KR102259951B1 - Power generation system - Google Patents

Abstract

An object of the present invention is to provide a power generation system for estimating the rotational speed of the generator by calculating at least one waveform of voltage or current transmitted from the generator at the input end of the power converter, and controlling the power converter based on the expected speed. .
In order to achieve the above object, the power generation system of the present invention is a generator for generating electric energy, one end is connected to the generator, the other end is connected to the load, and converts the output power of the generator into direct current or alternating current and transmits it to the load Calculating an estimate of the rotational speed of the generator based on the output of the power conversion unit, a filter unit provided between the generator and the power conversion unit, a sensing unit measuring at least one of a voltage or a current of the filter unit, and the sensing unit and a control unit for controlling the power conversion unit based on the estimated rotation speed of the generator.

Description

Power generation system

The present invention relates to a power generation system for measuring the rotational speed of a generator using any one of a waveform period of voltage or current.

A generator is a device that converts natural energy into electrical energy to generate electricity, and includes solar power, hydroelectric power, and wind power generators. A wind power generator may be largely composed of a generator generated by a blade, a power converter that converts generated energy, and a battery that stores generated energy. The blade is rotated by the wind to convert wind energy into mechanical energy, and the rotational energy generated from the blade is converted into electrical energy through the generator, and the current of the generator is transmitted to the power converter. The power conversion unit and the control unit may convert the current of the generator into direct current or alternating current, and may store or consume energy by transferring it to a load or a battery.

At this time, the power conversion unit and control unit, which play an electrical role, rectify the input AC power, smooth it into a DC link, charge it to the battery through the power supply device, and supply the necessary electrical energy to the load, so that the system can play a role suitable for the purpose. to do it

At this time, the power conversion unit and the control unit should generate the output current command according to the strength of the wind, find the high-efficiency points of the blade and the generator through device tests in advance, and complete the torque schedule by writing the values of speed and torque in a table Then, the power conversion unit and the control unit find a torque that matches the speed according to this torque schedule, generate an output current command corresponding to this, and generate power as much as the command value.

Conventionally, a technique for measuring the rotational speed of the generator by providing a sensor for measuring the blade rotation RPM, voltage and current in a converter for converting the alternating current of the generator into a direct current is used, and the embodiment is as follows.

Referring to Korean Patent Application Laid-Open No. 10-2018-0063583, as shown in FIG. 1 , a conventional small wind power generator multiple input control system converts a three-phase AC voltage generated by the wind power generator into a direct current in the wind power generator control system. AC/DC converter circuit for converting into voltage, AC/DC converter module including a sensor circuit for measuring rotation RPM, voltage and current of the wind turbine blade, the magnitude of the DC voltage output from the AC/DC converter module A DC/DC converter module that converts a constant voltage, a brake module that includes a DUMP circuit and a brake circuit, and controls the excess of the maximum power generation amount of the wind power generator. Through the RPM, voltage and current data transmitted from the AC/DC converter module An MCU module for controlling the maximum power tracking of the wind power generator, measuring the voltage and current output from the DC/DC converter module and supplying it to the battery module, and an inverter for converting the DC voltage stored in the battery module into an AC voltage .

However, the power conversion unit and control unit for controlling the small wind power generator has a very low unit cost, high unit cost, difficult to embed a sensor with a precise function, and a method for recognizing the speed of the generator in the simplest possible way should be used. There was a problem.

In addition, depending on the distance between the generator and the power converter and the controller, an error between the voltage of the generator measured by the power converter and the voltage of the actual generator occurs, and the voltage error that occurs depending on the distance between the generator and the power converter and the controller A method for measuring the speed of the generator was required.

Republic of Korea Patent Publication No. 10-2018-0063583 (published on June 12, 2018)

The present invention has been devised to solve the above problems, calculates at least one waveform of voltage or current transmitted from the generator at the input end of the power converter to estimate the rotational speed of the generator, and based on the expected speed, the power converter An object of the present invention is to provide a power generation system that controls.

Power generation system according to an embodiment of the present invention is a generator that generates electrical energy, one end is connected to the generator, the other end is connected to the load, converting the output voltage of the generator into direct current or alternating current to deliver to the load Estimating the rotational speed of the generator based on the output of the power converter, a filter unit provided between the generator and the power converter, a sensing unit measuring at least one of a voltage or a current of the filter unit, and the sensing unit, It characterized in that it comprises a control unit for controlling the power conversion unit based on the rotation speed of the generator.

Furthermore, the generator is connected to the blade and generates power through the rotational force of the blade rotated by wind energy, the power converter is connected to the generator, and a rectifier for converting an alternating voltage into a direct current voltage, the rectifier and one end is connected, the other end is connected to the load, a converter that receives a DC voltage that is the output of the rectifier and controls at least one of a voltage or a current applied to the load, and a DC link capacitor module provided between the rectifier and the converter Including, the control unit calculates the rotation speed of the generator estimated based on at least one of the voltage or current of at least some of the branches or nodes of the filter unit, and the estimated rotation of the generator It may be characterized in that MPPT (Maximum Power Point Tracking) control is performed based on the speed.

,

인 것을 특징으로 할 수 있다.Furthermore, the generator is an alternator having an n-phase phase, and the filter unit includes an m-phase impedance circuit connected to the output of the generator, wherein,

,

It can be characterized as

,

인 것을 특징으로 할 수 있다.Furthermore,

,

It can be characterized as

Furthermore, the impedance circuit on at least a part of the m-phase impedance circuit may include at least two resistors.

Furthermore, the impedance circuit on at least a portion of the m-phase impedance circuit may include at least one of a resistor, a capacitor, and an inductor.

Furthermore, the filter unit may be characterized in that it is directly connected to the negative end of the DC link capacitor module or through an impedance.

Further, the DC link capacitor module may be characterized in that two or more capacitors are connected in series, and the filter unit is connected to the neutral point of the DC link capacitor module directly or through an impedance.

Furthermore, the control unit may be characterized in that it calculates the rotation speed of the generator based on at least one of a period, a frequency, and a phase of at least one measurement signal among the outputs of the sensing unit.

Furthermore, the control unit includes a counter that automatically increases in value at a predetermined sub-period, compares the measurement signal with a predetermined reference value, and resets the counter at the beginning of the period of the measurement signal, and the output value of the counter It may be characterized in that the rotation speed of the generator is estimated based on the .

Furthermore, the sensing unit outputs a plurality of signals, and the control unit compares the plurality of measurement signals with a predetermined reference value to reset the counter at the start time of each cycle of the plurality of measurement signals, and the output value of the counter It may be characterized in that the rotation speed of the generator is estimated based on the .

Furthermore, the control unit may measure the rotational speed of the generator using the number of counts and a predetermined time by using the following [Equation 1].

[Calculation 1]

The power generation system of the present invention can prevent the reliability of the estimate of the rotation speed of the generator from falling due to an error in the voltage measured in the DC link capacitor module by the distance between the generator and the power converter.

In addition, since the filter unit can use a filter circuit used for noise reduction in a generally used power generation system circuit, a separate configuration is not required to estimate the rotational speed of the generator, and a filter is applied to a commonly used power generation system circuit. Even if additional application is required, the structure of the filter part is simple, and there is an effect that it can be easily installed at a low cost.

1 is a flow chart of a control method of a conventional wind power generator strong wind power generation mode;
2 is a circuit diagram of a power generation system configuration of the present invention;
3 is an enlarged circuit diagram according to an embodiment of the present invention;
4 is an enlarged circuit diagram according to another embodiment of the present invention;
5 is a control flowchart according to an embodiment of the present invention;
6 is a measurement graph according to another embodiment of the present invention;
7 is a control flowchart according to another embodiment of the present invention;

Hereinafter, the technical idea of the present invention will be described in more detail using the accompanying drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Accordingly, the configuration shown in the embodiments and drawings described in the present specification is only the most preferred embodiment of the present invention and does not represent all the technical spirit of the present invention, so at the time of the present application, various It should be understood that there may be variations.

Hereinafter, the technical idea of the present invention will be described in more detail using the accompanying drawings. The accompanying drawings are only an example illustrated to describe the technical idea of the present invention in more detail, so the technical idea of the present invention is not limited to the form of the accompanying drawings.

Referring to FIG. 2 , the power generation system 100 of the present invention is a generator 200 that generates electrical energy, one end is connected to the generator 200 , the other end is connected to a load 700 , and the generator 200 ) a power conversion unit 300 for converting the output power of direct current or alternating current to the load 700 , a filter unit 400 provided between the generator 200 and the power conversion unit 300 , the Calculating an estimate of the rotational speed of the generator 200 based on the output of the sensing unit 500 and the sensing unit 500 for measuring at least one of a voltage or a current of the filter unit 400, and the estimated generator It is characterized in that it comprises a control unit 600 for controlling the power conversion unit 300 based on the rotation speed of (200).

Through the configuration as described above, the power generation system 100 of the present invention due to the error of the voltage measured in the DC link capacitor module 330 by the distance between the generator 200 and the power converter 300, It is possible to prevent the reliability of the estimate of the rotation speed of the generator 200 from being deteriorated.

In addition, since the filter unit 400 may use a filter circuit used for noise reduction in a generally used power generation system 100 circuit, a separate configuration is required to estimate the rotation speed of the generator 200 . may not

In addition, even if the filter unit 400 is to be applied to the circuit of the power generation system 100 that is generally used, the structure of the filter unit 400 is simple, so that it can be easily installed at a low cost.

In addition, according to the size of the power generation system 100 of the present invention or the load 700 to be connected, the measurement method is easy by measuring the voltage of the generator 200 to estimate the rotation speed of the generator 200, and installation It can be applied to the power generation system 100 for a purpose that can lower the unit price, and the power generation system 100 for the purpose of measuring the current of the generator 200 and estimating the rotation speed of the generator 200 to increase the measurement reliability ) can also be applied.

At this time, the generator 200 may be connected to the blade and generate power through the rotational force of the blade rotated by wind energy, and various sizes and shapes applied for wind power generation may be applied to the blade. have. In addition, the generator 200 has a unique rotational moment of inertia, and transmits the generated energy to the power converter 300 in the form of the alternating current.

In addition, the power converter 300 includes a rectifier 310 for converting an AC voltage into a DC voltage, a converter 320 for controlling at least one of a voltage or a current applied to the load 700 based on the DC voltage, and A DC link capacitor module 330 provided between the rectifier 310 and the converter 320 may be included.

The rectifier 310 is configured to convert the AC current delivered from the generator 200 into DC or AC and transmit it to the DC link capacitor, and the converter 320 transfers the DC current to the load 700 . is a configuration that

The load 700 may include a battery and is not included in the power generation system 100 of the present invention, but is connected to the power generation system 100 of the present invention and is generated by the generator 200, and the The electric energy converted by the power converter 300 may be consumed.

The DC link capacitor module is configured to receive the DC current through the rectifier 310 .

The filter unit 400 is an impedance circuit formed between the generator 200 and the power conversion unit 300 .

The sensing unit 500 is configured to measure at least one of a voltage or a current applied to the filter unit 400 , and the sensing unit 500 measures at least one of the voltage or current of the filter unit 400 . In this case, it is preferable that the impedance of the filter unit 400 is sufficiently large so that the sensing unit 500 does not measure all the voltage or current generated by the generator 200 .

The control unit 600 estimates the rotational speed of the generator 200 using the output value of the sensing unit 500, and according to the estimated rotational speed of the generator 200, By generating an output current command, the power converter 300 can output a current corresponding to the rotation speed of the generator 200 .

In addition, the control unit 600 calculates the rotation speed of the generator 200 estimated based on at least one of the voltage or current of at least some of the branches or nodes of the filter unit 400 . And, it may be characterized in that MPPT (Maximum Power Point Tracking) control based on the estimated rotation speed of the generator.

,

인 것을 특징으로 할 수 있다.In addition, the generator 200 is an alternator having an n-phase phase, and the filter unit 400 includes an m-phase impedance circuit connected to the output of the generator 200, where,

,

It can be characterized as

In this case, the generator 200 may be an alternator 200 having at least one phase or more, and the filter unit 400 may include an impedance circuit of at least one phase or more.

For example, when the generator 200 is an alternator 200 having one phase, the filter unit 400 may be formed of a one-phase impedance circuit as shown in FIG. 2 .

,

인 것을 특징으로 할 수 있다.In this case, the generator 200 may be formed as an alternator having three or more phases, and the filter unit 400 may include an impedance circuit having less than three phases. That is, the present invention

,

It can be characterized as

Referring to FIG. 3 , the generator 200 is an alternator 200 having three phases, and the filter unit 400 includes three-phase impedance circuits Z11, Z12, Z21, Z22, Z31, and Z32 in parallel. It may be characterized as being connected. At this time, each impedance circuit is composed of a first impedance circuit (Z11, Z12), a second impedance circuit (Z21, Z22), and a third impedance circuit (Z31, Z32), the first impedance circuit (Z11, Z12) , the second impedance circuits Z21 and Z22 and the third impedance circuits Z31 and Z32 are preferably connected in series.

In this case, the impedance circuit of at least a part of the m-phase impedance circuit may include at least two resistors.

In addition, all of the three-phase impedance circuits Z11, Z12, Z21, Z22, Z31, and Z32 may be formed of resistors.

That is, all of the components constituting the first impedance circuits Z11 and Z12 are resistors, the components constituting the second impedance circuits Z21 and Z22 are all resistances, and the third impedance circuits Z31 and Z32 are formed. All configurations are made of resistors.

In addition, the filter unit 400 may be characterized in that it is connected to the negative end of the DC link capacitor module 330 directly or through an impedance. This has the advantage that the connection between the filter unit 400 and the DC link capacitor module 330 is simple, and the configuration of the DC link capacitor module 330 can be made of a single capacitor, which can lower the installation cost. There are advantages.

Referring to FIG. 4 , in this case, the impedance circuit on at least a portion of the m-phase impedance circuit may include at least one of a resistor, a capacitor, and an inductor.

That is, the three-phase impedance circuits Z11, Z12, Z21, Z22, Z31, and Z32 may each include a resistor and a capacitor, and the first impedance circuits Z11 and Z12 may include a first resistor Z11 and It is composed of a first capacitor 331 (Z12), and the second impedance circuits Z21 and Z22 are composed of a second resistor Z21 and second capacitors 332 and Z22, and the third impedance circuit ( Z31 and Z32 are composed of a third resistor Z31 and a third capacitor Z32.

In addition, in the DC link capacitor module 330, two or more capacitors are connected in series, and the filter unit 400 is connected to the neutral point of the DC link capacitor module 330 directly or through an impedance. can This has an advantage that noise generated in the DC link capacitor is reduced.

Referring to FIG. 5 , the control unit 600 uses the cycle and time of any one of the voltage or current measured by the sensing unit 500 to control the generator 200 formed in the generator 200 . It may be characterized in that the rotation speed is calculated.

At this time, the measurement signal forms a waveform and has a constant cycle, the start and end of the cycle are counted as one count, and the number of counts is used for a predetermined time range determined by the control unit 600 of the generator 200. Calculate the rotation speed.

In addition, the control unit 600 uses a preset reference value to start a cycle of the measurement signal when the measurement signal is measured to be greater than or equal to the reference value, and when the measurement signal is measured to be less than the reference value, the measurement signal It may be characterized by repeating the completion of one count by ending the cycle of .

Using the reference value, when a low voltage or current is transmitted from the generator 200 to the sensing unit 500 due to the low-speed rotation of the generator 200, the effect of preventing overflow of the count there is

Referring to FIG. 5 , the control method of the power generation system 100 of the present invention will be described. The control unit 600 measures the signal of the sensing unit 500, and when the measured signal is greater than the reference value, the period to start The control unit 600 measures the period of the measurement signal, and when the measurement signal is less than the reference value, ends the period to generate one count.

The control unit 600 may measure the rotation speed of the generator 200 by generating one count in the same way as described above, and may measure the rotation speed of the generator 200 by generating a plurality of counts. .

Referring to FIG. 6 , the control unit 600 calculates the rotation speed of the generator 200 based on at least one of the period, frequency, and phase of at least one measurement signal among the outputs of the sensing unit 500 . can be characterized.

In addition, the control unit 600 includes a counter that automatically increases in value at a predetermined sub-period, compares the measurement signal with a predetermined reference value, and resets the counter at the beginning of the period of the measurement signal, and the counter It may be characterized in that the rotation speed of the generator 200 is estimated based on the output value of .

In this case, the control unit may measure the rotational speed of the generator using the number of counts and a predetermined time using the following [Equation 1].

[Calculation 1]

Freq: rotation speed of generator N: number of counts Tcount: time of counting K: coefficient according to number of poles, n: generator phase

In more detail, the control unit 600 calculates the rotation speed of the generator 200 formed in the generator 200 using the period and time of any one of the voltage or current measurement signal of the three-phase impedance circuit. It can be characterized as

6 shows a waveform when the sensing unit 500 measures the voltage of the filter unit 400 , and when the sensing unit 500 measures the current of the filter unit 400 , a different shape is obtained. It is obvious that the waveform can be represented.

In addition, the waveform of FIG. 6 is a waveform generated by deforming the Sin waveform when the sensing unit 500 senses the voltage of the filter unit 400 configured as an impedance circuit.

At this time, the measurement signal forms three waveforms, each having a constant period, and the start and end of the period are counted as one count, but the three waveforms have different start and end points, respectively, and the control unit 600 calculates the rotational speed of the generator 200 using the number of counts generated by the three-phase impedance circuit for a predetermined time range. If the rotation speed of the generator 200 is calculated using the three-phase impedance circuit as described above, there is an advantage in that a larger number of the counts can be generated for a certain time range, so that the above count can be generated using a smaller time range. The rotation speed of the generator 200 can be calculated.

At this time, the measurement signal of each of the three-phase impedance circuits forms a waveform and has a constant period, each period of the three-phase impedance circuit is included in one count, and the count of the three-phase impedance circuit during a predetermined time range determined by the control unit 600 Using the number, the rotation speed of the generator 200 is calculated.

In addition, the control unit 600 starts a cycle of each measurement signal of the three-phase impedance circuit when the measurement signal of each of the three-phase impedance circuits is measured to be greater than or equal to the reference value using a preset reference value, When the measurement signal of each of the phase impedance circuits is measured below the reference value, the cycle of the measurement signal is terminated, but whenever the measurement signal of each of the three phase impedance circuits is measured above the reference value, a timer interrupt is performed to count the previous It may be characterized by ending and starting a new count. That is, when the first signal, which is the measurement signal of the first impedance circuits Z11 and Z12 among the three-phase impedance circuits, is measured to be greater than or equal to the reference value using a preset reference value, the first period that is the period of the first signal When the second signal, which is the measurement signal of the second impedance circuits Z21 and Z22, is measured to be greater than or equal to the reference value, the first cycle is completed to complete one count and the cycle of the second signal is When the second period is started and the third signal, which is the measurement signal of the third impedance circuits Z31 and Z32, is measured to be greater than or equal to the reference value, the second period is terminated to complete one count and the third signal starting the third period, which is the period of , and when the first signal is again measured above the reference value, ending the third period to complete one count and repeating the process of starting the first period again can be characterized. As described above, through the timer interrupt, there is an advantage that a larger number of the counts can be generated for a certain time range, and the rotational speed of the generator 200 can be calculated using a smaller time range. .

Referring to FIG. 7 , the control method of the power generation system 100 to which the three-phase timer interrupt of the present invention is applied will be described. The control unit 600 measures the signal of the sensing unit 500, and the first When the signal is greater than the reference value, the first period is started. The control unit 600 measures the period of the first signal, and when the second signal is measured to be greater than or equal to the reference value, the first period is terminated and one count is generated. A period of the second signal is measured, and when the third signal is measured to be greater than or equal to the reference value, the second period is terminated to generate one count. The period of the third signal is measured, and when the first signal is again measured to be equal to or greater than the reference value, the third period is terminated to generate one count, and this process is repeated. While the count generation is repeated as described above, the control unit 600 calculates the rotational speed of the generator 200 using the number of counts generated for a certain time, and matches the calculated rotational speed of the generator 200. An output current command is generated and transmitted to the power converter 300 .

The predetermined time used to obtain the rotation speed of the generator 200 by the control unit 600 may be a time point for obtaining the rotation speed of the generator 200 from the first time point, and using a moving average, the generator ( 200), only the time range from the time of obtaining the rotation speed to before a certain range may be used.

The present invention is not limited to the above-described embodiments, and of course, various modifications can be made without departing from the gist of the present invention as claimed in the claims.

100: power generation system
200: generator
300: power conversion unit 310: rectification unit
320: converter 330: DC link capacitor module
331: first capacitor 332: second capacitor
400: filter unit 500: sensing unit
600: control unit 700: load

Claims (12)

generators that generate electrical energy;
a power conversion unit having one end connected to the generator, the other end connected to the load, and converting the output voltage of the generator into direct current or alternating current and transferring it to the load;
a filter unit provided between the generator and the power conversion unit;
a sensing unit for measuring at least one of a voltage and a current of the filter unit; and
A control unit for estimating the rotational speed of the generator based on the output of the sensing unit, and controlling the power converter based on the estimated rotational speed of the generator; includes,
The control unit,
Power generation system, characterized in that for calculating the rotational speed of the generator based on at least one of the period, frequency, and phase of at least one measurement signal of the output of the sensing unit.
The method of claim 1,
The generator is connected to the blade, and generates power through the rotational force of the blade rotated by wind energy,
The power converter,
A rectifier connected to the generator and converting an AC voltage into a DC voltage,
a converter having one end connected to the rectifier and the other end connected to a load, receiving a DC voltage output from the rectifier and controlling at least one of a voltage or a current applied to the load, and
a DC link capacitor module provided between the rectifier and the converter,
The control unit,
Calculate the rotation speed of the generator estimated based on at least one of the voltage or current of at least some of the branches or nodes of the filter unit,
Controlling MPPT (Maximum Power Point Tracking) based on the estimated rotation speed of the generator
A power generation system characterized by
The method of claim 2,
The generator is an alternator having an n-phase phase,
The filter unit,
It includes an m-phase impedance circuit connected to the output of the generator,
here,

,

being
A power generation system characterized by
The method of claim 3,

,

being
A power generation system characterized by
The method of claim 3
The impedance circuit of at least a part of the m-phase impedance circuit comprises:
A power generation system comprising at least two resistors.
The method of claim 3,
The impedance circuit of at least a part of the m-phase impedance circuit comprises:
A power generation system comprising at least one of a resistor, a capacitor, and an inductor.
According to claim 2, wherein the filter unit,
Power generation system, characterized in that connected to the negative terminal of the DC link capacitor module directly or through an impedance.
The method of claim 2,
In the DC link capacitor module, two or more capacitors are connected in series,
The filter unit is a power generation system, characterized in that connected to the neutral point of the DC link capacitor module directly or through an impedance.
delete According to claim 1, wherein the control unit,
and a counter whose value is automatically incremented at a predetermined sub-period;
Comparing the measurement signal with a predetermined reference value and resetting the counter at the beginning of the cycle of the measurement signal,
estimating the rotation speed of the generator based on the output value of the counter
A power generation system characterized by
The method of claim 10,
The sensing unit outputs a plurality of signals,
The control unit,
Comparing the plurality of measurement signals with a predetermined reference value and resetting the counter at the beginning of each cycle of the plurality of measurement signals,
estimating the rotation speed of the generator based on the output value of the counter
A power generation system characterized by
The method of claim 11,
The control unit is a power generation system, characterized in that by using the following [Equation 1] to measure the rotational speed of the generator using the number of counts and a predetermined time.
[Formula 1]

Freq: rotation speed of generator N: number of counts Tcount: time of counting K: coefficient according to number of poles, n: generator phase

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