CN111725843A - Voltage control method and device based on virtual synchronous generator - Google Patents
Voltage control method and device based on virtual synchronous generator Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/40—Synchronising a generator for connection to a network or to another generator
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
- H02P9/14—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P2103/00—Controlling arrangements characterised by the type of generator
- H02P2103/20—Controlling arrangements characterised by the type of generator of the synchronous type
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Abstract
The application discloses voltage control method and device based on virtual synchronous generator, wherein the method comprises the following steps: acquiring a d-axis current instruction value output by a virtual synchronous generator; acquiring direct-current voltage of a power transmission system, and comparing the direct-current voltage with an upper limit value and a lower limit value of a preset voltage interval respectively to obtain a comparison result; calculating to obtain a first current value through a proportional-integral controller according to the comparison result; summing the first current value and the d-axis current instruction value to obtain a second current value; and adjusting the virtual synchronous generator according to the second current value to obtain a standard voltage, wherein the standard voltage is any one voltage value in a preset voltage interval, and when the voltage deviation reaches a set margin value, a certain 'desaturation' time, namely switching time is still required at present, and the direct current voltage of the system is uncontrolled at the moment, so that the voltage fluctuation is large, and the technical problem of system stability is solved.
Description
Technical Field
The application relates to the technical field of power systems, in particular to a voltage control method and device based on a virtual synchronous generator.
Background
With the increasing prominence of energy crisis and environmental problems, the distributed power generation technology receives more and more attention, and the operation characteristics of the grid-connected inverter as a link between a distributed power supply and a microgrid are widely researched. The conventional grid-connected inverter is high in influence speed, almost has no rotational inertia, is difficult to participate in power grid regulation, cannot provide necessary voltage and frequency support for an active power distribution network containing a distributed power supply, and even cannot provide necessary damping action for a micro-grid with relatively poor stability. The virtual synchronous generator technology simulates the working principle of the synchronous generator through a control strategy, so that the power electronic converter can provide inertia and damping for the system like the synchronous generator.
The existing virtual synchronous generator is combined with classical second-order voltage deviation control, the frequency stability of the system is effectively improved, but when the voltage deviation reaches a set margin value, certain 'desaturation' time, namely switching time is still needed, and the direct-current voltage of the system is uncontrolled at the moment, so that the voltage fluctuation is large, and the system stability is reduced.
Disclosure of Invention
The application provides a voltage control method and a voltage control device based on a virtual synchronous generator, which are used for solving the technical problems that the virtual synchronous generator is combined with the classical second-order voltage deviation control, when the voltage deviation reaches the set margin value, certain 'desaturation' time is still needed, namely, the switching time, and the direct current voltage of the system is uncontrolled at the moment, so that the voltage fluctuation is large, and the stability of the system is reduced.
In view of the above, a first aspect of the present application provides a virtual synchronous generator-based voltage control method, including:
acquiring a d-axis current instruction value output by a virtual synchronous generator;
acquiring direct-current voltage of a power transmission system, and comparing the direct-current voltage with an upper limit value and a lower limit value of a preset voltage interval respectively to obtain a comparison result;
calculating to obtain a first current value through a proportional-integral controller according to the comparison result;
summing the first current value and the d-axis current instruction value to obtain a second current value;
and adjusting the virtual synchronous generator according to the second current value to obtain a standard voltage, wherein the standard voltage is any one voltage value in the preset voltage interval.
Optionally, the obtaining a d-axis current command value output by the virtual synchronous generator includes:
and acquiring a three-phase current instruction value output by the virtual synchronous generator, and performing rotation coordinate transformation on the three-phase current instruction value through a preset phase angle to obtain a d-axis current instruction value.
Optionally, the comparison result is that the dc voltage is greater than an upper limit value of the preset voltage interval;
the calculating to obtain the first current value through a proportional-integral controller according to the comparison result comprises:
calculating to obtain a first current value through a first calculation formula of a proportional-integral controller according to a first difference value between the direct-current voltage and an upper limit value of the preset voltage interval;
the first calculation formula is:
wherein, Δ ihIs the first current value, udcIs said direct voltage, kpAnd kiAre parameters of the proportional-integral controller,
is a high pressure threshold.
Optionally, the comparison result is that the dc voltage is smaller than a lower limit value of the preset voltage interval;
the calculating to obtain the first current value through a proportional-integral controller according to the comparison result comprises:
calculating to obtain a first current value through a second calculation formula of a proportional-integral controller according to a second difference value between the direct-current voltage and the lower limit value of the preset voltage interval;
the second calculation formula is:
wherein, Δ ilIs the first current value, udcIs said direct voltage, kpAnd kiAre parameters of the proportional-integral controller,
is a low pressure threshold.
Optionally, the comparison result is that the dc voltage is less than or equal to an upper limit value of the preset voltage interval and greater than or equal to a lower limit value of the preset voltage interval;
the calculating to obtain the first current value through a proportional-integral controller according to the comparison result comprises:
and calculating to obtain a first current value of 0 through a proportional integral controller according to the comparison result.
The second aspect of the present application provides a voltage control apparatus based on a virtual synchronous generator, including: the device comprises a first acquisition unit, a second acquisition unit, a first calculation unit, a second calculation unit and a third calculation unit;
the first acquisition unit is used for acquiring a d-axis current instruction value output by the virtual synchronous generator;
the second obtaining unit is used for obtaining the direct-current voltage of the power transmission system and comparing the direct-current voltage with an upper limit value and a lower limit value of a preset voltage interval respectively to obtain a comparison result;
the first calculating unit is used for calculating to obtain a first current value through a proportional-integral controller according to the comparison result;
the second calculating unit is used for carrying out summation operation on the first current value and the d-axis current instruction value to obtain a second current value;
and the third calculating unit is used for adjusting the virtual synchronous generator according to the second current value to obtain a standard voltage, wherein the standard voltage is any one voltage value in the preset voltage interval.
Optionally, the first obtaining unit is specifically configured to obtain a three-phase current command value output by the virtual synchronous generator, and perform rotation coordinate transformation on the three-phase current command value through a preset phase angle to obtain a d-axis current command value.
Optionally, the comparison result is that the dc voltage is greater than an upper limit value of the preset voltage interval;
the first calculating unit is specifically configured to calculate, according to a first difference between the direct-current voltage and an upper limit value of the preset voltage interval, a first current value through a first calculation formula of a proportional-integral controller;
the first calculation formula is:
wherein, Δ ihIs the first current value, udcIs said direct voltage, kpAnd kiAre parameters of the proportional-integral controller,
is a high pressure threshold.
Optionally, the comparison result is that the dc voltage is smaller than a lower limit value of the preset voltage interval;
the first calculation unit is specifically used for calculating a first current value through a second calculation formula of a proportional-integral controller according to a second difference value between the direct-current voltage and a lower limit value of the preset voltage interval;
the second calculation formula is:
wherein, Δ ilIs the first current value, udcIs said direct voltage, kpAnd kiAre parameters of the proportional-integral controller,
is a low pressure threshold.
Optionally, the comparison result is that the dc voltage is less than or equal to an upper limit value of the preset voltage interval and greater than or equal to a lower limit value of the preset voltage interval;
the first calculating unit is specifically configured to calculate, according to the comparison result, a first current value to be 0 through a proportional-integral controller.
According to the technical scheme, the method has the following advantages:
the application discloses voltage control method based on virtual synchronous generator includes: acquiring a d-axis current instruction value output by a virtual synchronous generator; acquiring direct-current voltage of a power transmission system, and comparing the direct-current voltage with an upper limit value and a lower limit value of a preset voltage interval respectively to obtain a comparison result; calculating to obtain a first current value through a proportional-integral controller according to the comparison result; summing the first current value and the d-axis current instruction value to obtain a second current value; and regulating the virtual synchronous generator according to the second current value to obtain a standard voltage, wherein the standard voltage is any one voltage value in a preset voltage interval.
After the direct current voltage of a power transmission system is obtained, the direct current voltage is respectively compared with an upper limit value and a lower limit value of a preset voltage interval to obtain a comparison result, a first current value is obtained through calculation by a proportional-integral controller according to the corresponding comparison result, namely when the direct current voltage is not in the preset voltage interval, the d-axis current instruction value output by a virtual synchronous generator is increased or reduced through the first current value obtained through calculation immediately, so that the fluctuation of the direct current voltage is reduced, the first current value is superposed on the d-axis current instruction value to obtain a second current value, so that the standard voltage can be regulated to be obtained, the direct current voltage is stabilized in the preset voltage interval, the active current of a receiving end converter is increased or reduced to reduce the fluctuation of the direct current voltage, the active power flow balance of a transmitting end and a receiving end of the direct current system is promoted, and the stability of the system is improved, the technical problems that a virtual synchronous generator is combined with classical second-order voltage deviation control in the prior art, when the voltage deviation reaches a set margin value, certain 'desaturation' time, namely switching time is still needed, and the direct-current voltage of a system is uncontrolled at the moment, so that voltage fluctuation is large, and the stability of the system is reduced are solved.
Drawings
Fig. 1 is a schematic flowchart of a voltage control method based on a virtual synchronous generator according to an embodiment of the present application;
fig. 2 is another schematic flow chart of a virtual synchronous generator-based voltage control method according to an embodiment of the present disclosure;
FIG. 3 is a block diagram of a VSG control algorithm with DC voltage coordination control provided by an embodiment of the present application;
FIG. 4 is a block diagram of a VSG control algorithm provided in an embodiment of the present application;
fig. 5 is a schematic structural diagram of a voltage control device based on a virtual synchronous generator according to an embodiment of the present application.
Detailed Description
The embodiment of the application provides a voltage control method and a voltage control device based on a virtual synchronous generator, which are used for solving the technical problems that the virtual synchronous generator is combined with classical second-order voltage deviation control, certain 'desaturation' time is still needed when the voltage deviation reaches a set margin value, namely, switching time, and the direct current voltage of a system is uncontrolled at the moment, so that voltage fluctuation is large, and the stability of the system is reduced.
In order to make the objects, features and advantages of the present invention more apparent and understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the embodiments described below are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1 and fig. 3, an embodiment of the present application provides a voltage control method based on a virtual synchronous generator, including:
and 101, acquiring a d-axis current command value output by the virtual synchronous generator.
The d-axis current command value output by the virtual synchronous generator is directly compensated or reduced on the basis of maintaining the original control strategy of the virtual synchronous generator. Therefore, the d-axis current command value output when the virtual synchronous generator is operated is acquired.
And 102, acquiring direct current voltage of the power transmission system, and comparing the direct current voltage with an upper limit value and a lower limit value of a preset voltage interval respectively to obtain a comparison result.
It should be noted that if
And
set too close to the steady-state value u of the DC voltagedc_refMay cause the control of the virtual synchronous generator to produce unnecessary actions within the normal voltage fluctuation range of the system. If it is
And
too far from the steady-state value u of the DC voltagedc_refThe system can be caused to have problems of overvoltage or continuous undervoltage and the like under the condition of power unbalance. In order to avoid unnecessary actions, maintain the dc voltage of the system within a reasonable range under the condition of power imbalance, and enable the converters to participate in power coordination together when the power is unbalanced, the upper limit value of the preset voltage interval in the embodiment is set as
The lower limit value is set as
Wherein,
is a high voltage threshold, udc_refIs a steady-state value of the direct current voltage, is a preset voltage threshold value,
is a low pressure threshold.
It can be understood that when the injection power of the transmitting end of the dc transmission system is greater than the output power of the receiving end, the dc voltage will shift upwards, and when the injection power of the transmitting end of the dc transmission system is less than the output power of the receiving end, the dc voltage will shift downwards, so that the dc voltage u is converted into the dc voltage udcComparing with the upper limit value and the lower limit value of the preset voltage interval respectively to obtain different comparison results, wherein the DC voltage u may appeardcExceeding a high pressure threshold
A DC voltage u may also occurdcLess than the low-pressure threshold
A DC voltage u may also occurdcIn a preset voltage interval, i.e. DC voltage udcLess than the high pressure threshold
Greater than a low pressure threshold
And 103, calculating to obtain a first current value through a proportional integral controller according to the comparison result.
According to different comparison results, the first current value can be calculated by a corresponding proportional-integral controller, and of course, the first current value can be a positive number, a negative number or 0.
And 104, carrying out summation operation on the first current value and the d-axis current instruction value to obtain a second current value.
And summing the first current value and the d-axis current command value, wherein the d-axis current command value is compensated when the first current value is a positive number, and the d-axis current command value is reduced when the first current value is a negative number.
And 105, regulating the virtual synchronous generator according to the second current value to obtain a standard voltage.
A second current value is obtained by summing the first current value and the d-axis current instruction value to increase or decrease the output of the active current of the current converter at the receiving end, namely the d-axis current instruction value, so that the active power flow of the transmitting end and the receiving end of the direct current system are balanced, a standard voltage is obtained by adjusting according to the second current value, the standard voltage is an adjusted direct current voltage, the adjusted direct current voltage is any voltage value in a preset voltage interval, and the direct current voltage u can be controlleddcAnd stabilizing in a preset voltage interval.
After the direct current voltage of a power transmission system is obtained, the direct current voltage is compared with an upper limit value and a lower limit value of a preset voltage interval respectively to obtain a comparison result, a first current value is obtained through calculation by a proportional-integral controller according to the corresponding comparison result, namely when the direct current voltage is not in the preset voltage interval, the d-axis current instruction value output by a virtual synchronous generator is increased or reduced through the first current value obtained through calculation immediately, so that the fluctuation of the direct current voltage is reduced, the first current value is superposed on the d-axis current instruction value to obtain a second current value, so that the standard voltage can be obtained through regulation, the direct current voltage is stabilized in the preset voltage interval, the active current of a current converter at a receiving end is increased or reduced to reduce the fluctuation of the direct current voltage, the active power flow balance of a transmitting end and a receiving end of the direct current system is promoted, and the stability of the system is improved, the technical problems that a virtual synchronous generator is combined with classical second-order voltage deviation control in the prior art, when the voltage deviation reaches a set margin value, certain 'desaturation' time, namely switching time is still needed, and the direct-current voltage of a system is uncontrolled at the moment, so that voltage fluctuation is large, and the stability of the system is reduced are solved.
The above is a detailed description of a first embodiment of a virtual synchronous generator-based voltage control method provided by the present application, and the following is a detailed description of a second embodiment of a virtual synchronous generator-based voltage control method provided by the present application.
Referring to fig. 2, 3 and 4, an embodiment of the present application provides a voltage control method based on a virtual synchronous generator, including:
In the second-order model of the synchronous motor in the embodiment, which considers the rotor inertia and the damping factor, the mechanical equation and the electromagnetic equation can be respectively expressed as:
wherein J is the rotational inertia of the virtual synchronous generator, and omega is the mechanical angular velocity with the polar pair number of 1 hour, namely the electrical angular velocity, omegaNFor nominal angular velocity, theta is the angular displacement of the rotor, i.e. the preset phase angle, PmAnd PeMechanical and electromagnetic power, respectively, of a virtual synchronous generator, DpIs the damping coefficient of the virtual synchronous generator.
While providing inertia and damping to the power transmission system,the active regulation response can be made according to the deviation of the frequency of the access point to actively participate in the frequency modulation of the power grid, and the mechanical power P of the active regulation responsemComprises the following steps:
Pm＝Pref+kf(f0-f)；
wherein, PrefFor a given active power, kfIs the frequency modulation coefficient, f0Is the nominal frequency and f is the actual frequency.
According to mechanical power PmAnd calculating a preset phase angle, namely the phase angle theta of the virtual synchronous generator:
wherein J is the moment of inertia of the virtual synchronous generator, PeElectromagnetic power, omega, for a virtual synchronous generatorNAt nominal angular velocity, s is the Laplace operator, DpIs the damping coefficient.
As shown in fig. 4, the reference voltage and the measured virtual synchronous generator terminal voltage U are connected to a PI controller, and the potential amplitude E of the virtual synchronous generator is obtained:
wherein E is0Is the effective value of no-load electromotive force, k, of the virtual synchronous generatorqTo adjust the coefficient of reactive power, QrefAnd Q is the reactive instruction and reactive output value of the virtual synchronous generator, Ke_pIs the proportionality coefficient of the PI controller, Ke_iS is the laplacian operator, which is the integral coefficient of the PI controller.
Combining reference potentials E and theta into a three-phase reference voltage
From three-phase reference voltages of virtual synchronous generators
And terminal voltage uabcAnd calculating to obtain three-phase current command value of the virtual synchronous generator
Wherein,
is a three-phase reference voltage, uabcL and R are the terminal voltage, respectively the virtual synchronous reactance and resistance of the virtual synchronous generator, and s is the laplace operator.
It should be noted that, in this embodiment, the three-phase current command value output by the virtual synchronous generator is obtained first, and then the three-phase current command value is obtained
And carrying out rotation coordinate transformation according to a preset phase angle theta to obtain d-axis and q-axis current instruction values.
And step 203, calculating to obtain a first current value through a proportional integral controller according to the comparison result.
As shown in fig. 3, it should be noted that, when the power transmission system is operating normally, the main converter station in the constant dc voltage control mode is used as a balance node to balance the power fluctuation of the system, so as to maintain the stable operation of the multi-terminal dc system. DC voltage udcAt high pressure threshold
And low voltage threshold
And if the comparison result shows that the direct-current voltage is less than or equal to the upper limit value of the preset voltage interval and greater than or equal to the lower limit value of the preset voltage interval, calculating to obtain a first current value of 0 through the proportional-integral controller according to the comparison result.
It can be understood that when the injection power of the sending end of the system is larger than the output power of the receiving end, the direct current voltage udcIs shifted upwards when the DC voltage u is applieddcExceeding a high pressure threshold ud*c_hWhen the proportional-integral controller, i.e. the high-voltage controller, outputs a positive first current value Δ ihThereby increasing the absolute value of the d-axis current command value. That is to say, when the comparison result is that the dc voltage is greater than the upper limit value of the preset voltage interval, according to a first difference value between the dc voltage and the upper limit value of the preset voltage interval, a first current value is calculated by a first calculation formula of the proportional-integral controller, and the active current output of the current converter at the receiving end is increased to promote the active power flow balance at the transmitting end and the receiving end of the dc system, so as to finally control the dc voltage to be stabilized at the preset voltage interval.
The first calculation formula is:
wherein, Δ ihIs a first current value, udcIs a DC voltage, kpAnd kiAre parameters of the proportional-integral controller,
is a high pressure threshold.
When the system is sent to the end to inject workWhen the rate is less than the output power of the receiving end, the direct current voltage udcIs shifted downwards when the DC voltage u isdcBelow the low pressure threshold
When the proportional-integral controller, i.e. the low-voltage controller, outputs a negative first current value Δ ilThat is, when the comparison result is the DC voltage udcIs less than the lower limit value of the preset voltage interval; according to a second difference value between the direct current voltage and the lower limit value of the preset voltage interval, a first current value is obtained through calculation of a second calculation formula of the proportional-integral controller, so that the absolute value of the d-axis current instruction value is reduced, the active current output of the current receiving end converter is reduced, and the direct current voltage u is preventeddcFurther falling. Similarly, after the first current value calculated by the proportional-integral controller is obtained, the first current value is compared with 0, if the first current value is smaller than 0, the first current value can be directly output, and if the first current value is not smaller than 0, the output value is 0.
The second calculation formula is:
wherein, Δ ilIs a first current value, udcIs a DC voltage, kpAnd kiAre parameters of the proportional-integral controller,
is a low pressure threshold.
And 204, carrying out summation operation on the first current value and the d-axis current instruction value to obtain a second current value.
And step 205, adjusting the virtual synchronous generator according to the second current value to obtain a standard voltage.
It should be noted that the standard voltage is an adjusted dc voltage, and the adjusted dc voltage is located in a preset voltage interval, so that the dc voltage u can be controlleddcAnd stabilizing in a preset voltage interval.
In the embodiment, after the direct-current voltage of a power transmission system is obtained, the direct-current voltage is respectively compared with an upper limit value and a lower limit value of a preset voltage interval to obtain a comparison result, a first current value is obtained through calculation by a proportional-integral controller according to the corresponding comparison result, namely when the direct-current voltage is not in the preset voltage interval, the d-axis current instruction value output by a virtual synchronous generator is increased or reduced through the first current value obtained through calculation, so that the fluctuation of the direct-current voltage is reduced, the first current value is superposed to the d-axis current instruction value to obtain a second current value, so that the standard voltage can be adjusted to be obtained, the direct-current voltage is stabilized in the preset voltage interval, the active current of a converter at a receiving end is increased or reduced to reduce the fluctuation of the direct-current voltage, the active power flow balance of a transmitting end and a receiving end of the direct-current system is promoted, and, the technical problems that a virtual synchronous generator is combined with classical second-order voltage deviation control in the prior art, when the voltage deviation reaches a set margin value, certain 'desaturation' time, namely switching time is still needed, and the direct-current voltage of a system is uncontrolled at the moment, so that voltage fluctuation is large, and the stability of the system is reduced are solved.
The above is a detailed description of a second embodiment of the virtual synchronous generator-based voltage control method provided by the present application, and the following is a detailed description of an embodiment of the virtual synchronous generator-based voltage control device provided by the present application.
Referring to fig. 5, an embodiment of the present application provides a voltage control apparatus based on a virtual synchronous generator, including: a first acquisition unit 501, a second acquisition unit 502, a first calculation unit 503, a second calculation unit 504, and a third calculation unit 505;
a first obtaining unit 501, configured to obtain a d-axis current command value output by the virtual synchronous generator.
A second obtaining unit 502, configured to obtain a dc voltage of the power transmission system, and compare the dc voltage with an upper limit value and a lower limit value of the preset voltage interval, respectively, to obtain a comparison result.
The first calculating unit 503 is configured to calculate a first current value through a proportional-integral controller according to the comparison result.
The second calculating unit 504 is configured to perform summation operation on the first current value and the d-axis current command value to obtain a second current value.
And a third calculating unit 505, configured to adjust the virtual synchronous generator according to the second current value to obtain a standard voltage, where the standard voltage is any one voltage value in a preset voltage interval.
Further, the first obtaining unit 501 is specifically configured to obtain three-phase current command values output by the virtual synchronous generator, and perform rotation coordinate transformation on the three-phase current command values through a preset phase angle to obtain a d-axis current command value.
Further, when the comparison result is that the dc voltage is greater than the upper limit value of the preset voltage interval, the first calculating unit 503 is specifically configured to calculate, according to a first difference between the dc voltage and the upper limit value of the preset voltage interval, a first current value by using a first calculation formula of the proportional-integral controller;
the first calculation formula is:
wherein, Δ ihIs a first current value, udcIs a DC voltage, kpAnd kiAre parameters of the proportional-integral controller,
is a high pressure threshold.
Further, when the comparison result is that the dc voltage is smaller than the lower limit value of the preset voltage interval, the first calculating unit 503 is specifically configured to calculate, according to a second difference between the dc voltage and the lower limit value of the preset voltage interval, a first current value by using a second calculation formula of the proportional-integral controller;
the second calculation formula is:
wherein, Δ ilIs a first current value, udcIs a DC voltage, kpAnd kiAre parameters of the proportional-integral controller,
is a low pressure threshold.
Further, when the comparison result is that the dc voltage is less than or equal to the upper limit value of the preset voltage interval and greater than or equal to the lower limit value of the preset voltage interval, the first calculating unit 503 is specifically configured to calculate the obtained first current value to be 0 through a proportional-integral controller according to the comparison result.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the network, the apparatus and the unit described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described device embodiments are merely illustrative, and for example, the division of the units is only one logical functional division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another grid network to be installed, or some features may be omitted or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-only memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (10)
1. A voltage control method based on a virtual synchronous generator is characterized by comprising the following steps:
acquiring a d-axis current instruction value output by a virtual synchronous generator;
acquiring direct-current voltage of a power transmission system, and comparing the direct-current voltage with an upper limit value and a lower limit value of a preset voltage interval respectively to obtain a comparison result;
calculating to obtain a first current value through a proportional-integral controller according to the comparison result;
summing the first current value and the d-axis current instruction value to obtain a second current value;
and adjusting the virtual synchronous generator according to the second current value to obtain a standard voltage, wherein the standard voltage is any one voltage value in the preset voltage interval.
2. The virtual synchronous generator-based voltage control method according to claim 1, wherein the obtaining of the d-axis current command value output by the virtual synchronous generator comprises:
and acquiring a three-phase current instruction value output by the virtual synchronous generator, and performing rotation coordinate transformation on the three-phase current instruction value through a preset phase angle to obtain a d-axis current instruction value.
3. The virtual synchronous generator-based voltage control method according to claim 1, wherein the comparison result is that the dc voltage is greater than an upper limit value of the preset voltage interval;
the calculating to obtain the first current value through a proportional-integral controller according to the comparison result comprises:
calculating to obtain a first current value through a first calculation formula of a proportional-integral controller according to a first difference value between the direct-current voltage and an upper limit value of the preset voltage interval;
the first calculation formula is:
wherein, Δ ihIs the first current value, udcIs said direct voltage, kpAnd kiAre parameters of the proportional-integral controller,
is a high pressure threshold.
4. The virtual synchronous generator-based voltage control method according to claim 1, wherein the comparison result is that the direct-current voltage is smaller than a lower limit value of the preset voltage interval;
the calculating to obtain the first current value through a proportional-integral controller according to the comparison result comprises:
calculating to obtain a first current value through a second calculation formula of a proportional-integral controller according to a second difference value between the direct-current voltage and the lower limit value of the preset voltage interval;
the second calculation formula is:
wherein, Δ ilIs the first current value, udcIs said direct voltage, kpAnd kiAre parameters of the proportional-integral controller,
is a low pressure threshold.
5. The virtual synchronous generator-based voltage control method according to claim 1, wherein the comparison result is that the dc voltage is less than or equal to an upper limit value of the preset voltage interval and greater than or equal to a lower limit value of the preset voltage interval;
the calculating to obtain the first current value through a proportional-integral controller according to the comparison result comprises:
and calculating to obtain a first current value of 0 through a proportional integral controller according to the comparison result.
6. A virtual synchronous generator-based voltage control apparatus, comprising: the device comprises a first acquisition unit, a second acquisition unit, a first calculation unit, a second calculation unit and a third calculation unit;
the first acquisition unit is used for acquiring a d-axis current instruction value output by the virtual synchronous generator;
the second obtaining unit is used for obtaining the direct-current voltage of the power transmission system and comparing the direct-current voltage with an upper limit value and a lower limit value of a preset voltage interval respectively to obtain a comparison result;
the first calculating unit is used for calculating to obtain a first current value through a proportional-integral controller according to the comparison result;
the second calculating unit is used for carrying out summation operation on the first current value and the d-axis current instruction value to obtain a second current value;
and the third calculating unit is used for adjusting the virtual synchronous generator according to the second current value to obtain a standard voltage, wherein the standard voltage is any one voltage value in the preset voltage interval.
7. The voltage control device based on the virtual synchronous generator as claimed in claim 6, wherein the first obtaining unit is specifically configured to obtain three-phase current command values output by the virtual synchronous generator, and perform rotation coordinate transformation on the three-phase current command values through a preset phase angle to obtain d-axis current command values.
8. The virtual synchronous generator-based voltage control device according to claim 6, wherein the comparison result is that the DC voltage is greater than an upper limit value of the preset voltage interval;
the first calculating unit is specifically configured to calculate, according to a first difference between the direct-current voltage and an upper limit value of the preset voltage interval, a first current value through a first calculation formula of a proportional-integral controller;
the first calculation formula is:
wherein, Δ ihIs the first current value, udcIs said direct voltage, kpAnd kiAre parameters of the proportional-integral controller,
is a high pressure threshold.
9. The virtual synchronous generator-based voltage control device according to claim 6, wherein the comparison result is that the direct-current voltage is smaller than a lower limit value of the preset voltage interval;
the first calculation unit is specifically used for calculating a first current value through a second calculation formula of a proportional-integral controller according to a second difference value between the direct-current voltage and a lower limit value of the preset voltage interval;
the second calculation formula is:
wherein, Δ ilIs the first current value, udcIs said direct voltage, kpAnd kiAre parameters of the proportional-integral controller,
is a low pressure threshold.
10. The virtual synchronous generator-based voltage control device according to claim 6, wherein the comparison result is that the dc voltage is equal to or less than an upper limit value of the preset voltage interval and equal to or greater than a lower limit value of the preset voltage interval;
the first calculating unit is specifically configured to calculate, according to the comparison result, a first current value to be 0 through a proportional-integral controller.
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