CN107612046B - Single-phase converter control method and device - Google Patents
Single-phase converter control method and device Download PDFInfo
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Abstract
The invention discloses a single-phase converter control method and a device thereof, which are used for obtaining an active current calibration parameter K according to the angular speed of the grid side voltage of the current control perioddWith reactive current calibration parameter KqIn combination with Kd、KqCalibrating the active current and the reactive current, and combining the grid-side active current reference value and the grid-side reactive current reference value to obtain the active current deviation delta idDeviation from reactive current Δ iqAccording to Δ id、ΔiqTo obtain an output voltage uab(k) And are paired with uab(k) And carrying out pulse width modulation to obtain driving pulses of each switching tube in the single-phase converter, and adjusting parameters of the power grid side by controlling the on-off of the switching tubes. The invention calibrates the active current and the reactive current through the voltage angular velocity of the power grid side, namely, adjusts the active power and the reactive power through the voltage frequency of the power grid side, so that the distribution of the active power and the reactive power under the condition of voltage frequency change can meet the requirement of a power system, and the accuracy and the stability of the adjustment of the active power and the reactive power in the power system are improved.
Description
Technical Field
The invention relates to the field of new energy grid-connected power generation systems, in particular to a single-phase converter control method and a single-phase converter control device.
Background
With the continuous deterioration of the global warming problem, the development of clean energy becomes one of the hot problems concerned by the society at present, and the development and application of new energy such as photovoltaic power generation, wind power generation and the like serving as common clean energy become important ways for sustainable development in China.
In recent years, the amount of power generation from power generation systems such as photovoltaic power generation and wind power generation in power grids has been increasing. However, since the new energy depends on natural factors such as sunlight and wind power, the new energy power has time-varying characteristics and uncertainty, and the new energy power generation system has a great difference from the conventional power generation system, so that the power system incorporating the new energy power generation system may face more unstable factors such as frequency variation, voltage dip, power quality dip, and the like. The frequency variation can cause instability of active power and reactive power, and the instability of the reactive power can cause instability of voltage at the side of a power grid due to the fact that the reactive power in the power generation system is used for improving line voltage, and further the quality of electric energy is reduced. Therefore, the grid-connected power generation converter can adapt to frequency change and accurately adjust active power and reactive power, so that the active power and the reactive power can meet the requirements of a power system and assist the frequency of a power grid to recover stably.
From the working principle of the single-phase converter, the control targets of the single-phase converter are two: firstly, the voltage of a direct current side is kept constant; and secondly, the current on the side of the power grid is sinusoidal, and the accurate adjustment of the active current and the reactive current can be realized. In practical applications, technicians generally expect that a single-phase converter system can provide accurate active current and reactive current for a power grid when the frequency of a grid-connected point changes suddenly so as to ensure the stability of the frequency of the power grid. However, in the case of unstable frequency, the single-phase converter in the prior art has low accuracy in adjusting the active power and the reactive power, so that the voltage frequency on the grid side is unstable.
Therefore, how to provide a single-phase converter control method and device with high accuracy and good stability is a problem that needs to be solved by those skilled in the art at present.
Disclosure of Invention
The invention aims to provide a single-phase converter control method and a single-phase converter control device with high accuracy and good stability, which can accurately adjust active current and reactive current under the condition of unstable frequency, thereby ensuring the stability of voltage frequency at the side of a power grid.
In order to solve the above technical problem, the present invention provides a method for controlling a single-phase converter, including:
collecting the current i of the power grid side in the current control periods(k) Grid side voltage vs(k) And a DC side voltage vdc(k) And save said is(k)；
Will i iss(k) Grid n control cycles before the stored current control cycleSide current is(k-n) are α shaft currents i 'respectively in the stationary coordinate axes'α(k) And β shaft current i'β(k)；
For v is to vs(k) Carrying out angle analysis to obtain a phase angle theta (k) and an angular speed omega (k) of the power grid side voltage in the current control period;
obtaining an error phase between the phase difference of the α -axis current and the β -axis current in an ideal situation and the phase difference in an actual situation according to the omega (k)
According to the above
The theta (K) obtains an active current calibration parameter KdWith reactive current calibration parameter Kq；
To the i'α(k) And i 'to'β(k) Performing coordinate axis conversion to obtain active current i 'in a rotating coordinate system'd(k) And reactive current i'q(k)；
By said KdK toqTo the i'd(k) I 'to'q(k) Calibrating to obtain a calibrated active current id(k) And calibrating the reactive current iq(k)；
According to said vdc(k) Obtaining an active current reference value i of the power grid sided-ref(k)；
Calculating the id(k) And said id-ref(k) To obtain an active current deviation Δ idCalculating said iq(k) And a preset power grid side reactive current reference value iq-ref(k) To obtain a reactive current deviation delta iq；
According to said Δ idAnd said Δ iqObtaining an output voltage active component u'd(k) And output voltage reactive component u'q(k)；
To the u'd(k) And u's'q(k) Performing coordinate axis conversion to obtain output voltage uab(k)；
For the output voltage uab(k) And carrying out pulse width modulation to obtain driving pulses of each switching tube in the single-phase converter, and adjusting parameters of a power grid side by controlling the on-off of the switching tubes.
Preferably, the error phase between the phase difference in the ideal case and the phase difference in the actual case between the α axis and the β axis currents is obtained through the ω (k)
The specific process comprises the following steps:
substituting the omega (k) into a preset first relational expression to obtain the
Wherein the preset first relation is as follows:
Preferably, said passing through
The theta (K) obtains an active current calibration parameter KdWith reactive current calibration parameter KqThe specific process comprises the following steps:
will be described in
Substituting the theta (K) into a preset second relational expression to obtain the KdAnd said Kq(ii) a Wherein the preset second relation is as follows:
preferably, said passing through said KdK toqTo the i'd(k) I 'to'q(k) Calibrating to obtain a calibrated active current id(k) And calibrating the reactive current iq(k) The specific process comprises the following steps:
the K is addeddK toqI 'to'd(k) I 'to'q(k) Substituting into a preset third relation to obtain the id(k) And said iq(k) (ii) a Wherein the preset third relation is as follows:
id(k)＝Kd×i'd(k)
iq(k)＝i'q(k)+Kq×id(k)。
preferably, the pass pair is u'd(k) And u's'q(k) Performing coordinate axis conversion to obtain output voltage uab(k) The specific process comprises the following steps:
u 'to the ω (k)'d(k) And u's'q(k) Calibrating to obtain the calibration value u of the active component of the output voltaged(k) And output voltage reactive component calibration value uq(k)；
For the ud(k) And said uq(k) Performing coordinate axis conversion to obtain an output voltage α axis component uα(k)；
For the uα(k) Performing coordinate axis conversion to obtain the output voltage uab(k)。
Preferably, said u 'is paired according to said ω (k)'d(k) And u's'q(k) Calibrating to obtain the calibration value u of the active component of the output voltaged(k) And output voltage reactive component calibration value uq(k) The specific process comprises the following steps:
mixing the ω (k), the u'd(k) U's'q(k) Substituting a preset fourth relational expression to obtain the ud(k) And said uq(k) (ii) a Wherein the preset fourth relation is as follows:
ud＝u'd(k)+ω(k)×Ls×iq(k)
uq＝u'q(k)-ω(k)×Ls×id(k) wherein, LsRepresenting the equivalent inductance of the single-phase converter grid side.
Preferably, said pair of said ud(k) And said uq(k) Performing coordinate axis conversion to obtain an output voltage α axis component uα(k) The specific process comprises the following steps:
subjecting said u tod(k) And said uq(k) Substituting a preset fifth relational expression to obtain the uα(k) (ii) a Wherein the preset fifth relational expression is as follows:
uα(k)＝cos(θ(k))×ud(k)-sin(θ(k))×uq(k)。
preferably, said pair of said uα(k) Performing coordinate axis conversion to obtain the output voltage uab(k) The specific process comprises the following steps:
subjecting said u toα(k) Substituting a preset sixth relational expression to obtain the uab(k) (ii) a Wherein the preset sixth relational expression is as follows:
uab(k)＝uα(k)-vs(k)。
preferably, said passing through said vdc(k) Obtaining an active current reference value i of the power grid sided-ref(k) The specific process comprises the following steps:
calculating said vdc(k) And a preset DC side voltage reference value vdc-refTo obtain the outer ring deviation e of the DC side voltagedc(k)；
E is matched by PI digital controllerdc(k) Adjusting to obtain an active current reference value i of the power grid sided-ref(k)。
In order to solve the above technical problem, the present invention further provides a single-phase converter control apparatus, including:
a data acquisition and storage module for acquiring the current i of the power grid side in the current control periods(k) Grid side voltage vs(k) And a DC side voltage vdc(k) And save said is(k)；
A stationary coordinate axis assignment module for assigning the is(k) N control cycles before the stored current control cycleGrid side current i of phases(k-n) are α shaft currents i 'respectively in the stationary coordinate axes'α(k) And β shaft current i'β(k)；
A voltage angle analysis module for analyzing vs(k) Carrying out angle analysis to obtain a phase angle theta (k) and an angular speed omega (k) of the power grid side voltage in the current control period;
an error phase calculation module for obtaining an error phase between the phase difference of the ideal situation and the phase difference of the actual situation between the α axis and the β axis currents through the omega (k)
A calibration parameter calculation module for passing said
The theta (K) obtains an active current calibration parameter KdWith reactive current calibration parameter Kq；
A current coordinate shaft conversion module for converting i'α(k) And i 'to'β(k) Performing coordinate axis conversion to obtain active current i 'in a rotating coordinate system'd(k) And reactive current i'q(k)；
A current calibration module for passing the KdK toqTo the i'd(k) I 'to'q(k) Calibrating to obtain a calibrated active current id(k) And calibrating the reactive current iq(k)；
A reference active current calculation module for passing the vdc(k) Obtaining an active current reference value i of the power grid sided-ref(k)；
A current deviation calculation module for calculating the id(k) And said id-ref(k) To obtain an active current deviation Δ idCalculating said iq(k) And a preset power grid side reactive current reference value iq-ref(k) To obtain a reactive current deviation delta iq；
A current-to-voltage conversion module for passing the Δ idAnd the placeΔ i described aboveqObtaining an output voltage active component u'd(k) And output voltage reactive component u'q(k)；
A voltage coordinate shaft conversion module for converting u'd(k) And u's'q(k) Performing coordinate axis conversion to obtain output voltage uab(k)；
A drive pulse modulation module for modulating the output voltage uab(k) And carrying out pulse width modulation to obtain driving pulses of each switching tube in the single-phase converter, and adjusting parameters of a power grid side by controlling the on-off of the switching tubes.
The invention provides a single-phase converter control method, which comprises the steps of obtaining an active current calibration parameter and a reactive current calibration parameter according to the angular speed of the grid side voltage of the current control period, and calibrating the active current and the reactive current according to the two parameters. Because the angular velocity of the voltage is in direct proportion to the frequency of the voltage, in the method provided by the invention, the active current and the reactive power are calibrated according to the angular velocity of the voltage, which is equivalent to calibrating the active current and the reactive current according to the frequency of the voltage; in addition, the active current is in direct proportion to the active power, the reactive current is in direct proportion to the reactive power, and the direct proportion relation between the angular speed and the frequency is combined. The method provided by the invention can calibrate the active power and the reactive power of the power grid side according to the voltage frequency of the power grid side, so that the converter can calibrate the active power and the reactive power of the power grid side when the voltage frequency of the power grid side changes, the distribution of the active power and the reactive power can meet the requirements of a power system, and further the voltage frequency of the power grid side is more stable, so that the accuracy of the regulation of the active power and the reactive power in the power system and the stability of the voltage frequency are improved, and the accuracy of the regulation of the active power and the reactive power ensures that the voltage frequency of the power grid side is more stable and the condition of sudden voltage drop of the power grid side does not occur, so that the quality of electric energy of the power grid side is improved. The invention also provides a single-phase converter control device, which has the same technical effects and is not described herein again.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed in the prior art and the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a flowchart of a control method for a single-phase converter according to the present invention;
FIG. 2 is a circuit diagram of a single-phase converter control method according to an embodiment of the present invention;
FIG. 3 is a flow chart of a method for controlling a single-phase converter according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a single-phase converter control device provided by the invention.
Detailed Description
The core of the invention is to provide a single-phase converter control method and a device thereof with high accuracy and good stability, which can accurately adjust active current and reactive current under the condition of unstable frequency, thereby ensuring the stability of voltage frequency at the side of a power grid.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. 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 invention.
Fig. 1 shows a flowchart of a control method for a single-phase converter according to the present invention, which specifically includes:
step s 1: collecting the current i of the power grid side in the current control periods(k) Grid side voltage vs(k) And a DC side voltage vdc(k) And save is(k)；
Step s 2: will is(k) The stored power grid side current i n control periods before the current control periods(k-n) are α shaft currents i 'respectively in the stationary coordinate axes'α(k) And β shaft current i'β(k)；
Wherein n can be obtained by comparing the period of the grid-side voltage with the control period, for example: n is T/(4T)s) Wherein T represents the rated period of the voltage on the power grid side, TsRepresents a control period; the value of n can also be preset directly, and the setting mode of n does not influence the realization of the invention.
Step s 3: for vs(k) Carrying out angle analysis to obtain a phase angle theta (k) and an angular speed omega (k) of the power grid side voltage in the current control period;
specifically, a second-order generalized integrator phase-locked loop algorithm can be adopted for vs(k) Carrying out analysis; of course, other algorithms may be used for the analysis, which do not affect the implementation of the present invention.
Step s4, obtaining the error phase between the ideal phase difference and the actual phase difference between the α axis current and the β axis current according to omega (k)
It should be noted that those skilled in the art generally consider the phase difference between the α axis and β axis currents to be 90 degrees in the ideal case.
Step s 5: according to
Theta (K) obtaining an active current calibration parameter KdWith reactive current calibration parameter Kq；
Step s 6: to i'α(k) And i'β(k) Performing coordinate axis conversion to obtain active current i 'in a rotating coordinate system'd(k) And reactive current i'q(k)；
Specifically, i 'can be represented by the following relational expression'α(k) And i'β(k) And (3) carrying out coordinate axis conversion:
i'd(k)＝cos(θ(k))×i'α(k)+sin(θ(k))×i'β(k)
i'q(k)＝-sin(θ(k))×i'α(k)+cos(θ(k))×i'β(k)，
of course, other relations may be used to convert the current coordinate axes, which does not affect the implementation of the present invention.
Step s 7: by Kd、KqTo i'd(k)、i'q(k) Calibrating to obtain a calibrated active current id(k) And calibrating the reactive current iq(k)；
Step s 8: according to vdc(k) Obtaining an active current reference value i of the power grid sided-ref(k)；
Step s 9: calculate id(k) And id-ref(k) To obtain an active current deviation Δ idCalculate iq(k) And a preset power grid side reactive current reference value iq-ref(k) To obtain a reactive current deviation delta iq；
Wherein, the above iq-ref(k) The reactive current reference value required by the supporting power grid can be directly set to 0, or can be obtained from a central dispatching center of a power supply office through a remote communication means.
Step s 10: according to Δ idAnd Δ iqObtaining an output voltage active component u'd(k) And output voltage reactive component u'q(k)；
More specifically, in one embodiment, Δ i may be paired by a PI digital controllerdAnd Δ iqAre respectively calculated to obtain u'd(k) And u'q(k)。
Step s 11: to u'd(k) And u'q(k) Performing coordinate axis conversion to obtain output voltage uab(k)；
Step s 12: for output voltage uab(k) IntoAnd modulating the line pulse width to obtain the driving pulse of each switching tube in the single-phase converter, and adjusting the parameters of the power grid side by controlling the on-off of the switching tubes.
In particular implementation, u can be pairedab(k) The drive pulse is obtained by sinusoidal pulse width modulation.
It should be noted that the sequence between step s2 and step s3 may be exchanged or performed simultaneously, and the order of the two steps does not affect the implementation of the present invention. Likewise, the sequence between steps s4-s5 and step s6 does not affect the implementation of the present invention.
In a specific implementation manner provided by the invention, in step s4, an error phase between the phase difference in the ideal case and the phase difference in the actual case between the α axis and β axis currents is obtained through ω (k)
The specific process comprises the following steps:
substituting omega (k) into a preset first relational expression to obtain
Wherein, the preset first relational expression is as follows:
In the above-described implementation mode of the invention,
the first relational expression is preset, and in other implementation manners of the invention, the first relational expression can be obtained through other relational expressions, which does not influence the implementation of the invention.
In one embodiment, in step s5, the method comprises
Theta (K) obtaining an active current calibration parameter KdWith reactive current calibration parameter KqThe specific process comprises the following steps:
will be provided with
Substituting theta (K) into a preset second relational expression to obtain KdAnd Kq(ii) a Wherein, the preset second relational expression is as follows:
in one specific implementation of the invention, the pass K in step s7d、KqTo i'd(k)、i'q(k) Calibrating to obtain a calibrated active current id(k) And calibrating the reactive current iq(k) The specific process comprises the following steps:
will Kd、Kq、i'd(k)、i'q(k) Substituting into a preset third relation to obtain id(k) And iq(k) (ii) a Wherein, the preset third relational expression is as follows:
id(k)＝Kd×i'd(k)
iq(k)＝i'q(k)+Kq×id(k)。
it should be noted that in the above specific implementation, the preset third relation is adopted to couple the active current i'd(k) And reactive current i'q(k) In other embodiments, the active current and the reactive current may be calibrated in other manners, and the calibration is not limited to the above calibration manner.
In a specific embodiment provided by the present invention, the pass pair u 'in step s 11'd(k) And u'q(k) Performing coordinate axis conversion to obtain output voltage uab(k) The specific process comprises the following steps:
step s 111: from ω (k) to u'd(k) And u'q(k) Calibrating to obtain the calibration value u of the active component of the output voltaged(k) With reactive component of output voltageCalibration value uq(k)；
Step s 112: for u is pairedd(k) And uq(k) Performing coordinate axis conversion to obtain an output voltage α axis component uα(k)；
Step s 113: for u is pairedα(k) Performing coordinate axis conversion to obtain output voltage uab(k)。
Further, in step s111, u 'is paired according to ω (k)'d(k) And u'q(k) Calibrating to obtain the calibration value u of the active component of the output voltaged(k) And output voltage reactive component calibration value uq(k) The specific process comprises the following steps:
mixing omega (k), u'd(k)、u'q(k) Substituting into a preset fourth relational expression to obtain ud(k) And uq(k) (ii) a Wherein, the preset fourth relational expression is as follows:
ud＝u'd(k)+ω(k)×Ls×iq(k)
uq＝u'q(k)-ω(k)×Ls×id(k) wherein, LsRepresenting the equivalent inductance on the grid side of the single-phase converter.
In the above embodiment, further, in step s112, u is processedd(k) And uq(k) Performing coordinate axis conversion to obtain an output voltage α axis component uα(k) The specific process comprises the following steps:
will ud(k) And uq(k) Substituting into a preset fifth relational expression to obtain uα(k) (ii) a Wherein, the preset fifth relational expression is as follows:
uα(k)＝cos(θ(k))×ud(k)-sin(θ(k))×uq(k)。
in a specific implementation of the foregoing embodiment, further, u is processed in step s113α(k) Performing coordinate axis conversion to obtain output voltage uab(k) The specific process comprises the following steps:
will uα(k) Substituting into a preset sixth relational expression to obtain uab(k) (ii) a Wherein, the preset sixth relational expression is as follows:
uab(k)＝uα(k)-vs(k)。
in one embodiment of the present invention, the step s8 is performed by vdc(k) Obtaining an active current reference value i of the power grid sided-ref(k) The specific process comprises the following steps:
step s 81: calculating vdc(k) And a preset DC side voltage reference value vdc-refTo obtain the outer ring deviation e of the DC side voltagedc(k)；
Step s 82: by PI digital controller pair edc(k) Adjusting to obtain an active current reference value i of the power grid sided-ref(k)。
Referring to fig. 2 and fig. 3, fig. 2 is a circuit diagram of an embodiment of a method for controlling a single-phase converter according to the present invention, and fig. 3 is a flowchart of an embodiment of a method for controlling a single-phase converter according to the present invention, wherein LsEquivalent inductance of single-phase converter, RsIs the equivalent resistance of a single-phase converter, RLIs an equivalent load on the AC/DC side, CdcIs a DC side voltage support capacitor, S1～S4Four power switch tubes of a full-bridge circuit, wherein PI represents a PI digital controller, and a second-order generalized integrator phase-locked loop is used for analyzing vs(k) Obtaining a phase angle theta (k) and an angular speed omega (k); constructing active current and reactive current for realizing steps s2 and s4-s7 in FIG. 3 to obtain id(k) And iq(k) (ii) a Voltage coordinate axis transformation is used to implement step s112 to obtain uα(k) (ii) a Sinusoidal pulse width modulation for p uab(k) Pulse width modulation is performed, in this embodiment, a sinusoidal pulse width modulation process u is employedab(k) Obtaining the driving pulse S of four switching tubes11～S41Are respectively used for correspondingly controlling the switch tube S1～S4Make and break of (2).
According to the control method provided by the invention, the active current calibration parameter and the reactive current calibration parameter are obtained according to the angular speed of the grid side voltage in the current control period, and the active current and the reactive current are calibrated according to the two parameters. Because the angular velocity of the voltage is in direct proportion to the frequency of the voltage, in the method provided by the invention, the active current and the reactive power are calibrated according to the angular velocity of the voltage, which is equivalent to calibrating the active current and the reactive current according to the frequency of the voltage; in the invention, the active current and the reactive current are calibrated according to the frequency of the voltage, and the calibration of the active power and the reactive power is equivalent to the calibration of the active power and the reactive power according to the frequency of the voltage; the method provided by the invention can calibrate the active power and the reactive power of the power grid side according to the voltage frequency of the power grid side, so that the converter can calibrate the active power and the reactive power of the power grid side when the voltage frequency of the power grid side changes, the distribution of the active power and the reactive power can meet the requirements of a power system, and further the voltage frequency of the power grid side is more stable, so that the accuracy of the regulation of the active power and the reactive power in the power system and the stability of the voltage frequency are improved, and the accuracy of the regulation of the active power and the reactive power ensures that the voltage frequency of the power grid side is more stable, the condition of sudden voltage drop of the power grid side cannot occur, and further the quality of electric energy of the power grid side is improved.
Fig. 4 is a schematic structural diagram of a single-phase converter control device provided by the present invention, and fig. 4 is a schematic structural diagram of the single-phase converter control device provided by the present invention, where the single-phase converter control device specifically includes:
a data acquisition and storage module 1 for acquiring the current i of the power grid side in the current control periods(k) Grid side voltage vs(k) And a DC side voltage vdc(k) And save is(k)；
A stationary coordinate axis assignment module 2 for assigning the is(k) The stored power grid side current i n control periods before the current control periods(k-n) are α shaft currents i 'respectively in the stationary coordinate axes'α(k) And β shaft current i'β(k)；
Voltage angle analysis module 3 for vs(k) Carrying out angle analysis to obtain a phase angle theta (k) and an angular speed omega (k) of the power grid side voltage in the current control period;
an error phase calculation module 4 for obtaining an error phase between the phase difference in the ideal case and the phase difference in the actual case between the α axis and the β axis currents by ω (k)
A calibration parameter calculation module 5 for passing
Theta (K) obtaining an active current calibration parameter KdWith reactive current calibration parameter Kq；
A current coordinate axis conversion module 6 for pair i'α(k) And i'β(k) Performing coordinate axis conversion to obtain active current i 'in a rotating coordinate system'd(k) And reactive current i'q(k)；
A reference active current calculation module 8 for passing vdc(k) Obtaining an active current reference value i of the power grid sided-ref(k)；
A current deviation calculation module 9 for calculating id(k) And id-ref(k) To obtain an active current deviation Δ idCalculate iq(k) And a preset power grid side reactive current reference value iq-ref(k) To obtain a reactive current deviation delta iq；
A current-to-voltage conversion module 10 for passing Δ idAnd Δ iqObtaining an output voltage active component u'd(k) And output voltage reactive component u'q(k)；
A voltage coordinate axis conversion module 11 for passing through u'd(k) And u'q(k) Performing coordinate axis conversion to obtain output voltage uab(k)；
Driving a pulse modulation module 12 for generating a pulse signal by applying an output voltage uab(k) Pulse width modulation is carried out to obtain the monoThe drive pulse of each switch tube in the phase-change converter adjusts the parameters of the power grid side by controlling the on-off of the switch tube.
According to the control device provided by the invention, the active current calibration parameter and the reactive current calibration parameter are obtained according to the angular speed of the grid side voltage of the current control period, and the active current and the reactive current are calibrated according to the two parameters. Because the angular velocity of the voltage is in direct proportion to the frequency of the voltage, in the method provided by the invention, the active current and the reactive power are calibrated according to the angular velocity of the voltage, which is equivalent to calibrating the active current and the reactive current according to the frequency of the voltage; in the invention, the active current and the reactive current are calibrated according to the frequency of the voltage, and the calibration of the active power and the reactive power is equivalent to the calibration of the active power and the reactive power according to the frequency of the voltage; the method provided by the invention can calibrate the active power and the reactive power of the power grid side according to the voltage frequency of the power grid side, so that the converter can calibrate the active power and the reactive power of the power grid side when the voltage frequency of the power grid side changes, the distribution of the active power and the reactive power can meet the requirements of a power system, and further the voltage frequency of the power grid side is more stable, so that the accuracy of the regulation of the active power and the reactive power in the power system and the stability of the voltage frequency are improved, and the accuracy of the regulation of the active power and the reactive power ensures that the voltage frequency of the power grid side is more stable, the condition of sudden voltage drop of the power grid side cannot occur, and further the quality of electric energy of the power grid side is improved.
The above embodiments are only preferred embodiments of the present invention, and the above embodiments can be combined arbitrarily, and the combined embodiments are also within the scope of the present invention. The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A method of controlling a single-phase converter, comprising:
collecting the current i of the power grid side in the current control periods(k) Grid side voltage vs(k) And a DC side voltage vdc(k) And save said is(k)；
Will i iss(k) The stored power grid side current i n control periods before the current control periods(k-n) are α shaft currents i 'respectively in the stationary coordinate axes'α(k) And β shaft current i'β(k)；
For v is to vs(k) Carrying out angle analysis to obtain a phase angle theta (k) and an angular speed omega (k) of the power grid side voltage in the current control period;
obtaining an error phase between the phase difference of the α -axis current and the β -axis current in an ideal situation and the phase difference in an actual situation according to the omega (k)
According to the above
The theta (K) obtains an active current calibration parameter KdWith reactive current calibration parameter Kq；
To the i'α(k) And i 'to'β(k) Performing coordinate axis conversion to obtain active current i 'in a rotating coordinate system'd(k) And reactive current i'q(k)；
By said KdK toqTo the i'd(k) I 'to'q(k) Calibrating to obtain a calibrated active current id(k) And calibrating the reactive current iq(k)；
According to said vdc(k) Obtaining an active current reference value i of the power grid sided-ref(k)；
Calculating the id(k) And said id-ref(k) To obtain an active current deviation Δ idCalculating said iq(k) And a preset power grid side reactive current reference value iq-ref(k) To obtain a reactive current deviation delta iq；
According to said Δ idAnd said Δ iqObtaining an output voltage active component u'd(k) And output voltage reactive component u'q(k)；
To the u'd(k) And u's'q(k) Performing coordinate axis conversion to obtain output voltage uab(k)；
For the output voltage uab(k) And carrying out pulse width modulation to obtain driving pulses of each switching tube in the single-phase converter, and adjusting parameters of a power grid side by controlling the on-off of the switching tubes.
2. The method of claim 1, wherein said deriving from said ω (k) an error phase between an ideal case phase difference and an actual case phase difference between α -axis and β -axis currents
The specific process comprises the following steps:
substituting the omega (k) into a preset first relational expression to obtainThe above-mentioned
Wherein the preset first relation is as follows:
3. The method of claim 2, wherein said passing through is performed by said
The theta (K) obtains an active current calibration parameter KdWith reactive current calibration parameter KqThe specific process comprises the following steps:
will be described in
Substituting the theta (K) into a preset second relational expression to obtain the KdAnd said Kq(ii) a Wherein the preset second relation is as follows:
4. the method of claim 3, wherein said passing said KdK toqTo the i'd(k) I 'to'q(k) Calibrating to obtain a calibrated active current id(k) And calibrating the reactive current iq(k) The specific process comprises the following steps:
the K is addeddK toqI 'to'd(k) I 'to'q(k) Substituting into a preset third relation to obtain the id(k) And said iq(k) (ii) a Wherein the preset third relation is as follows:
id(k)＝Kd×i'd(k)
iq(k)＝i'q(k)+Kq×id(k)。
5. the method of claim 1, wherein said passing is to said u'd(k) And u's'q(k) Performing coordinate axis conversion to obtain output voltage uab(k) The specific process comprises the following steps:
u 'to the ω (k)'d(k) And u's'q(k) Calibrating to obtain the calibration value u of the active component of the output voltaged(k) And output voltage reactive component calibration value uq(k)；
For the ud(k) And said uq(k) Performing coordinate axis conversion to obtain an output voltage α axis component uα(k)；
For the uα(k) Performing coordinate axis conversion to obtain the output voltage uab(k)。
6. The method of claim 5, wherein said u 'is paired according to said ω (k)'d(k) And u's'q(k) Calibrating to obtain the calibration value u of the active component of the output voltaged(k) And output voltage reactive component calibration value uq(k) The specific process comprises the following steps:
mixing the ω (k), the u'd(k) U's'q(k) Substituting a preset fourth relational expression to obtain the ud(k) And said uq(k) (ii) a Wherein the preset fourth relation is as follows:
7. The method of claim 5, wherein the method is performed in a batch processCharacterized in that said pair of ud(k) And said uq(k) Performing coordinate axis conversion to obtain an output voltage α axis component uα(k) The specific process comprises the following steps:
subjecting said u tod(k) And said uq(k) Substituting a preset fifth relational expression to obtain the uα(k) (ii) a Wherein the preset fifth relational expression is as follows:
uα(k)＝cos(θ(k))×ud(k)-sin(θ(k))×uq(k)。
8. the method of claim 5, wherein said pair of u is saidα(k) Performing coordinate axis conversion to obtain the output voltage uab(k) The specific process comprises the following steps:
subjecting said u toα(k) Substituting a preset sixth relational expression to obtain the uab(k) (ii) a Wherein the preset sixth relational expression is as follows:
uab(k)＝uα(k)-vs(k)。
9. the method of claim 1, wherein said passing said vdc(k) Obtaining an active current reference value i of the power grid sided-ref(k) The specific process comprises the following steps:
calculating said vdc(k) And a preset DC side voltage reference value vdc-refTo obtain the outer ring deviation e of the DC side voltagedc(k)；
E is matched by PI digital controllerdc(k) Adjusting to obtain an active current reference value i of the power grid sided-ref(k)。
10. A single-phase converter control apparatus, comprising:
a data acquisition and storage module for acquiring the current i of the power grid side in the current control periods(k) Grid side voltage vs(k) And a DC side voltage vdc(k) And save said is(k)；
A stationary coordinate axis assignment module for assigning the is(k) The stored power grid side current i n control periods before the current control periods(k-n) are α shaft currents i 'respectively in the stationary coordinate axes'α(k) And β shaft current i'β(k)；
A voltage angle analysis module for analyzing vs(k) Carrying out angle analysis to obtain a phase angle theta (k) and an angular speed omega (k) of the power grid side voltage in the current control period;
an error phase calculation module for obtaining an error phase between the phase difference of the ideal situation and the phase difference of the actual situation between the α axis and the β axis currents through the omega (k)
A calibration parameter calculation module for passing said
The theta (K) obtains an active current calibration parameter KdWith reactive current calibration parameter Kq；
A current coordinate shaft conversion module for converting i'α(k) And i 'to'β(k) Performing coordinate axis conversion to obtain active current i 'in a rotating coordinate system'd(k) And reactive current i'q(k)；
A current calibration module for passing the KdK toqTo the i'd(k) I 'to'q(k) Calibrating to obtain a calibrated active current id(k) And calibrating the reactive current iq(k)；
A reference active current calculation module for passing the vdc(k) Obtaining an active current reference value i of the power grid sided-ref(k)；
A current deviation calculation module for calculating the id(k) And said id-ref(k) To obtain an active current deviation Δ idCalculating said iq(k) And a preset power grid side reactive current reference value iq-ref(k) To obtain a reactive current deviation delta iq；
Electric currentA voltage conversion module for passing the Δ idAnd said Δ iqObtaining an output voltage active component u'd(k) And output voltage reactive component u'q(k)；
A voltage coordinate shaft conversion module for converting u'd(k) And u's'q(k) Performing coordinate axis conversion to obtain output voltage uab(k)；
A drive pulse modulation module for modulating the output voltage uab(k) And carrying out pulse width modulation to obtain driving pulses of each switching tube in the single-phase converter, and adjusting parameters of a power grid side by controlling the on-off of the switching tubes.
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