculation; U2 is the grid connection point voltage; R a is the armature resistance; T e and T m are the electromagnetic torque and mechanical torque of the DC generator respectively; P m is the active power reference value of the DC generator; H is the preset inertia coefficient; D is the equivalent damping of the new energy voltage source; ω0 is the rated mechanical angular velocity; I ref is the current reference value, obtained by calculation; Pe is the electromagnetic power of the DC generator.

[0091] Combination Figure 3 As shown, in the present invention, after determining the active power reference value Pm of the self-synchronous voltage source grid-connected device, self-synchronous control is performed according to the active power reference value of the self-synchronous voltage source grid-connected device, the armature voltage of the DC generator, the mechanical torque of the DC generator, the electromagnetic torque of the DC generator and the mechanical angular velocity of the DC generator to obtain the current reference value I ref .

[0092] In step 104, deviation control is performed according to the current reference value and the sampled current value of the grid-connected point to obtain a control signal.

[0093] In step 105, pulse width modulation is performed according to the control signal to obtain a modulation signal, and the modulation signal is sent to the DC / DC converter to control the conduction time of the insulated gate bipolar transistor IGBT tube to achieve the stability of the output voltage of the self-synchronous voltage source grid-connected device.

[0094] Preferably, the modulation signal includes: a first modulation signal and a second modulation signal, and the IGBT tube includes: a first IGBT tube and a second IGBT tube.

[0095] Preferably, the method further comprises:

[0096] When the modulation signal is 1, the IGBT tube is controlled to be turned on; when the modulation signal is 0, the IGBT tube is controlled to be turned off.

[0097] Combination Figure 2 and Figure 3 As shown, in the present invention, after determining the current reference value I ref After that, deviation control is performed according to the current reference value and the sampling current value I2 of the grid-connected point to obtain a control signal. Pulse width modulation is then performed according to the control signal to obtain modulation signals S1 and S2, and the modulation signals S1 and S2 are sent to the DC / DC converter to control the conduction time of the insulated gate bipolar transistor IGBT tube. When the modulation signal is 1, the IGBT tube is controlled to be turned on; when the modulation signal is 0, the IGBT tube is controlled to be turned off, thereby achieving the stability of the output voltage of the self-synchronous voltage source grid-connected device.

[0098] The output voltage control method of the self-synchronous voltage source grid-connected device of the present invention generates a modulation signal through DC bus voltage control, virtual DC generator control, current deviation control and pulse width modulation, and acts on the DC / DC converter to control the on and off of the IGBT tube, thereby achieving the stability of the output voltage of the self-synchronous voltage source grid-connected device; the method of the present invention can predict the damping change between the new energy voltage source and the grid, and adjust the damping parameters in the self-synchronous control method in time, so that the control method is more flexible, and when facing large frequency fluctuations of the new energy power source, it can recover to a normal state more quickly, reducing the impact of voltage and frequency fluctuations on the power grid and microgrid.

[0099] Figure 4 FIG. 4 is a schematic diagram of the structure of an output voltage control system 400 of a self-synchronous voltage source grid-connected device according to an embodiment of the present invention. Figure 4As shown, the output voltage control system 400 of the self-synchronous voltage source grid-connected device provided in an embodiment of the present invention includes: a grid-connected point voltage prediction unit 401, a DC bus voltage control unit 402, a self-synchronous control unit 403, a deviation control unit 404 and an output voltage control unit 405.

[0100] Preferably, the grid connection point voltage prediction unit 401 is used to determine the predicted value of the grid connection point voltage at the next moment according to the port voltage of the new energy voltage source, the equivalent damping of the new energy voltage source, the output power of the new energy voltage source and the actual measured value of the grid connection point voltage of the self-synchronous voltage source grid-connected device at the current moment when the output power fluctuation value of the new energy voltage source of the self-synchronous voltage source grid-connected device exceeds a preset output power fluctuation threshold.

[0101] Preferably, the grid connection point voltage prediction unit 401 determines the predicted value of the grid connection point voltage at the next moment according to the port voltage of the new energy voltage source, the equivalent damping of the new energy voltage source, the output power of the new energy voltage source and the measured value of the grid connection point voltage of the self-synchronous voltage source grid connection device at the current moment, including:

[0102] U2(k+1)=U g (k)+D(k)P(k+1) / U2(k+1)≈U g (k)+D(k)P(k) / U2(k),

[0103] D(k)=(UU g (k))U / P(k),

[0104] Among them, U2(k+1) is the predicted value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the next time k+1; U2(k) is the measured value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the current time k; D(k) is the equivalent damping of the new energy voltage source at time k; P(k) is the output power of the new energy voltage source at time k; U g (k) is the terminal voltage of the new energy voltage source at time k; U is the output voltage value of the ideal new energy voltage source.

[0105] Preferably, the DC bus voltage control unit 402 is used to compare and track the predicted value of the grid-connected point voltage at the next moment and a preset voltage reference value, control the DC bus voltage, and obtain the active power reference value of the self-synchronous voltage source grid-connected device.

[0106] Preferably, the self-synchronization control unit 403 is used to perform self-synchronization control according to the active power reference value of the self-synchronous voltage source grid-connected device, the armature voltage of the DC generator, the mechanical torque of the DC generator, the electromagnetic torque of the DC generator and the mechanical angular velocity of the DC generator to obtain a current reference value.

[0107] Preferably, the system further comprises: a computing unit, configured to:

[0108] The armature voltage of the DC generator is calculated in the following manner, including:

[0109] E=U2+IR a =C T φω,

[0110] The mechanical torque of the DC generator is calculated in the following manner, including:

[0111]

[0112] The electromagnetic torque of the DC generator is calculated in the following manner, including:

[0113]

[0114] The DC angular velocity of the DC generator is calculated using the following mechanical equations, including:

[0115]

[0116] Where, E is the armature voltage of the DC generator; C T is the torque coefficient; Φ is the magnetic flux; ω is the mechanical angular velocity of the DC generator; U2 is the grid voltage; R a is the armature resistance; T e and T m are the electromagnetic torque and mechanical torque of the DC generator respectively; P m is the active power reference value of the DC generator; H is the preset inertia coefficient; D is the equivalent damping of the new energy voltage source; ω0 is the rated mechanical angular velocity; I ref is the current reference value; Pe is the electromagnetic power of the DC generator.

[0117] Preferably, the deviation control unit 404 is used to perform deviation control according to the current reference value and the sampled current value of the grid-connected point to obtain a control signal.

[0118] Preferably, the output voltage control unit 405 is used to perform pulse width modulation according to the control signal to obtain a modulation signal, and send the modulation signal to the DC / DC converter to control the conduction time of the insulated gate bipolar transistor IGBT tube to achieve the stability of the output voltage of the self-synchronous voltage source grid-connected device.

[0119] Preferably, the modulation signal includes: a first modulation signal and a second modulation signal, and the IGBT tube includes: a first IGBT tube and a second IGBT tube.

[0120] Preferably, the output voltage control unit further includes:

[0121] When the modulation signal is 1, the IGBT tube is controlled to be turned on; when the modulation signal is 0, the IGBT tube is controlled to be turned off.

[0122] The output voltage control system 400 of the self-synchronous voltage source grid-connected device of the embodiment of the present invention corresponds to the output voltage control method 100 of the self-synchronous voltage source grid-connected device of another embodiment of the present invention, and will not be described in detail here.

[0123] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0124] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / said / the [means, components, etc.]" are to be openly interpreted as at least one instance of the means, components, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed, unless explicitly stated otherwise.

[0125] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0126] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0127] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0128] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for controlling the output voltage of a self-synchronous voltage source grid-connected device, characterized in that: The method comprises: When the output power fluctuation value of the new energy voltage source of the self-synchronous voltage source grid-connected device exceeds a preset output power fluctuation threshold, a predicted value of the grid connection point voltage at the next moment is determined according to the port voltage of the new energy voltage source, the equivalent damping of the new energy voltage source, the output power of the new energy voltage source and the measured value of the grid connection point voltage of the self-synchronous voltage source grid-connected device at the current moment; According to the predicted value of the grid connection point voltage at the next moment and the preset voltage reference value, the DC bus voltage is controlled to obtain the active power reference value of the self-synchronous voltage source grid connection device; Performing self-synchronization control according to the active power reference value of the self-synchronous voltage source grid-connected device, the armature voltage of the DC generator, the mechanical torque of the DC generator, the electromagnetic torque of the DC generator and the mechanical angular velocity of the DC generator to obtain a current reference value; Perform deviation control according to the current reference value and the sampled current value of the grid-connected point to obtain a control signal; Performing pulse width modulation according to the control signal to obtain a modulation signal, and sending the modulation signal to a DC / DC converter to control the conduction time of an insulated gate bipolar transistor (IGBT) to achieve the stability of the output voltage of the self-synchronous voltage source grid-connected device; The method of determining the predicted value of the grid connection point voltage at the next moment according to the port voltage of the new energy voltage source, the equivalent damping of the new energy voltage source, the output power of the new energy voltage source and the measured value of the grid connection point voltage of the self-synchronous voltage source grid connection device at the current moment comprises: U2(k+1)=U g (k)+D(k)P(k+1) / U2(k+1)≈U g (k)+D(k)P(k) / U2(k), D(k)=(UU g (k))U / P(k), Among them, U2(k+1) is the predicted value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the next time k+1; U2(k) is the measured value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the current time k; D(k) is the equivalent damping of the new energy voltage source at time k; P(k) is the output power of the new energy voltage source at time k; U g (k) is the terminal voltage of the new energy voltage source at time k; U is the output voltage value of the ideal new energy voltage source.

2. The method according to claim 1, characterized in that The method further comprises: The armature voltage of the DC generator is calculated in the following manner, including: E=U2+IR a =C T light, The mechanical torque of the DC generator is calculated in the following manner, including: The electromagnetic torque of the DC generator is calculated in the following manner, including: The DC angular velocity of the DC generator is calculated using the following mechanical equations, including: Where, E is the armature voltage of the DC generator; C T is the torque coefficient; Φ is the magnetic flux; ω is the mechanical angular velocity of the DC generator; U2 is the grid connection point voltage; R a is the armature resistance; T e and T m are the electromagnetic torque and mechanical torque of the DC generator respectively; P m is the active power reference value of the DC generator; H is the preset inertia coefficient; D is the equivalent damping of the new energy voltage source; ω0 is the rated mechanical angular velocity; I ref is the current reference value; Pe is the electromagnetic power of the DC generator.

3. The method according to claim 1, characterized in that The modulation signal includes: a first modulation signal and a second modulation signal, and the IGBT tube includes: a first IGBT tube and a second IGBT tube.

4. The method according to claim 1, characterized in that The method further comprises: When the modulation signal is 1, the IGBT tube is controlled to be turned on; when the modulation signal is 0, the IGBT tube is controlled to be turned off.

5. An output voltage control system of a self-synchronous voltage source grid-connected device, characterized in that: The system comprises: A grid connection point voltage prediction unit, used to determine a predicted value of the grid connection point voltage at the next moment according to the port voltage of the new energy voltage source, the equivalent damping of the new energy voltage source, the output power of the new energy voltage source and the measured value of the grid connection point voltage of the self-synchronous voltage source grid connection device at the current moment, when the output power fluctuation value of the new energy voltage source of the self-synchronous voltage source grid connection device exceeds a preset output power fluctuation threshold; A DC bus voltage control unit, used to compare and track the predicted value of the grid-connected point voltage at the next moment and a preset voltage reference value, control the DC bus voltage, and obtain an active power reference value of the self-synchronous voltage source grid-connected device; A self-synchronous control unit, used for performing self-synchronous control according to an active power reference value of the self-synchronous voltage source grid-connected device, an armature voltage of the DC generator, a mechanical torque of the DC generator, an electromagnetic torque of the DC generator and a mechanical angular velocity of the DC generator, so as to obtain a current reference value; A deviation control unit, used for performing deviation control according to the current reference value and the sampled current value of the grid-connected point to obtain a control signal; An output voltage control unit, used for performing pulse width modulation according to the control signal to obtain a modulation signal, and sending the modulation signal to the DC / DC converter to control the conduction time of the insulated gate bipolar transistor IGBT tube to achieve the stability of the output voltage of the self-synchronous voltage source grid-connected device; The grid connection point voltage prediction unit determines the predicted value of the grid connection point voltage at the next moment according to the port voltage of the new energy voltage source, the equivalent damping of the new energy voltage source, the output power of the new energy voltage source and the measured value of the grid connection point voltage of the self-synchronous voltage source grid connection device at the current moment, including: U2(k+1)=U g (k)+D(k)P(k+1) / U2(k+1)≈U g (k)+D(k)P(k) / U2(k), D(k)=(UU g (k))U / P(k), Among them, U2(k+1) is the predicted value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the next time k+1; U2(k) is the measured value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at the current time k; D(k) is the equivalent damping of the new energy voltage source at time k; P(k) is the output power of the new energy voltage source at time k; U g (k) is the terminal voltage of the new energy voltage source at time k; U is the output voltage value of the ideal new energy voltage source.

6. The system according to claim 5, characterized in that The system further comprises: a computing unit, configured to: The armature voltage of the DC generator is calculated in the following manner, including: E=U2+IR a =C T light, The mechanical torque of the DC generator is calculated in the following manner, including: The electromagnetic torque of the DC generator is calculated in the following manner, including: The DC angular velocity of the DC generator is calculated using the following mechanical equations, including: Where, E is the armature voltage of the DC generator; C T is the torque coefficient; Φ is the magnetic flux; ω is the mechanical angular velocity of the DC generator; U2 is the grid voltage; R a is the armature resistance; T e and T m are the electromagnetic torque and mechanical torque of the DC generator respectively; P m is the active power reference value of the DC generator; H is the preset inertia coefficient; D is the equivalent damping of the new energy voltage source; ω0 is the rated mechanical angular velocity; I ref is the current reference value; Pe is the electromagnetic power of the DC generator.

7. The system according to claim 5, characterized in that The modulation signal includes: a first modulation signal and a second modulation signal, and the IGBT tube includes: a first IGBT tube and a second IGBT tube.

8. The system according to claim 5, characterized in that The output voltage control unit further includes: When the modulation signal is 1, the IGBT tube is controlled to be turned on; when the modulation signal is 0, the IGBT tube is controlled to be turned off.

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