CN113258556A - Output voltage control method and system of self-synchronizing voltage source grid-connected device - Google Patents
Output voltage control method and system of self-synchronizing voltage source grid-connected device Download PDFInfo
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Abstract
The invention relates to an output voltage control method and system of a self-synchronizing voltage source grid-connected device, comprising the following steps: when the output power fluctuation value of the new energy voltage source of the self-synchronizing voltage source grid-connected device exceeds a preset output power fluctuation threshold value, determining a predicted value of the grid-connected point voltage at the next moment according to the port voltage, the equivalent damping and the output power of the new energy voltage source and the measured value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the current moment; controlling the voltage of the direct current bus according to the predicted value of the grid-connected point voltage at the next moment, and acquiring an active power reference value of a self-synchronizing voltage source grid-connected device; performing self-synchronization 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; and performing pulse width modulation according to the control signal to obtain a modulation signal and sending the modulation signal to the DC/DC converter so as to control the conduction time of the IGBT tube and realize the stabilization of the output voltage of the self-synchronizing voltage source grid-connected device.
Description
Technical Field
The invention relates to the technical field of control of power electronic converters on the source side of a power distribution network or a micro-grid, in particular to an output voltage control method and system of a self-synchronizing voltage source grid-connected device.
Background
With the continuous development of new energy power generation technology, a high-proportion new energy system is gradually put into construction, the grid connection of distributed power sources is increased, so that the inertia of a power grid is reduced, and the voltage and frequency fluctuation of the power grid is also aggravated by the intermittence and the non-schedulability of new energy. On the basis of the self-synchronizing technology, a control strategy suitable for the self-synchronizing technology is provided for the power generation output power fluctuation of the new energy, and the control stability can be effectively improved.
At present, a self-synchronous voltage source grid-connected technology is available, in the technology, an electromagnetic equation and a mechanical equation of a synchronous generator are applied to the design of a power electronic converter control strategy, inertia and damping are added in the traditional droop control, and under the control of the technology, a direct-current voltage source can show inertia characteristics and damping characteristics similar to those of the synchronous generator, so that the voltage and frequency of a power grid are effectively supported to be stable, and the power grid fault can be better responded. However, the existing methods generally consider the specific conditions of the controlled system and the control performance requirements comprehensively to set the inertia parameters and the damping parameters in advance, and often do not have dynamic adjustment capability, and can well cope with a relatively stable direct current voltage source, but a new energy source voltage source, such as: the output power of photovoltaic and the like often changes along with the change of environmental factors, the voltage change is large, the impedance value between a new energy power supply and a power grid also fluctuates greatly, and the fixed damping parameters may cause the problems that the voltage of a grid-connected point exceeds the limit and the like, so that the adjustment of the frequency and the voltage of the power grid cannot be well coped with. Therefore, the self-synchronization grid-connection technology needs to be adjusted according to the fluctuation of the new energy power supply.
In a high-proportion new energy power system, how to optimize a self-synchronous voltage source control strategy has attracted extensive attention in the industry. Therefore, a method for controlling a self-synchronous voltage source grid-connected device in a high-proportion new energy power system is needed.
Disclosure of Invention
The invention provides an output voltage control method and system of a self-synchronizing voltage source grid-connected device, and aims to solve the problem of how to adjust the data voltage of the self-synchronizing voltage source grid-connected device according to the fluctuation of a new energy power source.
In order to solve the above problem, according to an aspect of the present invention, there is provided an output voltage control method of a self-synchronizing voltage source grid-connected device, the method including:
when the output power fluctuation value of a new energy voltage source of the self-synchronizing voltage source grid-connected device exceeds a preset output power fluctuation threshold value, determining a predicted value of the grid-connected 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-connected point voltage of the self-synchronizing voltage source grid-connected device at the current moment;
comparing and tracking the predicted value of the grid-connected point voltage at the next moment with a preset voltage reference value, controlling the direct current bus voltage, and acquiring an active power reference value of the self-synchronizing voltage source grid-connected device;
performing self-synchronization control according to the active power reference value of the self-synchronization voltage source grid-connected device, the armature voltage of the direct current generator, the mechanical torque of the direct current generator, the electromagnetic torque of the direct current generator and the mechanical angular speed of the direct current generator to obtain a current reference value;
performing deviation control according to the current reference value and the sampling current value of the grid-connected point to obtain a control signal;
and 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) tube, so as to realize the stability of the output voltage of the self-synchronizing voltage source grid-connected device.
Preferably, the determining a predicted value of a grid-connected point voltage at a next time according to a port voltage of a new energy voltage source, an equivalent damping of the new energy voltage source, an output power of the new energy voltage source and an actual measured value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the current time includes:
U2(k+1)＝Ug(k)+D(k)P(k+1)/U2(k+1)≈Ug(k)+D(k)P(k)/U2(k)，
D(k)＝(U-Ug(k))U/P(k)，
wherein, U2(k +1) is a predicted value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the next moment k + 1; u shape2(k) The measured value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the current moment k is obtained; d (k) is the equivalent damping of the new energy voltage source at the moment k; p (k) is the output power of the new energy source voltage source at the moment k; u shapeg(k) The port voltage of the new energy source voltage source at the moment k; u is the sending voltage value of the ideal new energy source voltage source.
Preferably, wherein the method further comprises:
calculating an armature voltage of the DC generator using:
E＝U2+IRa＝CTφω，
calculating the mechanical torque of the DC generator by using the following method:
calculating the electromagnetic torque of the DC generator by the following method:
calculating the DC angular velocity of the DC generator using the following mechanical equations, including:
wherein E is the armature voltage of the direct current generator; cTIs a torque coefficient; phi is magnetic flux; omega is the mechanical angular speed of the direct current generator; u shape2Is the grid-connected point voltage; raIs an armature resistance; t iseAnd TmElectromagnetic torque and mechanical torque of the direct current generator are respectively; pmThe active power reference value of the direct current generator; h is a preset inertia coefficient; d is the equivalent damping of the new energy source voltage source; omega0Is a rated mechanical angular velocity; i isrefIs a current reference value; pe is the electromagnetic power of the DC generator.
Preferably, the modulation signal comprises: the IGBT tube comprises a first modulation signal and a second modulation signal, and comprises: the IGBT device comprises a first IGBT tube and a second IGBT tube.
Preferably, wherein the method further comprises:
when the modulation signal is 1, controlling the IGBT tube to be conducted; and when the modulation signal is 0, controlling the IGBT tube to be disconnected.
According to another aspect of the present invention, there is provided an output voltage control system of a self-synchronizing voltage source grid-connected device, the system comprising:
the grid-connected point voltage prediction unit is used for determining a predicted value of the grid-connected 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-connected 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;
the direct current bus voltage control unit is used for comparing and tracking the predicted value of the grid-connected point voltage at the next moment with a preset voltage reference value, controlling the direct current bus voltage and obtaining an active power reference value of the self-synchronizing voltage source grid-connected device;
the self-synchronization control unit is used for carrying out self-synchronization control according to the active power reference value of the self-synchronization voltage source grid-connected device, the armature voltage of the direct current generator, the mechanical torque of the direct current generator, the electromagnetic torque of the direct current generator and the mechanical angular speed of the direct current generator so as to obtain a current reference value;
the deviation control unit is used for carrying out deviation control according to the current reference value and the sampling current value of the grid-connected point so as to obtain a control signal;
and the output voltage control unit is used for carrying out pulse width modulation according to the control signal so as to obtain a modulation signal, and sending the modulation signal to the DC/DC converter so as to control the conduction time of the IGBT tube and realize the stabilization of the output voltage of the self-synchronizing voltage source grid-connected device.
Preferably, the grid-connected point voltage predicting unit determines a predicted value of a next-time grid-connected point voltage according to a port voltage of a new energy voltage source, an equivalent damping of the new energy voltage source, an output power of the new energy voltage source, and an actual measured value of a grid-connected point voltage of the self-synchronizing voltage source grid-connected device at a current time, and includes:
U2(k+1)＝Ug(k)+D(k)P(k+1)/U2(k+1)≈Ug(k)+D(k)P(k)/U2(k)，
D(k)＝(U-Ug(k))U/P(k)，
wherein, U2(k +1) is a predicted value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the next moment k + 1; u shape2(k) The measured value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the current moment k is obtained; d (k) is the equivalent damping of the new energy voltage source at the moment k; p (k) is new energy at time kThe output power of the source voltage source; u shapeg(k) The port voltage of the new energy source voltage source at the moment k; u is the sending voltage value of the ideal new energy source voltage source.
Preferably, wherein the system further comprises: a computing unit to:
calculating an armature voltage of the DC generator using:
E＝U2+IRa＝CTφω，
calculating the mechanical torque of the DC generator by using the following method:
calculating the electromagnetic torque of the DC generator by the following method:
calculating the DC angular velocity of the DC generator using the following mechanical equations, including:
wherein E is the armature voltage of the direct current generator; cTIs a torque coefficient; phi is magnetic flux; omega is the mechanical angular speed of the direct current generator; u shape2Is the grid-connected point voltage; raIs an armature resistance; t iseAnd TmElectromagnetic torque and mechanical torque of the direct current generator are respectively; pmThe active power reference value of the direct current generator; h is a preset inertia coefficient; d is the equivalent damping of the new energy source voltage source; omega0Is a rated mechanical angular velocity; i isrefIs a current reference value; pe is the electromagnetic power of the DC generator.
Preferably, the modulation signal comprises: the IGBT tube comprises a first modulation signal and a second modulation signal, and comprises: the IGBT device comprises a first IGBT tube and a second IGBT tube.
Preferably, the output voltage control unit further includes:
when the modulation signal is 1, controlling the IGBT tube to be conducted; and when the modulation signal is 0, controlling the IGBT tube to be disconnected.
The invention provides an output voltage control method and system of a self-synchronizing voltage source grid-connected device, which apply a mechanical equation and an electromotive force balance equation of a direct current generator to a self-synchronizing voltage source control strategy, so that a voltage source presents inertia characteristics and damping characteristics of the generator, frequency fluctuation of a new energy source power source is better responded, voltage is stabilized, and electric energy quality is improved. Compared with the existing self-synchronizing voltage source control method, the method can better control the new energy source with larger fluctuation, reduces the impact of the fluctuation on a power grid and a microgrid when the output power of the power source fluctuates, and is better suitable for a power system with high-proportion new energy source access.
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A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
fig. 1 is a flowchart of an output voltage control method 100 of a self-synchronous voltage source grid-connected device according to an embodiment of the invention;
FIG. 2 is a schematic diagram of a model of a self-synchronous voltage source grid-connected device according to an embodiment of the invention;
FIG. 3 is a flow chart of controlling the output voltage of the self-synchronizing voltage source grid-connected device according to the embodiment of the invention;
fig. 4 is a schematic structural diagram 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
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flowchart of an output voltage control method 100 of a self-synchronous voltage source grid-connected device according to an embodiment of the present invention. As shown in fig. 1, in the output voltage control method of the self-synchronous voltage source grid-connected device provided by the embodiment of the present invention, a mechanical equation and an electromotive force balance equation of a dc generator are applied to a self-synchronous voltage source control strategy, so that a voltage source exhibits an inertia characteristic and a damping characteristic of the generator, frequency fluctuation of a new energy power source is better handled, voltage is stabilized, and power quality is improved. Compared with the existing self-synchronizing voltage source control method, the method can better control the new energy source with larger fluctuation, reduces the impact of the fluctuation on a power grid and a microgrid when the output power of the power source fluctuates, and is better suitable for a power system with high-proportion new energy source access. The output voltage control method 100 of the self-synchronizing voltage source grid-connected device provided by the embodiment of the invention starts from step 101, and when the output power fluctuation value of the new energy voltage source of the self-synchronizing voltage source grid-connected device exceeds the preset output power fluctuation threshold value in step 101, the predicted value of the grid-connected 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-connected point voltage of the self-synchronizing voltage source grid-connected device at the current moment.
Preferably, the determining a predicted value of a grid-connected point voltage at a next time according to a port voltage of a new energy voltage source, an equivalent damping of the new energy voltage source, an output power of the new energy voltage source and an actual measured value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the current time includes:
U2(k+1)＝Ug(k)+D(k)P(k+1)/U2(k+1)≈Ug(k)+D(k)P(k)/U2(k)，
D(k)＝(U-Ug(k))U/P(k)，
wherein, U2(k +1) is a predicted value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the next moment k + 1; u shape2(k) The measured value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the current moment k is obtained; d (k) is the equivalent damping of the new energy voltage source at the moment k; p (k) is the output power of the new energy source voltage source at the moment k; u shapeg(k) The port voltage of the new energy source voltage source at the moment k; u is the sending voltage value of the ideal new energy source voltage source.
The model of the self-synchronizing voltage source grid-connected device is shown in fig. 2, and the self-synchronizing voltage source grid-connected device comprises a new energy source voltage source and a DC/DC converter; the new energy source voltage source can be equivalent to an ideal power source, the internal resistance of the voltage source and the line impedance; the topology of the DC/DC converter adopts an isolated Buck/Boost converter; the input side of the DC/DC converter is connected with a new energy source voltage source, the output side of the DC/DC converter outputs direct current voltage, and the direct current voltage is connected with a direct current bus; the DC/DC converter adopts a self-synchronizing control strategy, and can simulate the running characteristics of the direct-current generator.
In the invention, the voltage relationship of the new energy source voltage source is as follows: u shapegU- Δ U, wherein UgThe port voltage of the new energy source voltage source is obtained through sampling, U is an ideal voltage value sent out by the new energy source voltage source and is a known value, delta U is the internal resistance of the voltage source and the line impedance loss voltage, delta U is DP/U, D is the port equivalent damping of the new energy source voltage source, and P is the output power of the new energy source voltage source. Therefore, the voltage of the grid-connected point of the new energy source voltage source can be represented as: u is Ug + DP/U.
Thus, the port equivalent damping d (k) ═ U-U can be derivedg(k) U/P (k); where k denotes the current time. The method can calculate the equivalent damping change of the new energy voltage source in real time and better cope with the output frequency of the voltage sourceThe self damping change caused by the self damping change eliminates the inflexible problem caused by the fixed damping parameter, can also avoid the voltage overrun possibly generated, optimizes the capability of the self-synchronizing voltage source for coping with the new energy power supply fluctuation to a certain extent, and stabilizes the bus voltage.
In the invention, when the output power fluctuation value of the new energy voltage source of the self-synchronizing voltage source grid-connected device exceeds the preset output power fluctuation threshold value, a formula U is utilized2(k+1)＝Ug(k)+D(k)P(k+1)/U2(k+1)≈Ug(k)+D(k)P(k)/U2(k) Determining a predicted value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the next moment; wherein, U2(k +1) is a predicted value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the next moment k + 1; u shape2(k) The measured value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the current moment k is obtained; d (k) is the equivalent damping of the new energy voltage source at the moment k; p (k) is the output power of the new energy source voltage source at the moment k; u shapeg(k) The port voltage of the new energy source voltage source at the moment k; u is the sending voltage value of the ideal new energy source voltage source. By predicting the output voltage and predicting the frequency and voltage fluctuation of the new energy voltage source in advance, the voltage fluctuation of the direct-current bus caused by random fluctuation of new energy power generation can be better lower than that of the self-synchronizing voltage source grid-connected device on the original basis, and the electric energy quality of the micro-grid or the distribution network is improved.
And 102, comparing and tracking the predicted value of the grid-connected point voltage at the next moment with a preset voltage reference value, controlling the direct current bus voltage, and acquiring an active power reference value of the self-synchronizing voltage source grid-connected device.
Referring to FIG. 3, in the present invention, the predicted value U of the dot voltage at the next time is used2(k +1) and a preset voltage reference value U2refAnd performing comparison tracking, controlling the voltage of the direct current bus, and acquiring an active power reference value Pm of the self-synchronizing voltage source grid-connected device.
In step 103, self-synchronizing control is performed according to the active power reference value of the self-synchronizing voltage source grid-connected device, the armature voltage of the direct current generator, the mechanical torque of the direct current generator, the electromagnetic torque of the direct current generator and the mechanical angular velocity of the direct current generator to obtain a current reference value.
Preferably, wherein the method further comprises:
calculating an armature voltage of the DC generator using:
E＝U2+IRa＝CTφω，
calculating the mechanical torque of the DC generator by using the following method:
calculating the electromagnetic torque of the DC generator by the following method:
calculating the DC angular velocity of the DC generator using the following mechanical equations, including:
wherein E is the armature voltage of the direct current generator; cTIs a torque coefficient; phi is magnetic flux; omega is the mechanical angular speed of the direct current generator; u shape2Is the grid-connected point voltage; raIs an armature resistance; t iseAnd TmElectromagnetic torque and mechanical torque of the direct current generator are respectively; pmThe active power reference value of the direct current generator; h is a preset inertia coefficient; d is the equivalent damping of the new energy source voltage source; omega0Is a rated mechanical angular velocity; i isrefIs a current reference value; pe is the electromagnetic power of the DC generator.
In the invention, the electromotive force balance equation of the armature loop of the direct current generator is as follows:
E＝U2+IRa＝CTφω，
the calculation formula of the mechanical torque of the direct current generator is as follows:
the calculation formula of the electromagnetic torque of the direct current generator is as follows:
the mechanical equation is:
wherein E is the armature voltage of the direct current generator and is obtained through calculation; cTIs a torque coefficient; phi is magnetic flux; omega is the mechanical angular speed of the direct current generator and is obtained through calculation; u shape2Is the grid-connected point voltage; raIs an armature resistance; t iseAnd TmElectromagnetic torque and mechanical torque of the direct current generator are respectively; pmThe active power reference value of the direct current generator; h is a preset inertia coefficient; d is the equivalent damping of the new energy source voltage source; omega0Is a rated mechanical angular velocity; i isrefThe current reference value is obtained by calculation; pe is the electromagnetic power of the DC generator.
Referring to fig. 3, in the present invention, after determining the active power reference value Pm of the self-synchronous voltage source grid-connected device, self-synchronization control is performed according to the active power reference value Pm 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 Iref。
In step 104, deviation control is performed according to the current reference value and the sampling current value of the grid-connected point to obtain a control signal.
In step 105, 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 on-time of the IGBT, so as to stabilize the output voltage of the self-synchronizing voltage source grid-connected device.
Preferably, the modulation signal comprises: the IGBT tube comprises a first modulation signal and a second modulation signal, and comprises: the IGBT device comprises a first IGBT tube and a second IGBT tube.
Preferably, wherein the method further comprises:
when the modulation signal is 1, controlling the IGBT tube to be conducted; and when the modulation signal is 0, controlling the IGBT tube to be disconnected.
Referring to fig. 2 and 3, in the present invention, the current reference value I is determinedrefThen, according to the current reference value and the sampling current value I of the grid-connected point2Deviation control is performed to obtain a control signal. Then, according to the control signal, pulse width modulation is carried out to obtain a modulation signal S1And S2And modulating the modulated signal S1And S2Sending the signal to a DC/DC converter to control the conduction time of an Insulated Gate Bipolar Transistor (IGBT) tube, and controlling the IGBT tube to be conducted when the modulation signal is 1; and when the modulation signal is 0, controlling the IGBT tube to be disconnected, thereby realizing the stabilization of the output voltage of the self-synchronizing voltage source grid-connected device.
The output voltage control method of the self-synchronizing voltage source grid-connected device generates a modulation signal through direct current bus voltage control, virtual direct current generator control, current deviation control and pulse width modulation, and acts on a DC/DC converter to control the on-off of an IGBT (insulated gate bipolar transistor), so that the output voltage of the self-synchronizing voltage source grid-connected device is stable; the method can predict the damping change between the new energy source voltage source and the power grid, timely adjusts the damping parameters in the self-synchronizing control method, enables the control method to be more flexible, can quickly recover to a normal state when the new energy source voltage generates large frequency fluctuation, and reduces the impact of the voltage and frequency fluctuation on the power grid and the micro-grid.
Fig. 4 is a schematic structural diagram of an output voltage control system 400 of a self-synchronous voltage source grid-connected device according to an embodiment of the present invention. As shown in fig. 4, an output voltage control system 400 of a self-synchronous voltage source grid-connected device according to an embodiment of the present invention includes: a grid-connected point voltage prediction unit 401, a direct current bus voltage control unit 402, a self-synchronization control unit 403, a deviation control unit 404, and an output voltage control unit 405.
Preferably, the grid-connected point voltage prediction unit 401 is configured to determine a predicted value of a next-time grid-connected point voltage according to a port voltage of a new energy voltage source, an equivalent damping of the new energy voltage source, an output power of the new energy voltage source, and an actual measured value of the grid-connected point voltage of the self-synchronous voltage source grid-connected device at a current time when an 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.
Preferably, the grid-connected point voltage predicting unit 401, determining a predicted value of the grid-connected point voltage at the next time 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-connected point voltage of the self-synchronizing voltage source grid-connected device at the current time, includes:
U2(k+1)＝Ug(k)+D(k)P(k+1)/U2(k+1)≈Ug(k)+D(k)P(k)/U2(k)，
D(k)＝(U-Ug(k))U/P(k)，
wherein, U2(k +1) is a predicted value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the next moment k + 1; u shape2(k) The measured value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the current moment k is obtained; d (k) is the equivalent damping of the new energy voltage source at the moment k; p (k) is the output power of the new energy source voltage source at the moment k; u shapeg(k) The port voltage of the new energy source voltage source at the moment k; u is the sending voltage value of the ideal new energy source voltage source.
Preferably, the dc bus voltage control unit 402 is configured to compare and track the predicted value of the grid-connected point voltage at the next time with a preset voltage reference value, control the dc bus voltage, and obtain an active power reference value of the self-synchronizing voltage source grid-connected device.
Preferably, the self-synchronization control unit 403 is configured to perform self-synchronization control according to an active power reference value of the self-synchronization 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.
Preferably, wherein the system further comprises: a computing unit to:
calculating an armature voltage of the DC generator using:
E＝U2+IRa＝CTφω，
calculating the mechanical torque of the DC generator by using the following method:
calculating the electromagnetic torque of the DC generator by the following method:
calculating the DC angular velocity of the DC generator using the following mechanical equations, including:
wherein E is the armature voltage of the direct current generator; cTIs a torque coefficient; phi is magnetic flux; omega is the mechanical angular speed of the direct current generator; u shape2Is the grid-connected point voltage; raIs an armature resistance; t iseAnd TmElectromagnetic torque and mechanical torque of the direct current generator are respectively; pmThe active power reference value of the direct current generator; h is a preset inertia coefficient; d is the equivalent damping of the new energy source voltage source; omega0Is a rated mechanical angular velocity; i isrefIs a current reference value; pe is the electromagnetic power of the DC generator.
Preferably, the deviation control unit 404 is configured 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.
Preferably, the output voltage control unit 405 is configured 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 on-time of the IGBT, so as to stabilize the output voltage of the self-synchronizing voltage source grid-connected device.
Preferably, the modulation signal comprises: the IGBT tube comprises a first modulation signal and a second modulation signal, and comprises: the IGBT device comprises a first IGBT tube and a second IGBT tube.
Preferably, the output voltage control unit further includes:
when the modulation signal is 1, controlling the IGBT tube to be conducted; and when the modulation signal is 0, controlling the IGBT tube to be disconnected.
The output voltage control system 400 of the self-synchronous voltage source grid-connected device according to the embodiment of the present invention corresponds to the output voltage control method 100 of the self-synchronous voltage source grid-connected device according to another embodiment of the present invention, and is not described herein again.
The invention has been described with reference to a few embodiments. However, other embodiments of the invention than the one disclosed above are equally possible within the scope of the invention, as would be apparent to a person skilled in the art from the appended patent claims.
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/an/the [ device, component, etc ]" are to be interpreted openly as referring to at least one instance of said device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (10)
1. An output voltage control method of a self-synchronizing voltage source grid-connected device is characterized by comprising the following steps:
when the output power fluctuation value of a new energy voltage source of the self-synchronizing voltage source grid-connected device exceeds a preset output power fluctuation threshold value, determining a predicted value of the grid-connected 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-connected point voltage of the self-synchronizing voltage source grid-connected device at the current moment;
comparing and tracking the predicted value of the grid-connected point voltage at the next moment with a preset voltage reference value, controlling the direct current bus voltage, and acquiring an active power reference value of the self-synchronizing voltage source grid-connected device;
performing self-synchronization control according to the active power reference value of the self-synchronization voltage source grid-connected device, the armature voltage of the direct current generator, the mechanical torque of the direct current generator, the electromagnetic torque of the direct current generator and the mechanical angular speed of the direct current generator to obtain a current reference value;
performing deviation control according to the current reference value and the sampling current value of the grid-connected point to obtain a control signal;
and 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) tube, so as to realize the stability of the output voltage of the self-synchronizing voltage source grid-connected device.
2. The method according to claim 1, wherein the determining a predicted value of a grid-connected point voltage at a next time 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-connected point voltage of the self-synchronous voltage source grid-connected device at the current time comprises:
U2(k+1)＝Ug(k)+D(k)P(k+1)/U2(k+1)≈Ug(k)+D(k)P(k)/U2(k)，
D(k)＝(U-Ug(k))U/P(k)，
wherein, U2(k +1) is a predicted value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the next moment k + 1; u shape2(k) The measured value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the current moment k is obtained; d (k) is the equivalent damping of the new energy voltage source at the moment k; p (k) is the output power of the new energy source voltage source at the moment k; u shapeg(k) The port voltage of the new energy source voltage source at the moment k; u is the sending voltage value of the ideal new energy source voltage source.
3. The method of claim 1, further comprising:
calculating an armature voltage of the DC generator using:
E＝U2+IRa＝CTφω，
calculating the mechanical torque of the DC generator by using the following method:
calculating the electromagnetic torque of the DC generator by the following method:
calculating the DC angular velocity of the DC generator using the following mechanical equations, including:
wherein E is the armature voltage of the direct current generator; cTIs a torque coefficient; phi is magnetic flux; omega is the mechanical angular speed of the direct current generator; u shape2Is the grid-connected point voltage; raIs an armature resistance; t iseAnd TmElectromagnetic torque and mechanical torque of the direct current generator are respectively; pmThe active power reference value of the direct current generator; h is a preset inertia coefficient; d is the equivalent damping of the new energy source voltage source; omega0Is a rated mechanical angular velocity; i isrefIs a current reference value; pe is the electromagnetic power of the DC generator.
4. The method of claim 1, wherein modulating the signal comprises: the IGBT tube comprises a first modulation signal and a second modulation signal, and comprises: the IGBT device comprises a first IGBT tube and a second IGBT tube.
5. The method of claim 1, further comprising:
when the modulation signal is 1, controlling the IGBT tube to be conducted; and when the modulation signal is 0, controlling the IGBT tube to be disconnected.
6. An output voltage control system of a self-synchronizing voltage source grid-connected device, characterized in that the system comprises:
the grid-connected point voltage prediction unit is used for determining a predicted value of the grid-connected 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-connected 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;
the direct current bus voltage control unit is used for comparing and tracking the predicted value of the grid-connected point voltage at the next moment with a preset voltage reference value, controlling the direct current bus voltage and obtaining an active power reference value of the self-synchronizing voltage source grid-connected device;
the self-synchronization control unit is used for carrying out self-synchronization control according to the active power reference value of the self-synchronization voltage source grid-connected device, the armature voltage of the direct current generator, the mechanical torque of the direct current generator, the electromagnetic torque of the direct current generator and the mechanical angular speed of the direct current generator so as to obtain a current reference value;
the deviation control unit is used for carrying out deviation control according to the current reference value and the sampling current value of the grid-connected point so as to obtain a control signal;
and the output voltage control unit is used for carrying out pulse width modulation according to the control signal so as to obtain a modulation signal, and sending the modulation signal to the DC/DC converter so as to control the conduction time of the IGBT tube and realize the stabilization of the output voltage of the self-synchronizing voltage source grid-connected device.
7. The system according to claim 6, wherein the grid-connected point voltage predicting unit determines a predicted value of the grid-connected point voltage at the next time 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-connected point voltage of the self-synchronous voltage source grid-connected device at the current time, and comprises:
U2(k+1)＝Ug(k)+D(k)P(k+1)/U2(k+1)≈Ug(k)+D(k)P(k)/U2(k)，
D(k)＝(U-Ug(k))U/P(k)，
wherein, U2(k +1) is the autonomy at the next time k +1Step voltage source grid-connected device grid-connected point voltage prediction value; u shape2(k) The measured value of the grid-connected point voltage of the self-synchronizing voltage source grid-connected device at the current moment k is obtained; d (k) is the equivalent damping of the new energy voltage source at the moment k; p (k) is the output power of the new energy source voltage source at the moment k; u shapeg(k) The port voltage of the new energy source voltage source at the moment k; u is the sending voltage value of the ideal new energy source voltage source.
8. The system of claim 6, further comprising: a computing unit to:
calculating an armature voltage of the DC generator using:
E＝U2+IRa＝CTφω，
calculating the mechanical torque of the DC generator by using the following method:
calculating the electromagnetic torque of the DC generator by the following method:
calculating the DC angular velocity of the DC generator using the following mechanical equations, including:
wherein E is the armature voltage of the direct current generator; cTIs a torque coefficient; phi is magnetic flux; omega is the mechanical angular speed of the direct current generator; u shape2Is the grid-connected point voltage; raIs an armature resistance; t iseAnd TmElectromagnetic torque and mechanical torque of the direct current generator are respectively; pmIs a direct currentAn active power reference value of the generator; h is a preset inertia coefficient; d is the equivalent damping of the new energy source voltage source; omega0Is a rated mechanical angular velocity; i isrefIs a current reference value; pe is the electromagnetic power of the DC generator.
9. The system of claim 6, wherein the modulated signal comprises: the IGBT tube comprises a first modulation signal and a second modulation signal, and comprises: the IGBT device comprises a first IGBT tube and a second IGBT tube.
10. The system of claim 6, wherein the output voltage control unit further comprises:
when the modulation signal is 1, controlling the IGBT tube to be conducted; and when the modulation signal is 0, controlling the IGBT tube to be disconnected.
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| CN113964879B (en) * | 2021-11-23 | 2022-12-02 | 合肥工业大学 | New energy grid-connected inverter self-synchronizing voltage source control method |
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