阅读说明：本技术 具备乘法结构和特殊三角函数的单相2倍频电网锁相方法 (Phase locking method for single-phase 2-frequency multiplication power grid with multiplication structure and special trigonometric function ) 是由 闫朝阳 王仕达 肖莹 李海强 赵丁选 张祝新 刘涛 于 2021-07-30 设计创作，主要内容包括：本发明提供一种具备乘法结构和特殊三角函数的单相2倍频电网锁相方法,首次构造相乘环节用于单相锁相,首次构造特殊三角函数运算系统获取2倍频分量,方法包括以下步骤：步骤1,提取得到单相电网电压V-(s)；步骤2,构造包含特殊三角函数运算系统的相乘环节；步骤3,将提取的电压信号和相乘环节相融合,得到2倍频信号：步骤4,将获得的2倍频信号经park变换运算,变换到dq坐标系下；步骤5,q轴的输出经过PI调节器,得到二倍电网频率,再经积分之后,得到二倍电网相角。本发明还提供了实现此方法的设备。本发明在理想电网与非理想电网中均适用,拓宽了锁相环的应用范围。(The invention provides a phase-locking method of a single-phase 2-frequency multiplication power grid with a multiplication structure and a special trigonometric function, wherein a multiplication link is constructed for single-phase locking for the first time, and a special trigonometric function operation system is constructed for the first time to obtain a 2-frequency multiplication component, and the method comprises the following steps: step 1, extracting to obtain single-phase power grid voltage V s (ii) a Step 2, constructing a multiplication link containing a special trigonometric function operation system; and step 3, fusing the extracted voltage signal with a multiplication link to obtain a frequency-doubled signal 2: step 4, the obtained 2 frequency multiplication signal is transformed to a dq coordinate system through park transformation operation; and 5, obtaining a double-power-grid frequency by the output of the q axis through a PI regulator, and obtaining a double-power-grid phase angle after integration. The invention also provides equipment for realizing the method. The invention is suitable for both ideal power grids and non-ideal power grids, and widens the application range of the phase-locked loop.)

1. A phase locking method for a single-phase 2-frequency multiplication power grid with a multiplication structure and a special trigonometric function is characterized in that: which comprises the following steps:

step 1, extracting the voltage of a single-phase power grid to obtain an alternating voltage V_s；

Step 2, constructing a multiplication link containing a special trigonometric function operation system;

the extracted grid voltage V_sMultiplies the sine value and the cosine value of the rotation angle theta of the dq coordinate system by the phase signal sin (ω t), and outputs V by controlling the q axis_gThe rotation angle theta of the dq coordinate system is consistent with the phase angle omega t of the grid voltage vector, so that the aim of tracking the grid voltage phase is fulfilled, and in a steady state, the d-axis component V_dEqual to the voltage amplitude V of the network voltage phase and the phase angle output by the feedback loop The phase angle of the grid voltage is doubled;

the multiplication link comprises a multiplier and a special trigonometric function operation system, and is used for replacing an orthogonal signal generator to construct and generate orthogonal 2 frequency multiplication components; the 2-frequency doubling single-phase power grid phase locking is realized based on the combination of trigonometric function square angle operation and power grid voltage;

the special trigonometric function operation system has the trigonometric function square angle multiplication formula characteristic of realizing a 2-time angle formula and outputs orthogonal 2-time frequency multiplicationComponent V_α' and V_β′；

And 3, fusing the extracted voltage signal with a multiplication link structure, and obtaining a frequency-doubled signal by using the following formula:

cos2θ＝1-2sin²θ (3)

sin2θ＝2sinθcosθ (5)

when the phase-locked loop system is in a steady state, i.e. ω t ═ θ,

wherein V is the amplitude of the voltage of the power grid; omega is the angular frequency of the voltage of the power grid;phase angle output for the feedback loop; theta is the rotation angle of the dq coordinate system; t is the time for the system to reach steady state, i.e. the time required for the rotation angle of the dq coordinate system to coincide with the phase angle of the grid voltage vector,V_α' and V_β' is extracted network voltage V_sAfter the constructed multiplication link, representing on an alpha and beta coordinate axis;

step 4, the obtained double frequency signal V_α' and V_β' transformation to dq coordinate system by park transformation operation, V_dAnd V_qIs a V_α' and V_β' representation on dq coordinate axis after park transformation;

step 5, outputting the output V of the q axis in the step 4_qObtaining the frequency which is twice of the synchronous angular frequency of the power grid through a PI regulator, obtaining the phase angle which is twice of the phase angle of the power grid after integration, dividing 2 by the obtained angular frequency to obtain the synchronous angular frequency of the power grid, and dividing 2 by the obtained phase angle to obtain the phase angle of the power grid.

2. The phase-locking method for the single-phase 2-frequency multiplication power grid with the multiplication structure and the special trigonometric function according to claim 1, characterized in that: the alternating voltage V in the step 1_sExpressed by formula (1):

V_s＝Vsin(ωt) (1)

where V is the voltage amplitude and ω is the voltage angular frequency.

3. The phase-locking method for the single-phase frequency-doubled power grid according to claim 1, wherein: v in said step 3_α' and V_β' are respectively represented as:

V_α′＝Vcos(2ωt)，V_β' Vsin (2 ω t), and V_α' and V_β' orthogonal.

4. The utility model provides a device that possesses single-phase 2 doubling of frequency electric wire netting lock of multiplication structure and special trigonometric function which characterized in that: it includes the following components: the device comprises an extractor, a multiplication link, a Park transformation arithmetic unit, a PI regulator, an integrator and a residue taking module; the specific connection structure is as follows:

the extractor extracts a single-phase grid voltage signal V from a single-phase power supply grid_s；

The multiplication link receives a power grid voltage signal V_sTwo paths of mutually orthogonal frequency doubling signals V are obtained_α' and V_β′；

The Park transformation operator converts the signal V_α' and V_β' as input, a Park transformation operation is performed to convert the signal V_α' and V_β' transformation to dq coordinate System, q-axis output is V_q；

The PI regulatorThe joint device is connected with the V_qThe output after the zero-crossing comparison is used as the input, and the output V is output by controlling the q axis_qThe rotation angle theta of the dq coordinate system is enabled to be consistent with the phase angle omega t of the power grid voltage vector, and therefore the purpose of tracking the power grid voltage phase is achieved; the output of the PI regulator and the double power frequency angular frequency omega_sAdding to obtain a synchronous angular frequency which is twice of the angular frequency of the power grid;

the integrator integrates the two times of the synchronous angular frequency of the power grid to obtain a phase angle which is two times of the phase angle of the power grid;

the residual module takes a phase angle which is twice of the phase angle of the power grid and a sine function period as input to obtain a periodic representation of the phase angle of the double power grid;

the obtained double phase angle is divided by 2 to obtain the phase angle of the power grid, and the feedback loop output phase angle in the residue taking module outputsIs twice the phase angle 2 theta of the power grid; will be provided withFeeding back to Park transformation arithmetic unit to form feedback closed loop and outputting V by controlling q axis_gThe rotation angle theta of the dq coordinate system and the phase angle of the grid voltage vector are zeroAnd the purpose of tracking the voltage phase of the power grid is achieved.

5. The apparatus of claim 4, wherein the phase-locked loop comprises a multiplication structure and a special trigonometric function, and is characterized in that: the specific structure of the multiplication link is as follows:

the multiplying link comprises a multiplier and a special trigonometric function operation system, and the multiplier multiplies two paths of input signals to obtain a single path of output signal; the special trigonometric function operation system has the characteristic of a trigonometric function square multiple angle formula, is used for realizing a 2 multiple angle formula and outputting positive phaseFrequency 2 multiplication component V of the cross_α' and V_β' the specific circuit structure is:

extraction of single-phase network voltage signal V from single-phase power supply network_sRespectively sent to the first input of a first multiplier and a second multiplier, sin theta is input to the second input of the first multiplier, and V is obtained by the first multiplier_ssin theta, inputting cos theta to the second input of the second multiplier, and obtaining V through the second multiplier_scos θ; because of V_sBecause θ is ω t and Vsin (ω t), the first multiplier outputs Vsin²(ω t), the second multiplier outputs Vcos (ω t) sin (ω t);

the output of the first multiplier and the output of the second multiplier are amplified by a multiplier amplifier to obtain 2Vsin²(ω t) and 2Vcos (ω t) sin (ω t), where 2Vcos (ω t) sin (ω t) is V in the quadrature signal_β′；

Will 2Vsin²(ω t) is input to a first input of the adder, an actual value | V | of the grid voltage is detected as a second input of the adder, and | V | -2Vsin is realized²(ωt)，|V|-2Vsin²(ω t) is V in the quadrature signal_α′。

Technical Field

The invention relates to the field of power grid power, in particular to a phase locking method for a single-phase 2-frequency multiplication power grid with a multiplication structure and a special trigonometric function.

Background

Tracking, locking the phase of the ac signal, and if necessary also providing frequency and amplitude information about the signal, is a primary function of the phase locked loop. In recent years, renewable energy grid-connected conversion technology has become a research hotspot in the technical field of power electronics. The grid-connected converter has wide development prospect in renewable energy distributed energy systems such as solar photovoltaic, wind power generation and the like. The operation of the grid-connected converter needs to be synchronous with the voltage of the power grid, and the waveform distortion is controlled to meet the quality requirement of the power grid. At the moment, a phase-locked loop is needed to be adopted to carry out phase locking on the power grid voltage to dynamically acquire phase information of the power grid voltage, and the performance of the phase-locked loop directly influences the control performance of the grid-connected converter on the waveform. The phase-locked loop technology is one of the cores of the grid-connected conversion technology, and the performance of the phase-locked loop technology directly influences the grid-connected control performance of the grid-connected converter. In addition, a harmonic detection link of the active filter is required for the phase-locked loop technology; when the phase tracking of the power network is carried out and the grid connection is carried out, the phase-locked loop technology is also needed to carry out synchronous tracking on the power grid voltage. The performance of the phase-locked loop is decisively affected. In view of the importance of the phase-locked loop, more and more researchers have studied the phase-locked loop to provide various control and design schemes for the phase-locked loop, so that the performance of the phase-locked loop is continuously improved and enhanced.

At present, there are technologies for obtaining 2-frequency multiplication from a three-phase system, such as the document "2-frequency multiplication grid synchronous phase-locking method based on a second-order generalized integrator SOGI when the grid voltage is unbalanced" and the document "novel 2-frequency multiplication phase-locking technology based on a sinusoidal amplitude integrator". The two documents theoretically analyze the reason of 2-frequency multiplication fluctuation generated under a dq rotating coordinate system under the condition of three-phase power grid voltage unbalance, and provide a 2-frequency multiplication phase locking method suitable for the three-phase power grid unbalance condition based on an SOGI link and an SAI link respectively by utilizing 2-frequency multiplication components extracted by matrix transformation.

However, in the single-phase system, there is no condition for generating the frequency multiplication 2 similarly to the three-phase system, and thus the frequency multiplication 2 cannot be obtained using the existing technique. This patent does not apply for any disclosed 2-frequency multiplication phase locking method, but only applies for the method proposed in this patent.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a method which enables 2-frequency multiplication characteristics to appear in a single-phase system by utilizing a constructed multiplication link containing a special trigonometric function operation system in a single-phase power grid, designs a single-phase 2-frequency multiplication power grid phase-locking method with a multiplication structure and a special trigonometric function which is universal in an ideal and non-ideal state, and specifically comprises the following steps:

step 1, extracting the voltage of a single-phase power grid to obtain an alternating voltage V_s；

Step 2, constructing a multiplication link containing a special trigonometric function operation system;

the extracted grid voltage V_sMultiplying the phase signal sin (ω t) by the sine value and cosine value (sin θ/cos θ) of the rotation angle θ of the dq coordinate system, and controlling the q-axis output V_qThe rotation angle theta of the dq coordinate system is consistent with the phase angle omega t of the grid voltage vector, so that the aim of tracking the grid voltage phase is fulfilled, and in a steady state, the d-axis component V_dEqual to the voltage amplitude V of the network voltage phase and the phase angle output by the feedback loopThe phase angle of the grid voltage is doubled; different from the existing single-phase power grid phase locking method for generating an orthogonal signal by using an orthogonal signal generator, the method is a 2-frequency multiplication single-phase power grid phase locking method realized by combining trigonometric function square angle multiplication and power grid voltage, the method is firstly provided for carrying out single-phase locking by the thought, the method for carrying out single-phase locking by using the thought does not exist in the prior art, the multiplication link comprises a multiplier and a special trigonometric function operation system, and the multiplication link is used for replacing the orthogonal signal generator to construct and generate an orthogonal phase orthogonal signalThe patent firstly proposes that the structure replaces an orthogonal signal generator and is used for constructing orthogonal 2-frequency multiplication components, and the prior art does not have the structure;

and 3, fusing the extracted voltage signal with a multiplication link structure, and obtaining a frequency multiplication signal 2 by using the following formula:

cos 2θ＝1-2 sin²θ (3)

sin 2θ＝2 sinθcosθ (5)

when the phase-locked loop system is in a steady state, i.e. ω t ═ θ,

wherein V is the amplitude of the voltage of the power grid; omega is the angular frequency of the voltage of the power grid;phase angle output for the feedback loop; theta is the rotation angle of the dq coordinate system; t is the time for the system to reach steady state, i.e. the time required for the rotation angle of the dq coordinate system to coincide with the phase angle of the grid voltage vector,V_α' and V_β' is extracted network voltage V_sAfter the constructed multiplication link, representing on an alpha and beta coordinate axis; the special trigonometric function operation system has the characteristic of a trigonometric function square multiple angle formula, is used for realizing a 2 multiple angle formula and outputting orthogonal 2 multiple frequency components V_α' and V_β' this patent first proposes such a structure for constructing quadrature 2-fold frequency components, prior artThere is no such structure and corresponding inputs and outputs of such structure;

step 4, the obtained 2 frequency multiplication signal V_α' and V_β' transformation to dq coordinate system by park transformation operation, V_dAnd V_qIs a V_α' and V_β' representation on dq coordinate axis after park transformation;

step 5, outputting the output V of the q axis in the step 4_qObtaining the frequency which is twice of the synchronous angular frequency of the power grid through a PI regulator, obtaining the phase angle which is twice of the phase angle of the power grid after integration, dividing 2 by the obtained angular frequency to obtain the synchronous angular frequency of the power grid, and dividing 2 by the obtained phase angle to obtain the phase angle of the power grid.

Preferably, the alternating voltage V in the step 1_sExpressed by formula (1):

V_s＝V sin(ωt) (1)

where V is the voltage amplitude and ω is the voltage angular frequency.

Preferably, V in said step 3_α' and V_β' are respectively represented as:

V_α′＝V cos(2ωt),V_β' V sin (2 ω t), and V_α' and V_β' orthogonal.

The invention also provides a device for phase locking of the single-phase 2-frequency multiplication power grid, which comprises the following components: the device comprises an extractor, a multiplication link, a Park transformation arithmetic unit, a PI regulator, an integrator and a residue taking module; the specific connection structure is as follows:

the extractor extracts a single-phase grid voltage signal V from a single-phase power supply grid_s；

The multiplication link receives a power grid voltage signal V_sObtaining two paths of 2 frequency multiplication signals V orthogonal to each other_α' and V_β′；

The Park transformation operator converts the signal V_α' and V_β' as input, a Park transformation operation is performed to convert the signal V_α' and V_β' transformation to dq coordinate System, q-axis output is V_q；

The PI regulator is toV_qThe output after the zero-crossing comparison is used as the input, and the output V is output by controlling the q axis_qThe rotation angle theta of the dq coordinate system is enabled to be consistent with the phase angle omega t of the power grid voltage vector, and therefore the purpose of tracking the power grid voltage phase is achieved; the output of the PI regulator and the double power frequency angular frequency omega_sAdding to obtain a synchronous angular frequency which is twice of the angular frequency of the power grid;

the integrator integrates the two times of the synchronous angular frequency of the power grid to obtain a phase angle which is two times of the phase angle of the power grid;

the residual module takes a phase angle which is twice of the phase angle of the power grid and a sine function period as input to obtain a periodic representation of the phase angle of the double power grid;

the obtained double phase angle is divided by 2 to obtain the phase angle of the power grid, and the feedback loop output phase angle in the residue taking module outputsIs twice the phase angle 2 theta of the power grid; will be provided withFeeding back to Park transformation arithmetic unit to form feedback closed loop and outputting V by controlling q axis_qThe rotation angle theta of the dq coordinate system and the phase angle of the grid voltage vector are zeroAnd the purpose of tracking the voltage phase of the power grid is achieved.

Preferably, the specific structure of the multiplication link is as follows:

the multiplying link comprises a multiplier and a special trigonometric function operation system, and the multiplier multiplies two paths of input signals to obtain a single path of output signal; the special trigonometric function operation system has the characteristic of a trigonometric function square multiple angle formula, is used for realizing a 2 multiple angle formula and outputting orthogonal 2 multiple frequency components V_α' and V_β' the specific circuit structure is:

extraction of single-phase network voltage signal V from single-phase power supply network_sAre respectively sent to the firstThe first input of the multiplier and the second multiplier, sin theta is input to the second input of the first multiplier, and V is obtained through the first multiplier_ssin theta, inputting cos theta to the second input of the second multiplier, and obtaining V through the second multiplier_scos θ; because of V_sBecause θ is ω t, the first multiplier outputs V sin (ω t)²(ω t), the second multiplier outputs V cos (ω t) sin (ω t);

the output of the first multiplier and the output of the second multiplier are amplified by a multiplier amplifier respectively to obtain 2V sin²(ω t) and 2V cos (ω t) sin (ω t), where 2V cos (ω t) sin (ω t) is the V in the orthogonal signal_β′；

2V sin²(ω t) is input to the first input of the adder, the actual value | V | of the grid voltage is detected as the second input of the adder, and | V | to 2V sin is realized²(ωt)，|V|-2V sin²(ω t) is V in the quadrature signal_α′。

Compared with the prior art, the invention has the following advantages:

1. the invention uses the multiplier and the special trigonometric function operation system to construct the multiplication link, uses the multiplication link to construct the frequency-2 multiplication signal, uses the constructed frequency-2 multiplication signal to carry out phase locking by utilizing the second harmonic signal, and has simple structure and clear thought.

2. The idea of constructing a multiplication link by using a multiplier and a special trigonometric function operation system to carry out 2-frequency multiplication signal construction and using the signal to carry out phase locking is absent in the prior art; the structure of a special trigonometric function operation system and a multiplication link constructed by the invention is not available in the prior art; the input and output forms of the 2-frequency multiplication component for single-phase locking are not available in the prior art.

3. The invention is suitable for both ideal and non-ideal power grids, obtains double power grid angular frequency through a multiplier structure and a special trigonometric function operation system, and synchronously tracks power grid signals by using the double power grid angular frequency. The method can accurately and synchronously track the power grid signals in an ideal environment, and can also accurately and synchronously track and acquire the power grid signals in a non-ideal power grid environment, so that the application range of the phase-locked loop is greatly expanded, and the rapidity and the accuracy of tracking the power grid synchronous signals are improved.

Drawings

FIG. 1 is a block diagram of a conventional quadrature signal generator based phase locked loop;

FIG. 2 is a block diagram of the phase-locking device of the single-phase 2-frequency multiplication power grid with a multiplication structure and a special trigonometric function according to the present invention;

FIG. 3 is a block diagram of the input signal and multiplier combination according to the present invention;

FIG. 4 is a block diagram of a special trigonometric function calculation system constructed in accordance with the present invention;

FIG. 5 is a block diagram illustrating the structure of a multiplication link constructed by combining the key number operations of FIGS. 3 and 4;

FIG. 6 shows two orthogonal signals V generated by multiplying single-phase AC signals in the present invention_α' and V_β' waveform diagram;

FIG. 7 is a diagram of two quadrature signals V generated by a quadrature signal generator from a single-phase AC signal in the prior art_αAnd V_βA waveform diagram of (a).

Detailed Description

In order to better understand the technical solution of the present invention, the following detailed description is made with reference to the accompanying drawings and examples. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

The invention provides a phase locking method for a single-phase 2-frequency multiplication power grid with a multiplication structure and a special trigonometric function, which comprises the following steps of constructing a multiplication link by using a multiplier and a special trigonometric function operation system, constructing a 2-frequency multiplication signal by using the multiplication link, and locking the phase by using the constructed 2-frequency multiplication signal and a second harmonic signal, and specifically comprises the following steps of:

step 1, extracting the voltage of a single-phase power grid to obtain an alternating voltage V_sExpressed by formula (1):

V_s＝V sin(ωt) (1)

where V is the voltage amplitude and ω is the voltage angular frequency.

Step 2, constructing a multiplication link containing a special trigonometric function operation system,

the multiplication link needs to construct the grid voltage V in advance_sThe term "V sin (ω t) frequency ω is a precondition for changing to 2 times the frequency 2 ω by a trigonometric square angle equation.

By extracting the voltage V of the power network_sMultiplies the sine value and the cosine value (sin θ/cos θ) of the rotation angle θ of the dq coordinate system by the phase signal sin (ω t) of (1). By controlling q-axis output V_qAnd when the rotation angle theta of the dq coordinate system is zero, the rotation angle theta of the dq coordinate system is consistent with the phase angle omega t of the power grid voltage vector, so that the purpose of tracking the power grid voltage phase is achieved. At steady state, d-axis component V_dEqual to the voltage amplitude V of the network voltage phase and the phase angle output by the feedback loopI.e. twice the phase angle of the grid voltage.

And 3, fusing the extracted voltage signal with a multiplication link structure, and obtaining a 2-frequency multiplication signal by using the following formula:

cos 2θ＝1-2 sin²θ (3)

sin 2θ＝2 sinθcosθ (5)

when the phase-locked loop system is in a steady state, i.e. ω t ═ θ,

wherein V is the amplitude of the voltage of the power grid; omega is the angular frequency of the voltage of the power grid;phase angle output for the feedback loop; theta is the rotation angle of the dq coordinate system; t is the time for the system to reach steady state, i.e. the time required for the rotation angle of the dq coordinate system to coincide with the phase angle of the grid voltage vector,V_α' and V_β' is extracted network voltage V_sAfter the constructed multiplication link, the representation is on the alpha and beta coordinate axes, wherein V_α′＝V cos(2ωt),V_β′＝V sin(2ωt),V_α' and V_β' orthogonal.

Different from the traditional single-phase power grid voltage V_sTwo orthogonal V paths need to be generated by an orthogonal signal generator_αAnd V_β，V_α＝V cos(ωt)；V_βSingle-phase mains voltage V ═ V sin (ω t)_sAnd respectively representing the components on the alpha and beta coordinate axes by a traditional method. The invention converts the single-phase power grid voltage V_sV is obtained through multiplication links_sComponent V on the α β coordinate axis_α' and V_β′，V_α′＝V cos(2ωt)；V_β′＝V sin(2ωt)。

The invention can also accurately and synchronously track the power grid signal under the non-ideal power grid because the invention initially tracks the voltage V of the single-phase power grid_sWhen the components on the alpha and beta coordinate axes are constructed, the components are extracted and constructed according to the ideal situation, namely even when the grid voltage amplitude fluctuates back and forth, the relation between the grid voltage actual amplitude V and the absolute value | V | of the grid voltage detected by calculation is formed, wherein | V | is V,and the closed loop PI control of the original whole phase-locked loop system is equivalent to weakening the influence of non-ideal working conditions from the beginning, so the method is also suitable for the non-ideal power grid environment.

Step 4, the obtained 2 frequency multiplication signal V_α' and V_β' transformation to dq coordinate system by park transformation operation, V_dAnd V_qIs a V_α' and V_β' representation on dq coordinate axis after park transformation.

Step 5, outputting the output V of the q axis in the step 4_qObtaining the frequency which is twice of the synchronous angular frequency of the power grid through a PI regulator, obtaining the phase angle which is twice of the phase angle of the power grid after integration, dividing 2 by the obtained angular frequency to obtain the synchronous angular frequency of the power grid, and dividing 2 by the obtained phase angle to obtain the phase angle of the power grid.

In order to realize the method, the invention also provides a device for phase locking of the single-phase 2-frequency multiplication power grid.

FIG. 1 is a block diagram of a phase-locked structure of a conventional single-phase power grid, in which a virtual path and an actual signal V are generated from an extracted single-phase power grid voltage through an orthogonal signal generator_αOrthogonal virtual signal V_β. Then the set of signals V_αAnd V_βCarrying out Park conversion operation, converting to dq coordinate system, and outputting V of q axis_qAnd obtaining the synchronous angular frequency of the power grid through a PI regulator, and obtaining the phase angle of the power grid after integration. However, this method is only suitable for use under ideal grid voltage conditions, and if the grid voltage is not ideal, there is a problem.

The phase-locking device of the single-phase 2-frequency multiplication power grid is shown in fig. 2, and does not use an orthogonal signal generator structure of a traditional single-phase-locked loop, but acquires a group of orthogonal 2-frequency multiplication alternating current signals for phase locking by constructing a multiplication link. On the basis of the single-phase 2-frequency-multiplication power grid phase-locking device structure, the formed novel phase-locking method not only can accurately acquire the synchronous signals of a power grid in an ideal state, but also can accurately acquire the synchronous signals of the power grid in a non-ideal environment. Meanwhile, the angular frequency which is twice of the power grid synchronous signal is constructed and applied to phase locking, so that the rapidity of the phase locking is further improved.

The phase locking device for the single-phase 2-frequency multiplication power grid comprises the following components: the system comprises an extractor, a multiplication link, a Park transformation arithmetic unit, a PI regulator and an integrator; the specific connection structure is as follows:

extractor extracts single-phase network voltage signal V from single-phase power supply network_s(ii) a Converting the network voltage signal V_sTwo paths of 2 frequency multiplication signals V orthogonal to each other are obtained through multiplication links_α' and V_β'; then the set of signals V_α' and V_βInputting the data into a Park transformation arithmetic unit to perform Park transformation operation, and transforming the data into a dq coordinate system; then the output V of the q axis_qAfter zero-crossing comparison, the output is transmitted to a PI regulator, and the output V is output by controlling a q axis_qThe rotation angle theta of the dq coordinate system is enabled to be consistent with the phase angle omega t of the power grid voltage vector, and therefore the purpose of tracking the power grid voltage phase is achieved; output of PI regulator and double power frequency angular frequency omega_sAdding to obtain a synchronous angular frequency which is twice of the angular frequency of the power grid; then, integrating the two times of synchronous angular frequency of the power grid through an integrator to obtain a phase angle which is two times of the phase angle of the power grid; finally, inputting the phase angle which is twice the phase angle of the power grid and the period of the sine function into a residue module to obtain the periodic representation (the period interval is 0-2 pi) of the phase angle of the twice power grid; the obtained double phase angle is divided by 2 to obtain the phase angle of the power grid, and the feedback loop output phase angle output in the residue module is simultaneously obtainedIs twice the phase angle 2 theta of the power grid; will be provided withFeeding back to Park transformation arithmetic unit to form feedback closed loop and outputting V by controlling q axis_qThe rotation angle theta of the dq coordinate system and the phase angle of the grid voltage vector are zeroAnd the consistency is achieved, so that the purpose of tracking the voltage phase of the power grid is achieved.

The multiplying link comprises a multiplier and a special trigonometric function operation system, wherein the multiplier multiplies one path of input signals by the input signals of the invention to obtain one path of output signals as shown in figure 3; a special trigonometric function operation system is shown in FIG. 4, which has threeThe characteristics of the angle function square multiple angle formula can be used to realize the double angle formula, the two are combined to obtain the multiplication link for constructing 2 frequency multiplication, as shown in fig. 5, the output is the orthogonal 2 frequency multiplication component V_α' and V_β' the specific circuit structure is:

extraction of single-phase network voltage signal V from single-phase power supply network_sRespectively sent to the first input of a first multiplier and a second multiplier, sin theta is input to the second input of the first multiplier, and V is obtained by the first multiplier_ssin theta, inputting cos theta to the second input of the second multiplier, and obtaining V through the second multiplier_scos θ. Because of V_sBecause θ is ω t, the first multiplier outputs V sin (ω t)²(ω t), the second multiplier outputs V cos (ω t) sin (ω t);

the output of the first multiplier and the output of the second multiplier are amplified by a multiplier amplifier respectively to obtain 2V sin²(ω t) and 2V cos (ω t) sin (ω t), where 2V cos (ω t) sin (ω t) is the V in the orthogonal signal_β′；

2V sin²(ω t) is input to the first input of the adder, the actual value | V | of the grid voltage is detected as the second input of the adder, and | V | to 2V sin is realized²(ωt)，|V|-2V sin²(ω t) is V in the quadrature signal_α′。

To further illustrate the advantages of the present invention, the quadrature signal using the single-phase 2-frequency multiplication grid phase-locking method is compared with the quadrature signal in the conventional phase-locking method based on the quadrature signal generator. FIG. 6 shows a quadrature signal V in the method of the present invention_α' and V_β' fig. 7 is a waveform diagram showing a quadrature signal V in the conventional quadrature signal generator-based phase locking method_αAnd V_βA waveform diagram of (a). From a comparison of fig. 6 and 7, it can be seen that the conventional frequency is half the frequency of the method of the present invention. It is known to those skilled in the art that the larger the frequency f, the larger the angular frequency ω, and the shorter the required phase-lock period time t when θ is fixed, the better the rapidity of the method.

Finally, it should be noted that: the above-mentioned embodiments are only used for illustrating the technical solution of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will 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 or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.