JP2018093703A - Phase synchronization method for phase synchronization circuit to be used for grid connection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase synchronization method for a phase synchronization circuit, the phase synchronization method being capable of keeping normal operation by overcoming problems such as input commercial power supply voltage's distortion and frequency change or the like to achieve accurate synchronization, and making an inverter hardly receive influence of interference of a commercial power supply.SOLUTION: A phase synchronization method for a phase synchronization circuit of the present invention is used for a grid connection system, the phase synchronization method for the phase synchronization circuit including a conversion signal generation step, error calculation step, frequency correction signal acquisition step, angle signal acquisition step, and synchronization signal generation step to detect voltage of a commercial power supply so as to calculate the magnitude of an error value before making the error value be lower or zero using proportional integral adjustment. By the steps described above, voltage distortion and frequency change in input commercial power supply are overcome to acquire an effect of accurately achieving synchronization and, in addition to this, the method acquires an advantage of high-speed response, achieves an effect having a wide frequency range, is used for tracking a power generation facility such as a diesel oil power generator, and is capable of expanding an application range of an inverter.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a phase synchronization method for a phase synchronization circuit, and more particularly to a phase synchronization method for a phase synchronization circuit used in a grid connection system.

  The grid connection system usually has an inverter circuit that can be controlled digitally. The inverter circuit detects a commercial power supply voltage and generates a sine synchronization signal. The sine synchronization signal is converted into a current circuit or an alternating current in the inverter circuit. By providing the voltage control circuit with the same voltage, frequency, and phase of the inverter circuit as the voltage, frequency, and phase of the commercial power supply, it is possible to perform power flow control between the two. .

As shown in FIG. 1, the conventional inverter circuit 1000 detects a zero cross point of the commercial power supply voltage V _S using a comparator or an operational amplifier 1100, and the frequency of the zero cross signal S _ZERO through a digital capture 1200. The zero cross signal S _ZERO is also used to reset a default sine wave table (Sine Table) 1300 to generate a synchronous sine wave signal S _SIN necessary for the inverter circuit 1000.

  However, when the above-described inverter circuit 1000 is used, problems such as distortion of the commercial power supply voltage and vibration of the zero-cross signal of the detection circuit cause vibrations in the reset signal and further cause problems of vibration of the sine wave table. In order to solve this problem, it is possible to improve the commercial power supply voltage waveform detected using a low-pass filter, or to reduce the signal oscillation problem with a comparator having hysteresis. It causes a phase delay problem in the sine wave table and is difficult to apply to applications with a relatively wide voltage frequency change.

  The object of the present invention is to overcome the problems such as distortion of the input commercial power supply voltage and frequency change to achieve accurate synchronization, making the inverter less susceptible to commercial power supply interference and maintaining normal operation Another object of the present invention is to provide a phase synchronization method of a phase synchronization circuit that can be performed.

  Another object of the present invention is to provide a phase-locked loop that has the advantage of high-speed response, has a wide frequency range, can be used for tracking power generation equipment such as a diesel oil generator, and can expand the application range of an inverter. It is an object to provide a phase synchronization method.

  In order to achieve the above object and other objects, the phase synchronization method of the phase synchronization circuit of the present invention is used in a grid connection system, and the phase synchronization method of the phase synchronization circuit includes a conversion signal generation step, an error calculation step, It includes a frequency correction signal acquisition step, an angle signal acquisition step, and a synchronization signal generation step.

  In the conversion signal generation step, a first conversion signal and a second conversion signal are generated by detecting a voltage of a commercial power supply, the first conversion signal is in a first function format, and the second conversion signal is a second conversion signal. It is a function form. In the error calculation step, an error value is obtained by calculating from the values of the first conversion signal, the second conversion signal, the first synchronization signal, and the second synchronization signal, and the first synchronization signal is the second function. And the second synchronization signal is in the first function format. In the frequency correction signal acquisition step, an error signal having the error value is input to a proportional integrator to acquire a frequency correction signal. In the angle signal acquisition step, first, an adjustment frequency is acquired by adding the frequency correction signal and the original frequency, and then the adjustment frequency is integrated to acquire an angle signal. In the synchronization signal generation step, a value corresponding to the angle value of the angle signal is obtained by referring to the first function table and the second function table, respectively, and the angle value of the angle signal is set in the first function table. The corresponding value is the value of the first synchronization signal, and the value corresponding to the angle value of the angle signal in the second function table is the value of the second synchronization signal.

  In one embodiment of the phase synchronization method of the phase synchronization circuit of the present invention, the first function table is a sine wave table, the second function table is a cosine wave table, and the first function table is a sine wave table. The phase difference between the phase of one synchronization signal and the phase of the second synchronization signal is 90 degrees.

  In an embodiment of the phase synchronization method of the phase synchronization circuit of the present invention, the error calculation step includes a first product acquisition step, a second product acquisition step, and an error value acquisition step. In the first product acquisition step, the values of the first conversion signal and the first synchronization signal are combined to acquire a first product. In the second product acquisition step, the second product is acquired by synergizing the values of the second conversion signal and the second synchronization signal. In the error value acquisition step, the error value is acquired by subtracting the second product from the first product.

  In one embodiment of the phase synchronization method of the phase synchronization circuit of the present invention, an angle limiting step is further included between the angle signal acquisition step and the synchronization signal generation step, and the angle value of the angle signal is first determined by a range limiter. Limit within a certain range.

  In one embodiment of the phase synchronization method of the phase synchronization circuit of the present invention, the commercial power supply has a three-phase voltage, and in the conversion signal generation step, the three-phase voltage of the commercial power supply is detected to detect the first conversion signal. And the second converted signal is generated.

  In one embodiment of the phase synchronization method of the phase synchronization circuit of the present invention, the commercial power supply has a single-phase voltage, and in the conversion signal generating step, the single-phase voltage of the commercial power supply is detected to detect the first conversion signal. And generating the second converted signal.

  In one embodiment of the phase synchronization method of the phase synchronization circuit of the present invention, the conversion signal generation step further includes a sampling step, the sampling is performed on the detected voltage of the commercial power source, and the first conversion signal is converted to the first conversion signal. Generate.

  In one embodiment of the phase synchronization method of the phase synchronization circuit of the present invention, the conversion signal generation step further includes a delay step, and the first conversion signal is delayed to generate the second conversion signal.

  As a result, the phase synchronization method of the phase synchronization circuit of the present invention overcomes the voltage distortion and frequency change of the input commercial power supply through the above-described steps, and can achieve the effect of achieving accurate synchronization, and also has a high-speed response. It has advantages and has the effect of having a wide frequency range, can be used for tracking power generation equipment such as diesel oil generators, and can expand the application range of inverters.

It is the schematic which shows the conventional inverter electric circuit. It is a system block diagram of one Example of the grid connection system which uses the phase synchronization method of the phase synchronization circuit of this invention. It is a flowchart which shows one Example of the phase synchronization method of the phase synchronization circuit of this invention. It is a flowchart which shows another Example of the phase-synchronization method of the phase-synchronization circuit of this invention. It is the schematic which shows one Example of this invention when a commercial power supply has a three-phase voltage. It is a simulation circuit diagram of one Example of this invention when a commercial power supply has a three-phase voltage. It is a simulation result figure of one Example of this invention when a commercial power supply has a three-phase voltage. It is the schematic which shows one Example of this invention when a commercial power supply has a single phase voltage. It is a simulation circuit diagram of one Example of this invention when a commercial power supply has a single phase voltage. It is a simulation result figure of one Example of this invention when a commercial power supply has a single phase voltage.

  In order that the objects, features, and advantages of the present invention may be fully understood, the present invention will be described in detail below by combining specific embodiments with the accompanying drawings.

  Please refer to FIG. FIG. 2 shows a system block diagram of an embodiment of the grid connection system 100 using the phase synchronization method of the phase synchronization circuit of the present invention. As shown in FIG. 2, the grid connection system 100 includes a phase synchronization circuit 110, an insulation protection element 120, a voltage controller 130, a current controller 140, a sinusoidal pulse width modulation (Sinusoidal PWM) driver 150, and an inverter 160. 160 includes a DC bus 161, a MOSFET module 162, and an LC filter 163, and the LC filter 163 is connected to a commercial power grid.

Among them, the phase synchronization circuit 110 detects a commercial power supply voltage V _S, gradually reduce the error of the commercial power supply voltage V _S (e.g., phase difference) between the output signal by the internal tracking adjustment mechanism (e.g. sinusoidal signal) The power flow control between the two can be performed by setting the voltage, frequency, and phase of the inverter 160 to be the same as the voltage, frequency, and phase of the commercial power source.

  It should be noted that the grid connection system 100 of FIG. 2 is only an example of a number of grid connection systems, and the application range of the phase synchronization method of the phase synchronization circuit of the present invention is limited to the grid connection system 100 of FIG. Absent. The phase synchronization method of the phase synchronization circuit of the present invention can be applied to various types of grid connection systems including at least an on-grid renewable energy power generation system and an uninterruptible power supply (UPS).

  Next, referring to FIG. FIG. 3 is a flowchart of the phase synchronization method of the phase synchronization circuit of the present invention. As shown in FIG. 3, the phase synchronization method of the phase synchronization circuit includes a conversion signal generation step S110, an error calculation step S120, a frequency correction signal acquisition step S130, an angle signal acquisition step S140, and a synchronization signal generation step S150. And including.

The conversion signal generation step S110 detects the commercial power supply voltage V _S and generates the first conversion signal S1 and the second conversion signal S2. In one embodiment, since the value of the first conversion signal S1 is V _m sin (ωt) and the first conversion signal S1 is in the form of a sine function, the sine function is called a first function, and the first conversion signal The signal S1 is in the first function form. Since the value of the second conversion signal S2 is V _m cos (ωt) and the second conversion signal S2 is in the form of a cosine function, the cosine function is referred to as a second function, and the second conversion signal S2 is the second It is a function form. In addition, V _m represents the root mean square voltage of the commercial power source and represents the ω original frequency. t represents time.

  It should be noted that in the embodiment, the first function and the second function are a sine function and a cosine function, respectively, but are not limited thereto. For example, in other possible embodiments, the first function and the second function are The function may have a cosine function format, and the second function may correspond to a sine function format.

In the error calculation step S120, an error value e is obtained by calculating with the values of the first conversion signal S1, the second conversion signal S2, the first synchronization signal S3, and the second synchronization signal S4. In one embodiment, the value of the first synchronization signal S3 is cos (ω ₁ t), and the first synchronization signal S3 is in the cosine function format, so the first synchronization signal S3 is in the second function format. Since the value of the second synchronization signal S4 is sin (ω ₁ t) and the second synchronization signal S4 is in the sine function format, the second synchronization signal S4 is in the first function format. In addition, ω ₁ represents the adjusted frequency after frequency correction.

For example, the error value e can be calculated using the following formula.
e = V _m {sin (ωt) cos (ω ₁ t) −cos (ωt) sin (ω ₁ t)}.

Among them, V _m sin (ωt) cos (ω ₁ t) is called a first product, and the first product is equal to a result of synergizing the values of the first conversion signal S1 and the first synchronization signal S3. V _m cos (ωt) sin (ω ₁ t) is called a second product, and the second product is equal to the result of synergizing the values of the second conversion signal S2 and the second synchronization signal S4. The error value e is equal to a value obtained by subtracting the second product from the first product.

  In the frequency correction signal acquisition step S130, an error signal having the error value e is input to a proportional integrator to acquire a frequency correction signal S5. The value of the frequency correction signal S5 is Δω.

In the angle signal acquisition step S140, after acquiring the adjustment frequency omega ₁ is first additive said frequency correction signal △ omega and the original frequency omega, obtains the angle signal θ by integrating the adjustment frequency omega _1. That is, ω ₁ = ω + Δω, and θ is obtained after integrating ω ₁ .

が得られる。 The synchronization signal generation step S150 refers to the first function table T1 and the second function table T2, respectively, and acquires a value corresponding to the angle value of the angle signal θ. In the embodiment, the first function table T1 is a cosine wave table, and the second function table T2 is a sine wave table. The phase difference between the phase of the first synchronization signal S3 and the phase of the second synchronization signal S4 is 90 degrees. Therefore, when θ = 60 °, cos (60 °) = 1/2 is obtained with reference to the first function table T1, and with reference to the second function table T2.

Is obtained.

  Furthermore, as shown in FIG. 4, an angle limiting step S160 is included between the angle signal acquisition step S140 and the synchronization signal generation step S150, and the angle limiting step S160 is an angle value of the angle signal θ by a range limiter. Is limited to a certain range (for example, limited to a range of 0 to 2π), and the angle limiting step S160 is performed to confirm that the angle value of the angle signal θ is always within a predetermined range after conversion. And the dimensions of the first function table T1 and the second function table T2 are appropriately controlled. For example, when it is not necessary to consider θ = 2π to 4π, the problem of the corresponding values in the first function table T1 and the second function table T2 is that θ is always in the range of 0 to 2π after the conversion. And, after conversion, the values of sin θ and cos θ are the same when calculated.

である。 For the angle value of the angle signal θ, the corresponding value in the first function table T1 is the value of the first synchronization signal S3, that is, the value of the first synchronization signal S3 is cos (ω ₁ t). As for the angle value of the angle signal θ, the corresponding value in the second function table T2 is the value of the second synchronization signal S4, that is, the value of the second synchronization signal S4 is sin (ω ₁ t). . For example, when θ = 60 °, the value of the first synchronization signal S3 is 1/2, and the value of the first synchronization signal S4 is

It is.

The purpose of phase synchronization can be achieved by making the error e gradually zero by proportional-integral adjustment through the above-described steps, that is, ω ₁ = ω, Δω = 0. Even if there is distortion or frequency oscillation in the commercial power supply voltage signal, the calculation of the phase synchronization control circuit also attenuates the error caused by distortion or frequency oscillation by feedback control of the control circuit, eliminating the problem of oscillation of the phase synchronization signal be able to.

In addition, as compared with the method of using the detection circuit of the prior art and combining the comparator or the operational amplifier, the phase synchronization method of the phase synchronization circuit of the present invention directly converts the commercial power supply voltage V _S into the first function form or the second function. Convert to converted signal. Since this method is useful for increasing the response speed and also for extending the applicable frequency range, it can be used for tracking a power generation facility such as a diesel oil generator.

  Depending on the type of commercial power supply, the phase synchronization method of the phase synchronization circuit of the present invention can perform corresponding changes or adjustments. Hereinafter, reference is made to FIGS. 5 to 7 and FIGS. 8 to 10. 5 to 7 are a schematic diagram, a simulation circuit diagram, and a simulation result diagram of an embodiment when the commercial power source has a three-phase voltage, respectively, and FIGS. 8 to 10 illustrate a case where the commercial power source has a single-phase voltage, respectively. It is the schematic of one Example, a simulation circuit diagram, and a simulation result figure.

As shown in FIG. 5, the three-phase voltages of the commercial power supply are V _sa , V _sb , and V _sc , respectively, and after the abc-αβ axis conversion, the value V _m sin (ωt) of the first conversion signal S1 and the first A value V _m cos (ωt) of the two converted signal S2 is obtained. The first conversion signal S1 and the second conversion signal S2 are combined with the first synchronization signal S3 and the second synchronization signal S4, respectively, and then subtracted from each other to calculate the error value e. After the error value e passes through the proportional integrator PI, a frequency correction signal Δω is obtained.

  Subsequently, reference is made to the simulated circuit diagram and simulation results of FIGS. When setting the initial voltage value, the error (Verr) is gradually reduced by deliberately setting the phase difference between the A-phase and Sine table phase of the three-phase input voltage to 100 degrees and correcting the phase synchronization circuit. The voltage (Vin_sin) is in phase with the Sine Table (Vsin), and the frequency (Freq) is also set to 60 Hz, which is the same as the commercial power supply voltage.

As shown in FIG. 8, the commercial power supply has a single-phase voltage, and after the sampling step S111 and the delay step S112, the value V _m sin (ωt) of the first conversion signal S1 and the value of the second conversion signal S2. V _m cos (ωt) is obtained, and the first conversion signal S1 and the second conversion signal S2 are combined with the first synchronization signal S3 and the second synchronization signal S4, respectively, and then subtracted from each other. The value e is calculated. After the error value e passes through the proportional integrator PI, a frequency correction signal Δω is obtained.

Next, reference is made to the simulated circuit diagram and simulation results of FIGS. 9 and 10. When setting the initial voltage, the phase of the single-phase input voltage and the Sine table phase difference are deliberately set to 100 degrees, and the error (Verr) is gradually reduced by correcting the phase synchronization circuit. Finally, the input voltage ( Vin_sin) is in phase with Sine Table (Vsin), and the frequency (Freq) is also set to 60 Hz, which is the same as the commercial power supply voltage V _S.

  In summary, the phase synchronization method of the phase synchronization circuit of the present invention overcomes the voltage distortion and frequency change of the input commercial power supply through the above-described steps, and can achieve the effect of achieving accurate synchronization, and can also achieve high speed. It has the advantage of response and can achieve the effect of having a wide frequency range, and can be used for tracking power generation equipment such as diesel oil generators to expand the application range of inverters.

  Although the present invention has been disclosed above with the best embodiment, it will be understood by those skilled in the art that this embodiment is merely used to illustrate the present invention and limits the scope of the invention. Should not be done. It should be noted that all changes and substitutions having the same effect as this embodiment are included in the scope of the present invention. For this reason, the protection scope of the present invention conforms to the definition of the scope of claims.

Vsa, Vsb, Vsc Three-phase commercial power supply voltage 100 Grid connection system 110 Phase synchronization circuit 120 Insulation protection element 130 Voltage controller 140 Current controller 150 Sine pulse width modulation driver 160 Inverter 161 DC bus 162 MOSFET module 163 LC filter 1000 Inverter circuit 1100 Operational amplifier 1200 digital capture 1300 sine wave table _{S ZERO} zero-cross signal _{S SIN} sinusoidal signal T1 first function table T2 second function table _{V sa, V sb,} three-phase voltage of _{V sc} commercial power _{V S} utility voltage S110~S160 step
S111 Sampling process
S112 Delay process S1 First conversion signal S2 Second conversion signal S3 First synchronization signal S4 Second synchronization signal S5 Frequency correction signal

Claims (8)

A phase synchronization method for a phase synchronization circuit used in a grid connection system,
A conversion signal generating step of detecting a voltage of a commercial power source to generate a first conversion signal and a second conversion signal, wherein the first conversion signal is in a first function format, and the second conversion signal is in a second function format. When,
An error value is obtained by computing the first conversion signal, the second conversion signal, the first synchronization signal, and the second synchronization signal, and the first synchronization signal is in the second function format, An error calculating step in which a synchronization signal is in the first function form;
An error signal having the error value is input to a proportional integrator, and a frequency correction signal is acquired, and a frequency correction signal acquisition step;
First, after obtaining the adjustment frequency by adding the frequency correction signal and the original frequency, to obtain the angle signal by integrating the adjustment frequency, an angle signal acquisition step,
A value corresponding to the angle value of the angle signal is obtained by referring to the first function table and the second function table, respectively, and the value corresponding to the angle value of the angle signal in the first function table is set to the first function table. A synchronization signal generating step, wherein the value of the synchronization signal is a value corresponding to the angle value of the angle signal in the second function table;
A phase synchronization method for a phase synchronization circuit, comprising:   The first function table is a sine wave table, the second function table is a cosine wave table, and the phase difference between the phase of the first synchronization signal and the phase of the second synchronization signal The phase synchronization method of the phase synchronization circuit according to claim 1, wherein is 90 degrees. The error calculation step includes
A first product acquisition step of synthesizing values of the first conversion signal and the first synchronization signal to acquire a first product;
A second product acquisition step of synthesizing values of the second conversion signal and the second synchronization signal to acquire a second product;
An error value acquisition step of subtracting the second product from the first product and acquiring the error value;
The phase synchronization method of the phase synchronization circuit according to claim 1, comprising:   The angle signal acquisition step and the synchronization signal generation step further include an angle limiting step, and the angle limiter of the angle signal is first limited within a certain range by a range limiter. A phase synchronization method of the phase synchronization circuit described.   The commercial power supply has a three-phase voltage, and the conversion signal generation step detects the three-phase voltage of the commercial power supply to generate the first conversion signal and the second conversion signal. Item 2. A phase synchronization method for a phase synchronization circuit according to Item 1.   The commercial power supply has a single-phase voltage, and the conversion signal generation step detects the single-phase voltage of the commercial power supply to generate the first conversion signal and the second conversion signal. Item 2. A phase synchronization method for a phase synchronization circuit according to Item 1.   The phase synchronization according to claim 6, further comprising a sampling step in the conversion signal generation step, wherein the first conversion signal is generated by performing sampling on the detected voltage of the commercial power source. Circuit phase synchronization method. 8. The phase synchronization method of a phase synchronization circuit according to claim 7, further comprising a delay step in the conversion signal generation step, wherein the second conversion signal is generated by delaying the first conversion signal.

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