CN107359872B - Multipath software phase locking device and method based on dynamic frequency modulation technology - Google Patents
Multipath software phase locking device and method based on dynamic frequency modulation technology Download PDFInfo
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Abstract
The invention relates to a multipath software phase locking device and method based on a dynamic frequency modulation technology, which is characterized in that: the method comprises the following steps: PI controller, carrier frequency modulation module anda cycle register of the controller; the phase locking process is as follows: the PI controller carries out closed-loop tracking on the reference path voltage phase locking angle error psi-0, the difference between the output quantity of the PI controller and the count value TPR corresponding to the carrier frequency under the controller clock is obtained and is used as the input of a carrier frequency modulation module, and then the carrier frequency module sends the updated triangular carrier period to a period register of the controller to realize the dynamic tracking of the period, thereby realizing the reference path phase locking; finally, phase differences of the multi-path power grid voltages Ua1 and Ua2.. Uan needing phase locking are calculated respectively to obtain corresponding fixed angle differences psi1，ψ2......ψnAnd realizing multipath phase locking, wherein n is more than or equal to 1. The invention can track the phase of the multi-path power grid voltage in real time, saves a hardware phase locking circuit, has good expansibility, and is simple and practical in the whole phase locking process only by adopting the phase locking of the reference path power grid.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a multipath software phase locking device and a phase locking method based on a dynamic frequency modulation technology.
Background
The application of phase locking in the field of power electronics and control theory is very common, and various phase locking methods are available, and are generally classified into hardware phase locking or software phase locking technologies. Along with the development of power electronics and automatic control industries, power electronic equipment not only has great dependence on the precision of a phase-locked loop, but also has certain requirements on the number of phase-locked loops due to the increasingly demanded function diversification of the market, for example, the existing active power filter in the rail transit industry is only used for compensating harmonic waves and reactive power of a load in a step-down transformer substation or a hybrid transformer substation, the load is generally small, the active power filter does not fully play the role of the active power filter, on the other hand, a 35kV power supply cable needs to compensate inductive reactive power due to the capacitance effect of the power supply cable, aiming at the special working condition, the power quality equipment of the power supply cable not only has the harmonic compensation function of a low-voltage side but also needs to monitor the reactive power of a high-voltage side in real time for compensation, so that the device needs two-way phase locking at the moment, and, the purpose of multi-path phase locking is achieved.
The existing phase locking technology comprises the following steps: the patent No. CN102545889A is a closed-loop phase-locking method and phase-locking device based on the instantaneous reactive power theory, in which the grid voltage is first converted to an α β coordinate system and then converted to a pq coordinate system to perform closed-loop control, although the ac component can be suppressed in a complex power supply environment, a large amount of coordinate system conversion occupies the resources of the controller, which is relatively large for resource consumption in the case of realizing multi-path phase-locking under the requirement of high switching frequency, and a three-phase system still needs to be constructed for calculation for a single-phase system. The phase-locked loop circuit of patent No. CN102035541A relates to a hardware phase-locked loop circuit for generating synchronous phases from a multi-phase reference signal, which can realize phase-locking of multiple phases, but needs to add hardware circuits and increases cost. For the latter method, the disadvantage is that the hardware cost needs to be increased, the hardware quantity is increased, the reliability of the device is reduced, and for the former software phase lock, in order to realize real-time tracking, carrier frequency modulation is generally needed, however, a plurality of power grid phase locks with phase differences cannot be directly adjusted in the same carrier frequency, or the angle difference of different positions of the power grid is measured by using the reason that the phase difference is a fixed phase angle caused by a transformer, and the testing method is troublesome for field operation of different devices.
Disclosure of Invention
1. The technical problem to be solved is as follows:
the invention aims to provide a single-phase voltage digital phase locking method to overcome the defects in the prior art. The technical problem to be solved by the invention is to provide a multipath software phase locking method based on a dynamic frequency modulation technology, the method is simple to use, high in compatibility and expandability, can realize multipath phase locking of different power grids under the same frequency, is high in phase locking precision through dynamic frequency modulation of carrier frequency, is fast in response to dynamic response of the power grids, can respond to phase fluctuation caused by power grid disturbance in one period, and really realizes dynamic phase locking.
2. The technical scheme is as follows:
in order to solve the above technical problems, the present invention adopts the following apparatus and method.
A multipath software phase locking device based on dynamic frequency modulation technology is characterized in that: the method comprises the following steps: the PI controller, the carrier frequency modulation module and a periodic register of the controller;
the phase locking process of the device is as follows: the PI controller carries out closed-loop tracking on the reference path voltage phase locking angle error psi-0, the difference between the output quantity of the PI controller and the count value TPR corresponding to the carrier frequency under the controller clock is obtained and is used as the input of a carrier frequency modulation module, and then the carrier frequency module sends the updated triangular carrier period to a period register of the controller to realize the dynamic tracking of the period, thereby realizing the reference path phase locking; finally, phase differences of the multi-path power grid voltages Ua1 and Ua2.. Uan needing phase locking are calculated respectively to obtain corresponding fixed angle differences psi1，ψ2......ψnAnd realizing multipath phase locking, wherein n is more than or equal to 1, and n is the number of multipath.
A multipath software phase locking method based on dynamic frequency modulation technology utilizes the multipath software phase locking device based on dynamic frequency modulation technology to realize multipath phase locking, and the phase locking process specifically comprises the following steps:
the method comprises the following steps: constructing a function of the voltage of the reference path Ua:
the difference phi between the actual power grid phase angle and the phase locking angle is zero, and the tracking target is 0 degree; then there is a functional formula:
since the frequency sine and cosine values of the actual grid are added up to 0 in a periodic manner, sin2wt and cos2wt in the formula a are 0, and the formula a can be changed as follows: Σ sin (wt + ψ) · cos (wt) ═ Σ sin ψ formula B
Similarly, Σ sin (wt + ψ) · sin (wt) ═ Σ cos ψ formula C exists
Dividing the formula B with the formula C to obtain tan psi, and then obtaining the current angle difference psi through arc tangent;
after the angle difference psi is solved, the PI regulation model is used for tracking closed-loop control, the output regulation quantity is converted into digital quantity under carrier frequency, the phase tracking is realized by regulating the size of carrier wave, and finally the angle difference psi gradually approaches to zero after the phase locking of a reference circuit;
step two: the functions for constructing the multi-path power grid voltage needing phase locking are respectively
After a period of time delay, namely after the phase locking of the power grid of the reference path in the step one is finished, starting a plurality of paths needing phase locking to calculate a phase angle, wherein the calculation process is the process of solving the angle difference psi in the step one, and the fixed angle difference psi is calculated1，ψ2......ψn(ii) a Assuming that the number of points of the periodic sampling is N, the number of points corresponding to the angle should be (psi)1*N)/2π，(ψ2*N)/2π......(ψnN)/2 pi, N is a positive integer;
step three: the current angle difference psi of the reference line voltage and the calculated angle difference psi of the multi-path power grid voltage needing phase locking1，ψ2......ψnRespectively making difference to respectively obtain the leading or lagging angles of the corresponding power grid voltage needing phase locking and a reference circuit;
step four: and converting the angle difference into digital quantity according to the sampling frequency and a master frequency clock of the controller to realize multipath phase tracking.
Furthermore, when the reference path is frequency-modulated and phase-locked in real time and other multiple paths dynamically track the phase with the reference path, the software phase-locking time of the reference path is 800 ms.
Further, the frequency of the reference path is the same as that of the multiple paths needing phase locking; or the frequency of the reference path is the same as the phase of the multiple paths needing phase locking.
3. Has the advantages that:
(1) the invention can track the phase of the multi-path power grid voltage in real time, and has very high tracking precision due to real-time tracking frequency modulation.
(2) The invention phase-locks through software, saves a hardware phase-locking circuit, reduces the cost, and also improves the reliability of the phase-locking of the equipment, thereby improving the reliability of the running of the equipment.
(3) The invention only adopts the phase locking of the power grid of the reference path, but the disturbance to the power grid can also respond to the phase fluctuation of other paths through the frequency modulation of the reference path because the adjacent power grids are connected through the transformer, and the whole phase locking process is simple and practical.
(4) The invention has the more important characteristics that the expansibility is good, the controller which wants to increase the number of phase-locked circuits only needs software upgrading, except the power grid voltage sampling which is needed by the controller, no special hardware circuit needs to be added, the multi-path phase-locked circuits which belong to the same frequency (such as power frequency 50HZ) can be phase-locked in principle, or the multi-path phase-locked circuits can be realized for the power grids with different frequencies and the same phase, and in addition, the periodic angle difference can be obtained by utilizing the thought of the invention for the power grids with different phases and different frequencies.
Drawings
FIG. 1 is a control schematic block diagram of the present invention;
FIG. 2 is a control flow chart of the present invention.
Detailed Description
The technical scheme of the invention is further explained by combining the drawings and the embodiment.
Fig. 1 is a block diagram of the phase lock according to the present invention. In the figure, PI is a PI controller, where the target tracking angle is 0, and the actual angle difference between the reference path and the phase-locked path is ψ, where PI is the PI controller, and its time domain expression
In the formula KpIs a constant of proportionality, KIIs an integral coefficient; TPR is the count value of the controller clock corresponding to the frequency of the triangular carrier wave, and PI tracking needs to be adjusted by subtracting the TPRAnd the count value corresponding to the section is tracked through the carrier frequency of one period, so that psi is slowly close to zero, dynamic tracking is realized, and when the phase locking of the reference circuit is finished (psi is basically zero), voltage signals of other circuits of the equipment are input into the PI controller. The specific process is as follows: the PI controller carries out closed-loop tracking on a reference path voltage phase locking angle error (psi-0), the obtained PI output quantity is different from a count value TPR corresponding to a carrier frequency under a controller clock, the difference is used as the input of a carrier frequency modulation module, the carrier frequency module sends an updated triangular carrier period to a period register of the controller to realize the dynamic tracking of the period, so that phase locking is realized, and finally, the Ua1 and the Ua21，ψ2......ψnAnd realizing multipath phase locking.
As shown in fig. 2, voltage sampling is performed during phase locking in a phase-locked system, and all controllers have an interrupt function, so that the process starts with a sampling signal, the controller in the present invention can be understood as a CPU, when the sampling interrupt signal is triggered, the controller samples each path of power grid voltage to obtain a reference path power grid voltage instantaneous value, calculates a phase angle difference between a reference path Ua and a theoretical value according to the above steps, converts a closed-loop modulation output PI _ OUT of angle tracking into a digital quantity of a triangular carrier period, and finally adjusts the period of the triangular carrier by making a difference between the carrier period TPR and the PI _ OUT, by dynamically adjusting the frequency and delaying 800ms (40 periods for power frequency), the phase difference between the theoretical angle and the actual power grid can be substantially close to 0, when the reference path delay time 800ms arrives, the other paths of power grid voltages Ua1 are further used, ua2.. Uan and Ua determine the angular difference ψ from the reference road Ua according to the inventive calculation procedure1，ψ2......ψn. Finally, combining the angle difference with the sampled frequency to obtain the number N of the periodically sampled points to obtain the point number difference (psi) corresponding to the angle difference1*N)/2π，(ψ2*N)/2π......(ψnN)/2 pi, the phase of other paths is obtained, and in the whole control process of the controller, because the reference path is in phase locking in real time, the other paths realize dynamic frequency modulation phase locking, and finally the phase is finally achievedTo the purpose of multiple phase locking.
Because the change of the grid voltage in one period (such as power frequency 50hz, one period is 20ms) is discretized into digital quantity for the controller to realize phase locking, the output of sampling and control is simply discretized into digital quantity, in the field of power electronics, if 200 points are sampled in one period, each discrete sampling point corresponding to one period of 20ms is 2 pi/200 radians, and for realizing the relative control of the lock, the angle is converted into the digital quantity after the angle difference is calculated.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (3)
1. A multipath software phase locking method based on a dynamic frequency modulation technology is characterized in that: the multipath software phase locking device based on the dynamic frequency modulation technology comprises: the PI controller, the carrier frequency modulation module and a periodic register of the controller;
the phase locking process of the device is as follows: the PI controller carries out closed-loop tracking on the reference path voltage phase locking angle error psi-0, the difference between the output quantity of the PI controller and the count value TPR corresponding to the carrier frequency under the controller clock is obtained and is used as the input of a carrier frequency modulation module, and the carrier frequency modulation module sends the updated triangular carrier period to a period register of the controller to realize the dynamic tracking of the period, thereby realizing the reference path phase locking; finally, phase differences of the multi-path power grid voltages Ua1 and Ua2.. Uan needing phase locking are calculated respectively to obtain corresponding fixed angle differences psi1，ψ2......ψnRealizing multi-path phase locking; wherein n is greater than or equal to 1; the method specifically comprises the following steps:
the method comprises the following steps: constructing a function of the voltage of the reference path Ua:
where Va is the instantaneous value of the voltage,ua is a sampled voltage value, the difference phi between an actual power grid phase angle and a phase locking angle is realized, and a tracking target is 0 degree; then there is a functional formula:
since the frequency sine and cosine values of the actual grid are added up to 0 in a periodic manner, sin2wt and cos2wt in the formula a are 0, and the formula a can be changed as follows: Σ sin (wt + ψ) · cos (wt) ═ Σ sin ψ formula B
Similarly, Σ sin (wt + ψ) · sin (wt) ═ Σ cos ψ formula C exists
Dividing the formula B with the formula C to obtain tan psi, and then obtaining the current angle difference psi through arc tangent;
after the angle difference psi is solved, the PI regulation model is used for tracking closed-loop control, the output regulation quantity is converted into digital quantity under carrier frequency, the phase tracking is realized by regulating the size of carrier wave, and finally the angle difference psi gradually approaches to zero after the phase locking of a reference circuit;
step two: the functions for constructing the multi-path power grid voltage needing phase locking are respectively
The voltage Ua1 and the voltage Ua2 … … and the voltage Uan represent n paths of sampling voltages needing phase locking; va1 is represented as the instantaneous value of the sampled voltage Ua1, Va2 is represented as the instantaneous value … … Van of the sampled voltage Ua2 is represented as the instantaneous value of the sampled voltage Uan;
after a period of time delay, namely after the phase locking of the power grid of the reference path in the step one is finished, starting a plurality of paths needing phase locking to calculate a phase angle, wherein the calculation process is the process of solving the angle difference psi in the step one, and the fixed angle difference psi is calculated1，ψ2......ψn(ii) a Assuming that the number of points of the periodic sampling is N, the number of points corresponding to the angle should be (psi)1*N)/2π，(ψ2*N)/2π......(ψnN)/2 pi, N is a positive integer;
step three: the current angle difference psi of the reference line voltage and the calculated angle difference psi of the multi-path power grid voltage needing phase locking1，ψ2......ψnRespectively making difference to respectively obtain the leading or lagging angles of the corresponding power grid voltage needing phase locking and a reference circuit;
step four: and converting the angle difference into digital quantity according to the sampling frequency and a master frequency clock of the controller to realize multipath phase tracking.
2. The multi-channel software phase locking method based on the dynamic frequency modulation technology as claimed in claim 1, wherein: and when the reference path is subjected to real-time frequency modulation phase locking and other multiple paths dynamically track the phase by using the reference path, the software phase locking time of the reference path is 800 ms.
3. The multi-channel software phase locking method based on the dynamic frequency modulation technology as claimed in claim 1, wherein: the frequency of the reference path is the same as that of a plurality of paths needing phase locking; or the phase of the reference path is the same as that of the multiple paths needing phase locking.
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| CN101777912A (en) * | 2010-01-15 | 2010-07-14 | 浙江大学 | Method for realizing software phase-locked loop with unfixed sampling frequency |
| CN102832639A (en) * | 2012-08-29 | 2012-12-19 | 华南理工大学 | DSP (digital signal processor) based energy-feedback electronic load grid-connected inverting system and control method thereof |
| CN202737484U (en) * | 2012-08-29 | 2013-02-13 | 华南理工大学 | DSP-based energy-feedback electronic load grid-connected inversion system |
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| CN101777912A (en) * | 2010-01-15 | 2010-07-14 | 浙江大学 | Method for realizing software phase-locked loop with unfixed sampling frequency |
| CN102832639A (en) * | 2012-08-29 | 2012-12-19 | 华南理工大学 | DSP (digital signal processor) based energy-feedback electronic load grid-connected inverting system and control method thereof |
| CN202737484U (en) * | 2012-08-29 | 2013-02-13 | 华南理工大学 | DSP-based energy-feedback electronic load grid-connected inversion system |
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