KR102355397B1 - Forced commutation control apparatus for torque ripple reduction of turbine start-up equipment, Method thereof, and Computer readable medium storage having the same - Google Patents

Abstract

A forced current control system for a turbine starting device is disclosed. The forced current control system of the turbine starting device includes a first converter in which a plurality of first switching elements are disposed, an inverter connected to the first converter and in which a plurality of second switching elements are disposed, and an input applied to the first converter A control block that senses a voltage and an output voltage output from the inverter to execute forced current control for reducing torque ripple when switching the second switching element, and a synchronous generator operated by the forced current control characterized.

Description

Forced current control system for a turbine starting device for reducing torque ripple, a control method thereof, and a computer-readable storage medium storing the method readable medium storage having the same}

The present invention relates to a gas turbine power generation technology, and more particularly, to a system and method for controlling a forced current of a turbine starting device for reducing torque ripple.

The gas turbine generator for the power generation industry uses the Brayton cycle power generation method in which a turbine, a compressor, and a synchronous generator are uniaxial. To obtain the rotational force of the gas turbine required in this power generation method, it was initially to use a torque converter that directly drives the turbine rotor. However, with the rapid development of power conversion technology from the 1990s, the technology of driving a large synchronous generator in the form of a motor has been applied, and continuous technological development is continuing.

In a large-capacity (several hundred MW) gas turbine synchronous generator, unlike a steam turbine generator, the compressed air and liquefied natural gas (LNG) fuel can be mixed and burned only when the gas turbine rotor composed of a compressor and a single body rotates at a certain speed or higher.

It is known that the operation characteristics of a general gas turbine generator are capable of igniting LNG fuel and maintaining combustion when the speed is increased to about 1,000 rpm based on the rated speed of 3600 rpm. Then, the speed characteristic is determined according to the combustion gas by the amount of fuel supplied and the rotational force of the synchronous generator by the starting device.

The role of the starting device is up to about 90% of the rated speed, and up to the rated speed is reached by the magnetic force of the combustion gas. As a starting device for initial starting of a gas turbine generator, a stationary load current inverter system (hereinafter, referred to as a starting device) using a thyristor power semiconductor device has been commercialized and operated in many cases.

The thyristor OFF method, which is the power conversion element of the turbine starting device, must apply a reverse voltage enough to reverse the current flow between the anode and the cathode of the switch, or prevent the current from flowing in the element, unlike a general power semiconductor element.

However, in the case of a synchronous generator (ie, a synchronous motor) that is initially started from a stop state, it is difficult to turn off the inverter thyristor connected to the synchronous generator side because the back electromotive voltage induced at low speed is small, and it is difficult to switch to the next switch. Therefore, in this section, the thyristor ON state of the inverter is forcibly turned OFF by forcibly setting the current supplied from the converter to 0 [A] during switching. In the case of forced current control, the DC link current is set to 0 [A], and the converter proportional integral controller fires so that the reverse voltage is applied.

However, the power plant turbine starting device is a device for initially increasing the speed of the synchronous generator, and increases the speed from a stop to a constant speed. When operated at low speed, forced current control is used due to the characteristics of the thyristor element, but the section in which the DC reactor current becomes 0 [A] is quite long, resulting in torque ripple.

At this time, the current rapidly becomes 0 [A] due to the reverse voltage, creating a condition for the inverter to be switched to the next switch. As a result of testing the existing technology, there was no problem in inverter switching, but the disadvantage of lengthening the 0[A] section was found.

In addition, in order to shorten this section, the tuning value of the proportional integral controller was set to speed up the response characteristics, but an overshoot value occurred, and this technology also played a role in generating the torque ripple of the synchronous generator.

1. Korea Patent No. 10-1624845 (Registration Date: 2016.05.23) 2. Korea Patent Publication No. 10-2009-0074265 3. Japanese Patent No. 4157218 (2008.07.18)

In order to solve the problem according to the above background art, the present invention is a forced turbine starting device capable of inverter switching without lengthening the section for forcibly reducing the current supplied from the converter to zero (0 [A]) during switching switching. It is an object to provide a current control system and method.

Another object of the present invention is to provide a system and method for controlling a forced current of a turbine starting device that speed up response characteristics without generating torque ripple and/or overshoot of the synchronous generator.

The present invention provides a forced current control system of a turbine starting device capable of inverter switching without lengthening the section for forcibly reducing the current supplied from the converter to 0 [A] during switching switching in order to achieve the task presented above. .

The forced current control system of the turbine starting device,

a first converter in which a plurality of first switching elements are disposed;

an inverter connected to the first converter and arranged with a plurality of second switching elements;

a control block sensing an input voltage applied to the first converter and an output voltage output from the inverter to execute forced current control for reducing torque ripple when switching the second switching element; and

and a synchronous generator operated by the forced current control.

In addition, the forced current control sets the output value of the first converter to a preset maximum (-) output voltage value during the forced current of the inverter, and then returns the inverter to an initial value preset by a reset signal during recovery. It is characterized by using the current output voltage value of .

Further, the control block includes a current controller that executes the forced current control.

In this case, the current controller may include: a low-pass filter for filtering the induced voltage signal by the counter electromotive force of the synchronous generator; a zero point identifier for finding and identifying a zero point after separating the filtered induced voltage signal from the three-phase voltage waveform; and a forced pulse logic signal generator configured to generate a forced pulse logic signal to generate the reset signal according to the zero point.

In addition, the forced pulse logic signal is a signal for resetting the initial value of the current proportional integral controller.

In addition, the initial value is a variable initial value, and in order to calculate the variable initial value, the terminal voltage of the synchronous generator is calculated as a rectified rms line voltage.

In addition, the variable initial value is calculated by using the rms line voltage of the first converter as well.

에 의해 산출되는 것을 특징으로 한다.In addition, the variable initial value is

It is characterized in that it is calculated by

In addition, the variable initial value is characterized in that the DC reactor current is 0 [A] when the difference between the DC link voltage of the converter and the DC link voltage of the inverter is zero.

In addition, the current proportional integration controller is characterized in that to generate a reverse voltage by setting the firing angle control signal to 180 ° in order to quickly make the DC reactor current 0 [A].

In addition, the current proportional integration controller is characterized by applying an initial value proportional to the terminal voltage of the synchronous generator to reduce the width of the DC current zero section.

In addition, the low-pass filter is characterized in that the high-frequency noise is removed but a filter in which the frequency of the material point is changed according to the frequency so that there is no phase delay.

In addition, the forced current control is characterized in that only the initial 10% of the rated speed is performed.

In addition, the second switching element is characterized in that the thyristor.

On the other hand, another embodiment of the present invention comprises the steps of: (a) applying an input voltage to a first converter in which a plurality of first switching elements are disposed; (b) outputting an output voltage from an inverter connected to the first converter and in which a plurality of second switching elements are disposed; (c) detecting the input voltage and the output voltage by a control block, and executing forced current control for reducing torque ripple when switching the second switching element; and (c) operating a synchronous generator to control the forced current.

In this case, the step (c) may include: filtering, by the low-pass filter of the current controller, the induced voltage signal by the counter electromotive force of the synchronous generator; After the zero point identifier isolates the filtered induced voltage signal from the voltage waveform between three phases, finding and identifying the zero point; and generating, by the forced pulse logic signal generator, a forced pulse logic signal to generate the reset signal according to the zero point.

On the other hand, another embodiment of the present invention provides a computer-readable storage medium storing a program code for executing the forced current control method of the turbine starting device for torque ripple reduction described above.

According to the present invention, it is possible to make the forced current 0 [A] section as short as possible.

In addition, as another effect of the present invention, by applying a variable initial value to the forced current control, the 0[A] section is considerably shortened and the torque ripple is also reduced.

In addition, as another effect of the present invention, the forced current control part is used at 10% or less of the rated speed, and at this time, the speed is gradually increased. It is possible to achieve the effect of shortening the time, and in addition, it is possible to reduce the electricity cost used by the large-capacity starting device.

1 is a simplified diagram of a general starting device of a gas turbine.
FIG. 2 is a power flow diagram of the starting device of the gas turbine shown in FIG. 1 .
3 is an equivalent circuit diagram of the starting device of the gas turbine shown in FIG. 1 .
4 is a waveform diagram of a DC reactor current and a synchronous generator voltage during forced current control of a general starting device.
5 is a conceptual diagram illustrating the principle of forced current control of a general starting device.
6 is a conceptual diagram for forcibly switching off the switching element by setting the conduction current of the switching element to “0” in FIG. 5 .
FIG. 7 is a conceptual diagram for forcibly switching off the switching element by setting the conduction current of the switching element to “0” in the state of FIG. 6 .
8 is a pulse diagram illustrating a DC reactor current and a synchronous generator phase current in forced current control according to an embodiment of the present invention.
9 is a waveform diagram of a forced current controller reset signal generation for reducing torque ripple according to an embodiment of the present invention.
10 is a block diagram of a forced current control system of a turbine starting device for reducing torque ripple according to an embodiment of the present invention.
11 is a DC reactor current waveform before and after applying a torque ripple reduction forced current control logic according to an embodiment of the present invention.
12 is a flowchart illustrating a control sequence of a forced current starting device for reducing torque ripple according to an embodiment of the present invention.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing each figure, like reference numerals are used for like elements. Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The term “and/or” includes a combination of a plurality of related listed items or any of a plurality of related listed items.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. shouldn't

Hereinafter, a system and method for controlling a forced current of a turbine starting device for reducing torque ripple according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

It was noted that in an embodiment of the present invention, the DC reactor current value is determined by the voltage difference between the converter and the inverter. In the case of forced current, the converter proportional-integral controller reaches the reference set signal value faster by using the current inverter output voltage value as the initial value by the reset signal in the process of returning the converter output value to the maximum (-) value. Confirmed. Accordingly, the initial value is changed in real time as the terminal voltage rises when the synchronous generator (SM: Synchronous motor) increases the rotation speed.

1 is a simplified diagram of a general starting device of a gas turbine. Referring to FIG. 1 , the starting device 100 rotates a stationary synchronous generator (ie, a synchronous motor) 120 by interaction between a rotor and a stator, and an optimal switching element 11 to drive it with maximum torque. is controlled by the switching sequence of To this end, the starting device 100 includes an input transformer 101 for a starting device, a first converter 111 receiving power from the input transformer 101 for the starting device, a first converter 111 and a DC (Direct Current) ) The inverter 113 connected to the reactor 112, the excitation transformer 102, the second converter 115 receiving the excitation current Ie from the excitation transformer 102, to produce power or to start the initial operation It may be composed of a synchronous generator 120 to perform, a turbine 130 that rotates the synchronous generator 120 or is initially started by the synchronous generator 120 . That is, the power generated from the synchronous generator 120 is converted into a DC current Idc through the inverter 113 and supplied to the first converter 111 .

The switching element 11 may be a thyristor, but is not limited thereto, and a semiconductor switching element such as a Field Effect Transistor (FET), a Metal Oxide Semiconductor FET (MOSFET), an Insulated Gate Bipolar Mode Transistor (IGBT), and a power rectifying diode. , GTO (Gate Turn-Off) thyristor, TRIAC (Triode for alternating current), SCR (Silicon Controlled Rectifier), IC (Integrated Circuit) circuit and the like may be used. In particular, in the case of a semiconductor device, a bipolar device, a power MOSFET (Metal Oxide Silicon Field Effect Transistor) device, etc. may be used. The power MOSFET device has a double-diffused metal oxide semiconductor (DMOS) structure unlike general MOSFETs due to high voltage and high current operation.

When the synchronous generator 120 is a large synchronous generator of a different excitation method, a constant current must be supplied to generate magnetic flux between the stator (not shown) and the rotor (not shown). , direct current is supplied to the rotor. The turbine 130 may be a steam turbine, a hydro turbine, a thermal power turbine, or the like.

Several kA of current is injected to give a high starting torque to the synchronous generator 120 due to the characteristics of the tens of MW starting device, but a lot of torque ripple occurs in the forced current during low-speed switching, so that the turbine 130 vibrates and/or Noise is occurring. In the process of making the converter current 0 [A] in the case of forced current, the converter voltage reaches the maximum (-) voltage and then in the process of returning again, 0 [A] due to the delay until the steady current of the proportional integral controller (not shown) is reached. As the current section becomes longer, a ripple of the current occurs, and this ripple is proportional to the torque, causing a lot of vibration at low speed.

In an embodiment of the present invention, by applying an initial value proportional to the synchronous generator terminal voltage to a proportional integral controller (not shown) during forced current, the DC reactor current 0 [A] section is minimized to minimize the vibration of the synchronous generator 120 . suppressed to the maximum. Therefore, when the turbine 130 is started, it is possible to reduce bearing damage due to vibration, and by making the entire forced current section small, it is also possible to shorten the starting time of the turbine 130 .

FIG. 2 is a power flow diagram of the starting device of the gas turbine shown in FIG. 1 . Referring to FIG. 2 , the starting device may largely include a converter 111 , a DC reactor 112 , an inverter 113 , and the like. A DC current Idc flows in the DC reactor 112 by the difference between the converter voltage Vd_cov and the inverter voltage Vd_inv, and the torque value transmitted to the synchronous generator 120 is also determined according to the amount. The line voltage applied to the converter 111 (ie, the voltage across both ends) is Vrs, and the line voltage output to the inverter 113 is Vab. In addition, the power in the converter 111 is as follows.

FIG. 3 is an equivalent circuit diagram of a starting device of the turbine 130 shown in FIG. 1 . Looking at the equivalent circuit of the starting device shown in Fig. 3, the output voltage of the converter 111 is the maximum (+)1.35Vrs ~ (-)1.35Vrs, and the inverter 113 is also (+)1.35Vab ~(-) It becomes 1.35Vab. However, in the forced current control, the inverter 113 performs control with a low voltage and a phase value β = 180 in order to improve the power factor. In FIG. 3, “Z _dc ” denotes a direct current impedance, and α becomes a phase value opposite to β when the maximum torque control is performed. Therefore, when the phase value β = 180, α = 0 for control.

4 is a waveform diagram of a DC reactor current and a synchronous generator voltage during forced current control of a general starting device. Referring to FIG. 4 , an ideal DC reactor current (Idc), a synchronous generator terminal voltage (Va), and a current waveform (Ia) are shown when the starting device is forced current. In order to save energy, the starting device should be operated with an optimal torque for increasing the speed of the synchronous generator 120 .

5 is a conceptual diagram illustrating the principle of forced current control of a general starting device. Referring to FIG. 5, in the forced current control, the firing angle of the inverter on the synchronous generator 120 side is 180°, and when the field current is not controlled by a field weakening for maximum torque, constant current control is performed. Therefore, a permanent magnet having a constant magnetic flux can be expressed in the form The synchronous generator torque is determined by the magnitude of the stator flux and rotor flux, and the flux angle.

Since the magnitudes of the stator flux and the rotor flux are controlled constant, it is best to set the θ value to about 90° in order to generate the maximum torque. However, since the switching element pairs (T4 and T1, T6 and T3, T2 and T5) are current at intervals of 60°, it is optimal to operate at 120° to 90° to 60° in order to maximize the average torque. Va, Vb and Vc represent the synchronous generator terminal voltage Fig. 5 shows that when the rotor position is at 30° based on the terminal voltage Va, the switching elements 3 and 4 (T3, T4) are It indicates that it should be switched on and rotate in a counterclockwise direction.

Here, Tm is the optimal torque, K is an integer value, Ψs is the stator flux, Ψr is the rotor flux, and θ is the angle between the stator flux and the rotor flux.

6 is a conceptual diagram of forcibly switched off by setting the switching element conduction current (for example, when a thyristor is used as a switching element) in FIG. 5 to "0", and FIG. It is a conceptual diagram of forcibly switching off by setting the switching element conduction current to "0". 6 and 7 illustrate the principle of forced current control for the initial start of the synchronous generator 120 .

First, referring to FIG. 6 , in a state in which an excitation current is applied by the second converter ( 115 in FIG. 1 ), the rotor generates a magnetic flux Ψr, and the inverter 113 operates fourth and fifth to generate maximum torque. The switching elements T4 and T5 are switched to generate a stator magnetic flux ?s to rotate. In the rotational state of the rotor according to FIG. 6, referring to FIG. 7, the fourth and fifth switching elements T4 and T5 must be turned off in order to flow current to the next inverter switch pair. Turn OFF the current (Idc) to 0[A]. At this time, if the 0[A] section is long, the torque ripple is severely generated.

8 is a pulse diagram expressing a DC reactor current (Idc) and a synchronous generator phase current (Ia, Ib, Ic) in forced current control. Referring to FIG. 8 , in order to make the DC reactor current (Idc) 0 [A] in the forced current control, the converter proportional integral controller instantaneously adjusts the firing angle so that the output becomes the maximum reverse voltage.

The DC reactor current is reduced according to the characteristics of the thyristor, through which current flows in only one direction, and the current flowing through the thyristor of the inverter 113 on the synchronous generator side also becomes 0 [A], so no torque is generated and the machine of the synchronous generator 113 is There is a section that rotates with negative inertia. This forced current section is up to about 10% of the initial rated speed. In FIG. 8, it can be seen that the firing angle of the converter 113 is changed at intervals of about 60° according to the position of the rotor to make the inverter-side thyristor current 0 [A].

9 is a waveform diagram of a forced current controller reset signal generation for torque ripple reduction. Referring to FIG. 9 , the synchronous generator terminal voltages Va, Vb, and Vc are made of line voltages Vac, Vba, and Vcb, and these signals are compared with a “0” signal. The signal is made with the initial synchronous generator voltage waveform, and a special filter is required because it contains a lot of high frequency.

In order to control the maximum torque, the voltage phase is important. In order to prevent delay depending on the filter, the main parameter of the filter is changed linearly as the frequency increases, and a different method is used in which the node frequency is moved.

Using a waveform close to a sine wave with reduced high frequency to the maximum, each becomes a square wave 910, and by sensing the rising and falling signals of the square wave, it maintains ON only for the time desired by the user and returns to the input signal again. makes These signals have a reset signal 920 in the form of six square pulses per cycle. In other words, the reset signal 920 is generated at the intersection 911 where two of the three-phase voltage waveforms intersect. This waveform is set in advance by programming from an actual forced pulse logic signal generator (not shown) and is output. In FIG. 9, ωt represents a phase.

10 is a block diagram of a forced current control system 1000 of a turbine starting device for reducing torque ripple according to an embodiment of the present invention. 10, the forced current control system 1000, the control block 1001 for controlling the synchronous generator 120, the first converter 111 and the inverter 113 for applying a pulse signal to each of the first and The second pulse logic 1000-1 and 1000-2 may be included. The control block 1001 may include a current controller 1001 and a speed controller 1001-2 connected in cascade with the current controller 1001-1.

After the starting device detects the position of the rotor and starts firing on the switching elements of the converter 111 and the inverter 113 for increasing the maximum torque, the synchronous generator 120 rotates slowly.

At this time, an induced voltage is generated by the counter electromotive force of the synchronous generator 120 . This induced voltage signal passes through the second sensor 1080 - 2 and is input to the low pass filter 1011 which is changed according to the frequency. As the second sensor 1080-2, a potential transformer (PT) or the like may be used.

In addition, the low-pass filter 1011 is a filter in which the node frequency is changed according to the frequency, and has an advantage that high-frequency noise is removed according to the frequency change, but there is no phase delay.

The zero point identifier 1012 separates the filtered induced voltage signal into a three-phase line voltage waveform to create the reset signal 920 shown in FIG. It performs the function of finding and identifying

The forced pulse logic signal generator 1013 creates a forced pulse logic signal by finding the identified zero point. This forced pulse logic signal is used as an initial value reset signal of the current proportional integral controller 1016 .

The variable initial value calculating unit 1015 rectifies the terminal voltage Vabc of the synchronous generator with the second rectifier 1014-2 to calculate the variable initial value when the initial value of the current proportional integral controller 1016 is reset. Calculate with rms voltage.

At this time, the line-to-line voltage rms of the first converter 111 is also used as an input to calculate a variable initial value. That is, the applied voltage Vrst is sensed by the first sensor 1080 - 1 and calculated as an effective value of the line voltage of the first converter 111 , which is rectified by the first rectifier 1080 - 1 . As the first and second sensors 1080-1 and 1080-2, a potential transformer (PT) or the like may be used.

Variable initial value operation is defined as follows.

Here, V _{d_con} represents the output voltage of the converter.

Here, V _{d_inv} represents the output voltage of the inverter.

Here, the _{initial value} of α is the firing angle, which is the initial control value of the forced current.

The variable initial value calculation is as in Equation 6 above because the DC reactor current is 0 [A] when the difference between the DC link voltage of the first converter 111 and the DC link voltage of the inverter 113 is “0”. The forced current proportional integration controller 1016 of the converter sets the firing angle control signal to 180° in order to quickly bring the DC reactor current to 0 [A] to generate a reverse voltage.

And, in Equation 6, the firing angle of the inverter becomes (-1) because 180° is set to maximize the power factor. Since the following forced current initial control value is the firing angle (α) of the converter, the variable initial value can be obtained as in Equation (7).

The first pulse logic unit 1000 - 1 and the second pulse logic unit 1000 - 2 use the output value of the current proportional integral controller 1016 to apply pulse signals to the first converter 111 and the inverter 113 . to create A phase locked loop (PLL) 1090 generates an output signal whose frequency is kept constant with respect to the applied voltage Vrst sensed by the first sensor 1080-1 to generate a first pulse logic unit ( 1000-1).

The meter 1070 senses the applied current irst applied to the first converter 111 , the applied current is rectified by the third rectifier 1014-3 and input to the second subtractor 1042 .

Meanwhile, the speed calculator 1020 of the speed controller 1001 - 2 calculates the current rotation speed Nx of the synchronous generator 120 . The current rotation speed Nx may be calculated using a voltage applied to the synchronous generator 120 . That is, it is possible to calculate using the relational expression between the number of rotations and the voltage.

This current rotation speed Nx is provided to the low-pass filter 1011 , the sequence control logic unit 1030 , the second subtractor 1041 , the limiter 1060 , and the like.

When the sequence control logic unit 1030 receives the current rotation speed Nx, it controls the speed reference signal 1040 to output the reference rotation speed Nw preset by the user or by programming.

The second subtractor 1041 performs an operation of subtracting the current rotation speed Nx from the reference rotation speed Nw and transmits the difference value to the proportional integration controller 1050 .

The limiter 1060 limits the current flowing through the reactor according to the speed, and this value becomes the current controller reference signal and is proportional to the torque value.

The second subtractor 1042 subtracts the calculated applied current idw from the rectified current applied current idx and transfers the difference current to the current proportional integration controller 1016 .

The term “…unit” described in the drawings means a unit that processes at least one function or operation, which may be implemented in software and/or hardware. In hardware implementation, application specific integrated circuit (ASIC), digital signal processing (DSP), programmable logic device (PLD), field programmable gate array (FPGA), processor, microprocessor, other It may be implemented as an electronic unit or a combination thereof. In software implementation, software component (element), object-oriented software component component, class component component and task component component, process, function, attribute, procedure, subroutine, segment of program code, driver, firmware, microcode, data , databases, data structures, tables, arrays, and variables. Software, data, etc. may be stored in a memory and executed by a processor. The memory or processor may employ various means well known to those skilled in the art.

11 is a DC reactor current waveform before and after applying a torque ripple reduction forced current control logic according to an embodiment of the present invention. Referring to FIG. 11 , the torque ripple is proportional to the current waveform 1120 . Therefore, in order to be ideal, the section in which the current becomes 0 [A] should be reduced as much as possible. If the variable initial value is not applied after the current controller 1001-1 generates a reverse voltage to 0 [A] for the forced current, it takes time for the current controller 1001-1 to rise from the minimum value to a constant current value, whereas the variable Since the output signal 1110 of the current controller 1001-1 to which the initial value is applied is instantaneously increased, the output signal 1110 of the current proportional integral controller 1016 is adjusted after the current proportional integration controller 1016 rises, so the DC current zero section (1130) can be minimized. The DC current zero section 1130 refers to a section in which the current becomes O[A].

12 is a flowchart illustrating a control sequence of a forced current in a starting device for reducing torque ripple according to an embodiment of the present invention. Referring to FIG. 12 , when starting for the first time, forced current control is started (step S1210). When the synchronous generator 120 rotates, the terminal voltage of the synchronous generator is input, and this signal is divided into two for calculating the effective value and the nodal frequency shifting low-pass filter that varies according to the frequency (steps S1230 and S1240).

In the case of the first of the two branches, in order to generate a reset signal of the current controller (1001-1 in FIG. 10), a low-pass filter (1011 in FIG. 10) that is variable in frequency for noise removal is used first. The low-pass filter 1011 has a characteristic that the filter parameter is changed according to an increase in frequency to remove high-frequency noise from the terminal voltage signal and the phase is not delayed (step S1231).

Thereafter, after making a square waveform with the zero point identifier 1012 of the three-phase voltage, the forced pulse logic signal generator 1013 creates a forced pulse logic signal that is turned on for a predetermined time. The application of the initial value of the current proportional integral controller 1016 is determined by this signal (steps S1233 and S1235).

In the case of the second branch, the rms value is calculated as the line voltage of the synchronous generator (step S1240). As the speed of the line voltage of the synchronous generator increases, if the excitation current is constant, the line voltage effective value increases. When the variable signal and the rms line voltage of the converter are applied, the initial value is determined by the above equation (steps S1201 and S1241). Although the formula is simple, the 0[A] section of current can be significantly reduced.

Lastly, when the speed of the synchronous generator is more than 10%, the forced current control and application of the initial value are not necessary because the voltage of the synchronous generator is high enough to turn off the thyristor.

In addition, the steps of the method or algorithm described in relation to the embodiments disclosed herein are implemented in the form of program instructions that can be executed through various computer means such as a microprocessor, a processor, a CPU (Central Processing Unit), etc. It can be recorded on any available medium. The computer-readable medium may include program (instructions) codes, data files, data structures, etc. alone or in combination.

The program (instructions) code recorded on the medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the art of computer software. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs, DVDs, Blu-rays, and the like, and ROM, RAM ( A semiconductor memory device specially configured to store and execute program (instruction) code such as RAM), flash memory, and the like may be included.

Here, examples of the program (instruction) code include high-level language codes that can be executed by a computer using an interpreter or the like as well as machine language codes such as those generated by a compiler. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

11: switching element
100: starting device
101: starter input transformer
102: excitation transformer
111: first converter
112: DC current reactor
115: second converter
120: synchronous generator
130: turbine

Claims (20)

a first converter 111 in which a plurality of first switching elements 11 are disposed;
an inverter 113 connected to the first converter 111 and in which a plurality of second switching elements 11 are disposed;
Control for executing forced current control for reducing torque ripple when switching of the second switching element 11 by sensing the input voltage applied to the first converter 111 and the output voltage output from the inverter 113 block 1001; and
It includes; a synchronous generator 120 operating by the forced current control.
In the forced current control, the output value of the first converter 111 is set to a preset maximum (-) output voltage value during the forced current of the inverter 113 and is returned in advance by a reset signal 920 during recovery. Forced current control system of a turbine starting device for reducing torque ripple, characterized in that using the current output voltage value of the inverter (113) as the set initial value.
delete The method of claim 1,
The control block 1001 includes a current controller 1001-1 that executes the forced current control,
The current controller 1001-1,
a low-pass filter 1011 for filtering the induced voltage signal by the counter electromotive force of the synchronous generator 120;
a zero point identifier 1012 for separating the filtered induced voltage signal from the three-phase voltage waveform and then finding and identifying a zero point; and
Forced pulse logic signal generator (1013) for generating a forced pulse logic signal to generate the reset signal according to the zero point; Forced current control system of a turbine starting device for reducing torque ripple comprising a.
4. The method of claim 3,
The forced pulse logic signal is a forced current control system of a turbine starting device for reducing torque ripple, characterized in that it is a signal for resetting the initial value of the current proportional integral controller (1016).
5. The method of claim 4,
The initial value is a variable initial value, and in order to calculate the variable initial value, the terminal voltage of the synchronous generator 120 is a forced current of a turbine starting device for reducing torque ripple, characterized in that calculated as a rectified line-to-line voltage effective value control system.
6. The method of claim 5,
The variable initial value is a forced current control system of a turbine starting device for reducing torque ripple, characterized in that the calculation is also used together with the line voltage effective value of the first converter (111).
7. The method of claim 6,
The variable initial value is the equation

Forced current control system of the turbine starting device for torque ripple reduction, characterized in that calculated by.
6. The method of claim 5,
The variable initial value is a forced current control system of a turbine starting device for reducing torque ripple, characterized in that the DC reactor current is 0 [A] when the difference between the DC link voltage of the converter and the DC link voltage of the inverter is zero.
5. The method of claim 4,
The current proportional integral controller 1016 is a forcible current of a turbine starting device for reducing torque ripple, characterized in that it generates a reverse voltage by setting the firing angle control signal to 180 ° in order to quickly make the DC reactor current 0 [A] control system.
10. The method of claim 9,
The current proportional integral controller 1016 applies an initial value proportional to the terminal voltage of the synchronous generator 120 in order to reduce the width of the DC current zero section 1130. A turbine starting device for reducing torque ripple of forced current control system.
4. The method of claim 3,
The low-pass filter 1011 is a forced current control system for a turbine starting device for reducing torque ripple, characterized in that the high-frequency noise is removed, but the particle frequency is changed according to the frequency so that there is no phase delay.
The method of claim 1,
The forced current control is a forced current control system for a turbine starting device for reducing torque ripple, characterized in that performed only up to the initial 10% of the rated speed.
The method of claim 1,
The second switching element is a forced current control system of a turbine starting device for reducing torque ripple, characterized in that the thyristor.
(a) applying an input voltage to a first converter 111 in which a plurality of first switching elements 11 are disposed;
(b) outputting an output voltage from an inverter 113 connected to the first converter 111 and in which a plurality of second switching elements 11 are disposed;
(c) the control block 1001 senses the input voltage and the output voltage, and performs forced current control for reducing torque ripple when switching the second switching element; and
(c) operating the generator 120 synchronously to the forced current control, wherein the forced current control sets the output value of the first converter 111 when the forced current of the inverter 113 is set in advance. Turbine start for torque ripple reduction, characterized in that the current output voltage value of the inverter 113 is used as the initial value preset by the reset signal 920 during the return after returning to the (-) output voltage value of How to control the forced current of the device.
delete 15. The method of claim 14,
Step (c) is,
filtering, by the low-pass filter 1011 of the current controller 1001-1, the induced voltage signal due to the back electromotive force of the synchronous generator 120;
The zero point identifier 1012 separates the filtered induced voltage signal from the voltage waveform between three phases and then finds and identifies the zero point; and
Forced pulse logic signal generator (1013) generating a forced pulse logic signal to generate the reset signal according to the zero point; Forced current control method of a turbine starting device for reducing torque ripple comprising a.
17. The method of claim 16,
The forced pulse logic signal is a forced current control method of a turbine starting device for reducing torque ripple, characterized in that the signal for resetting the initial value of the current proportional integral controller (1016).
15. The method of claim 14,
The forced current control is a forced current control method of a turbine starting device for reducing torque ripple, characterized in that performed only up to the initial 10% of the rated speed.
15. The method of claim 14,
The second switching element is a forced current control method of a turbine starting device for reducing torque ripple, characterized in that the thyristor.
[Claim 20] A computer-readable storage medium storing a program code for executing the method for controlling a forced current of a turbine starting device for reducing torque ripple according to any one of claims 14, 16 to 19.

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