KR200307524Y1 - Control device of parallel operative generator - Google Patents

Abstract

The present invention relates to a device for controlling and protecting generators in parallel operation, and more particularly, functions such as generator synchronization control device, effective / invalid load control device, overcurrent / overvoltage meter, etc. required for parallel operation of a plurality of generators. The present invention relates to a parallel operation generator control device implemented with one microprocessor. In order to achieve the object of the present invention, the present invention converts various measured values into digital values so that they can be integrally computed and controlled by a single microprocessor so that the various output signals drive an adjusting device such as an external governor and a voltage regulator. Characterized in that.

Description

Parallel operation generator control device {CONTROL DEVICE OF PARALLEL OPERATIVE GENERATOR}

The present invention relates to a device for controlling and protecting generators in parallel operation, and more particularly, functions such as generator synchronization control device, effective / invalid load control device, overcurrent / overvoltage meter, etc. required for parallel operation of a plurality of generators. The present invention relates to a parallel operation generator control device implemented with one microprocessor.

When the generator is used only for emergency at the time of commercial power outage, not at ordinary time, a simple operation technique of operating the generator at the time of commercial power outage was used. Recently, however, it is generally used for constant use by connecting several generators in parallel in order to provide a uniform and optimal power supply by supplementing insufficient power against fluctuations in load.

1 is a view showing a conventional method for driving a plurality of generators in parallel and the various devices required for this.

Referring to FIG. 1, three generators 101, 102, 103 are provided to provide a generation voltage to the reference power bus 100, and the generators are provided with the magnitude, phase, and frequency of the generation voltages of the respective generators 101, 102, 103. Synchronizers 151, 152, 153 for synchronizing to the main power 100 voltage, load regulators 141, 142, 143 for regulating the effective and reactive load sharing of the respective generators 101, 102, 103, the existing power bus 100, and each generation voltage. Voltage, current, and power meters (161, 162, 163) measured and provided to the synchronizer and the load regulator and the like are compared to the reference value, and various instruments (171, 172, 173) for measuring the over current, over voltage, reverse power is connected to each generator.

In addition, each generator (101, 102, 103) and the corresponding engine (111, 112, 113), respectively, an automatic voltage regulator (AVR) (131, 132, 133) and each engine that receives the output from the load regulators (141, 142, 143) to control the field voltage of each generator Engine governors 121, 122, and 123 that control the frequency of each power generation voltage by adjusting the rotational speeds of the 111, 112, and 113 are connected.

In order to operate a plurality of generators in parallel, a large number of devices are required, and each of these devices requires separate installations and adjustments, and thus it is expensive and difficult to manage, and frequent failures are caused by increased accessories. And there is a problem of difficulty in maintenance in this regard.

Accordingly, an object of the present invention is to digitalize by commonizing the measured values required for parallel operation control devices of various generators to solve the above-mentioned problems, and accordingly, various functions are implemented using a microprocessor, so that the cost is low and the failure rate is low. The present invention provides a parallel operation control device that is easy to manage and maintain.

1 is a view showing a conventional method for driving a plurality of generators in parallel and various devices required therein.

2 is a view showing the configuration of a parallel operation generator control apparatus according to the present invention.

Figure 3 is a block diagram showing the components and signal flow of the parallel operation generator control apparatus according to the present invention.

4 is an overall time flow diagram showing the operating principle of the generator control according to the present invention.

5 is a time flow diagram illustrating the lower stages of a generator synchronization operation.

6 is a time flow diagram illustrating a generator control operation in accordance with a load distribution mode.

7A is a time flow diagram illustrating generator control operation in accordance with a fixed frequency mode.

7B is a time flow diagram illustrating generator control operation in accordance with the main power mode.

8 is a diagram illustrating a user interface according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

101,102,103: generator 111,112,113: engine

121,122,123: governor 131,132,133: voltage regulator

141,142,143: Load regulator 151,152,153: Synchronizer

181, 182, 183: circuit breakers 211, 212, 213: detection means

201,202,203: Integrated Control Module 320: Signal Regulator

330: analog-to-digital converter 340: processing and computing means

350: storage means 360: user interface

370: governor 380: voltage regulator

390: warning light 810: display screen

820: user input unit 830: situation display unit

840: control unit

The present invention for achieving the above object is a means for detecting the magnitude, phase, frequency of the voltage / current of each generator, the phase, frequency and voltage of the reference voltage bus (211,212,213); A signal regulator (320) for removing noise from the detected generator voltage and current and a voltage waveform of a reference voltage bus; Means (330) for analog-to-digital conversion of the output of the signal conditioner; Storage means (350) for storing the digital conversion values; Processing and computing means (340) for processing and calculating the digital conversion values to generate a plurality of output signals; And user interface means 360 for inputting user setting values into the processing and computing means and displaying a plurality of output signals from the processing and computing means to the user, wherein the processing and computing means 340 comprises: By comparing the magnitude, phase, and frequency of each generator voltage / current with a predetermined reference value, a warning signal 391 is generated to indicate whether the generator corresponds to overcurrent, overvoltage, overfrequency, reverse power, or asynchronous. .

The present invention according to another embodiment, the processing and calculating means 340, the generator voltage by comparing the magnitude, phase, frequency of the voltage of each generator with the magnitude, frequency, phase of the voltage of the reference power bus, When the voltage is less than the reference power bus, an external automatic voltage regulator 380 generates a voltage increase adjustment signal for increasing the generator voltage. When the generator voltage is greater than the voltage of the reference power bus, The voltage regulator 380 generates a voltage decrease adjustment signal that causes the generator voltage to be decreased. When the frequency of the generator voltage is greater than the frequency of the reference power bus voltage, an external governor 370 reduces the engine speed. Generate a frequency decrease adjustment signal, wherein the frequency of the generator voltage is greater than the frequency of the reference power bus voltage. When the is more characterized by generating an adjustment signal to increase the frequency increases to cause the engine speed to an external speed governor (370).

According to another embodiment of the present invention, the processing and calculating means 340 may reduce the frequency by comparing the frequency of each generator voltage based on a value of 0.07 to 0.3 Hz larger than the frequency of the reference power bus voltage. And generating an adjustment signal or a frequency increase adjustment signal.

The present invention according to another embodiment, the processing and calculating means 340, 1) calculates the effective power sharing value for each generator from the magnitude, phase, frequency of each generator voltage / current, the active power The sharing value is compared with the effective power sharing set value determined for each generator according to a predetermined effective load sharing ratio, and when the effective power sharing value is larger than the effective power sharing set value, the engine speed is set by the governor 370 of the corresponding generator. Generate an active power reduction adjustment signal for reducing, and generate an active power increase adjustment signal for increasing the engine speed by the governor 370 of the corresponding generator when the active power sharing value is smaller than the active power sharing set value; ; 2) calculating a reactive power sharing value for each generator from the magnitude, phase, and frequency of each generator voltage / current, and calculating the reactive power sharing value for each generator according to a predetermined reactive load sharing ratio; In comparison, when the reactive power sharing value is larger than the reactive power sharing set value, the reactive voltage reduction adjustment signal for causing the voltage regulator 380 of the corresponding generator to increase the field voltage of the corresponding generator is generated, and the reactive power sharing value is generated. When the reactive power sharing value is smaller than the set value, the voltage regulator 380 of the corresponding generator may further generate a reactive power increase adjustment signal for reducing the field voltage of the corresponding generator.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, in adding reference numerals to the components of each drawing, the same reference numerals are used for the same components even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

2 is a view showing the configuration of a parallel operation generator control apparatus according to the present invention. 2, except for the detection means 211, 212, 213 for detecting various voltages and currents, various devices required for generator control have a structure integrated into the integrated control module 201, 202, 203. This is based on the fact that the various measurements required for various generator control devices operate with the same common measurand such as the same voltage and current.

3 is a block diagram showing the components and signal flow of the parallel operation generator control apparatus according to the present invention. Only the parallel operation control apparatus for the generator 101 will be described below. For the other generators 102 and 103, only the corresponding detection means 212 and 213, the governors 122 and 123, the automatic voltage regulators 132 and 133, etc. are different, but the operating principle is the same.

The bus voltage 221, generator voltage and current 231 detected by the detection means 211 are converted into a state suitable for sampling by removing noise from the signal regulator 320. The output of the signal conditioner 320 is sampled by the analog-to-digital converter 330 at an appropriate sampling frequency Fs and zero-order hold to be a digital value which is a value suitable for processing in the processing and computing means 340. Is converted to. The sampling frequency Fs may vary depending on the type of power generation voltage and the like, and is 50 μsec in the preferred embodiment.

The processing and calculating means 340 uses the magnitude, frequency, phase of the measured bus voltage, and the magnitude, frequency, and phase of the measured generation voltage / current to generate values necessary for controlling various generators later, and compares them with reference values. According to the comparison result, an output signal to an external device such as a governor or a voltage regulator is generated. Various values required for generator control are calculated as follows.

1) Effective value of generated voltage / current (Veff, Ieff)

Veff = √ (V1 ² + V2 ² + .... Vn ² )

Ieff = √ (I1 ² + I2 ² + .... In ² )

Where V1, V2, ... Vn are the respective voltage sampling values, and I1, I2, ... In are the respective current sampling values.

2) Frequency of generating voltage / current (Fgv, Fgi)

Fgv = 1 / (tv1-tv2)

Fgi = 1 / (ti1-ti2)

Where tv1, ti1 represents the first time the polarity of the voltage or current changes from negative to positive, and tv2, ti2 represents the second time of the polarity of the voltage or current changing from negative to positive.

3) Phase (Pv, Pi) and phase difference (Pg) of the generated voltage and current

Pv = tv1-t0

Pi = ti1-t0

Pg = tv1-ti1

Where t0 is the synchronization reference time (t = 0).

4) Power Factor of PF

PF = cos (Pv-Pi)

5) Active power (P) and reactive power (Q) of the generator

P = Veff * Ieff * cos (Pv-Pi)

Q = Veff * Ieff * sin (Pv-Pi)

The processing and calculating means 340, in conjunction with the memory device 350, compares the various values calculated as described above with predetermined reference values, determines whether there is overcurrent, overvoltage, reverse power (overcurrent measurement, overvoltage measurement, Reverse power measurement), and compares the magnitude, phase, and frequency of the bus voltage 221 to generate an output signal for synchronizing the generated voltage with the bus voltage and transmitting it to an external device such as a governor 370 or a voltage regulator 380. (Generator Synchronous Control), and generates an output signal for adjusting the load sharing ratio shared by each generator and transmits it to external devices such as the governor 370 and the voltage regulator 380 (load control control), various warning signs and various Generate output signals to user interface 360 and separate alert device 390 to display values to the user (instrument and instrument function).

4-7B are time flow diagrams illustrating algorithms in which various control functions occur in the processing and computing means. It will be described in detail below.

4 is an overall time flow diagram showing the operating principle of generator control according to the present invention. The signals detected by the detection means 211 (step 410) are compared with various reference values, i.e., reference current, voltage and power values, by the processing and calculating means (step 420). When an overcurrent is detected to cause an error, a warning signal is generated to notify the user, that is, the generator driver (step 480). The generated warning signal drives the user interface 360 or a separate warning device 390 to inform the user of an abnormality and detects and confirms whether the abnormality is normal until the normal operation. Repeat 420 and step 480. This performs the traditional measurement of current and voltage.

If it is determined in step 420 that the generated voltage or the like is normal, the parallel operation execution command of the corresponding generator is input by the user through the user interface 360 to start parallel operation control (430). First, the processing and calculating means 340 receives a signal indicating whether the circuit breaker 181 of the generator is closed or open (step 440), and if the generator is open, the generator synchronization operation required for parallel operation is not performed. Perform step 481. If it is closed, it is determined that there is no need to perform the generator synchronization operation because it is already in parallel operation and proceed to the next step.

After the generator synchronization operation is performed, the user inputs a user input for selecting a mode indicating how to operate the generator through the user interface 360. There are three operation modes. First, the load share mode in which each generator that will be in charge of parallel operation provides the corresponding power according to a predetermined load sharing ratio, and secondly, the frequency of the generating static pressure is constant according to the predetermined rated frequency. It is a fixed frequency mode in which the share ratio is determined, and a third power source (Base Power Mode) which produces a certain amount of power irrespective of the load applied according to a predetermined predetermined generated power (reactive power and active power).

After the generator synchronization step 481, the process proceeds to any one of steps 482,483, and 484 according to the mode selected by the user. This step is continuously executed and repeated in the corresponding operation mode until another mode is selected.

5 is a time flow diagram illustrating the lower stages of a generator synchronization operation. First, a signal is received to confirm whether the generator is operating normally and whether the bus voltage is normally applied (step 510), and it is determined whether the magnitude, frequency, and phase of the generated voltage match the magnitude, frequency, and phase of the bus voltage. The control signal is generated and transmitted to an external device for matching at each step (steps 520 to 540).

First, in the generation voltage magnitude control step (step 520 and step 560), if the magnitude of the generation voltage is greater than the bus voltage, the processing and calculating means 340 is supplied to the voltage regulator (AVR) 131 of the generator 101 to generate the generation voltage. Generates a voltage increase adjustment signal for increasing the magnitude of the signal, and transmits it to the voltage regulator 131. If the magnitude of the generated voltage is smaller than the bus voltage, the processing and calculating means 340 may adjust the voltage regulator of the generator 101. (AVR) 131 generates a voltage decrease adjustment signal for reducing the magnitude of the generated voltage and transmits it to the voltage regulator 131 so that the voltage regulator 131 increases or decreases the magnitude of the generated voltage to the bus. Make sure the magnitudes of the voltages match. The generated voltage is detected again by the detection means 211, and it is judged again whether or not the coincidence with the bus voltage is fed back and the process is repeated.

If the magnitudes of the generated voltages coincide, the process proceeds to a step of matching the frequencies of the generated voltages (steps 530 to 570). Frequency matching is a frequency increase adjustment signal that causes the processing and computing means to compare the frequency of the bus voltage and the generated voltage so that if the frequency of the generated voltage is small, the governor of the engine of the corresponding generator increases the engine speed to increase the frequency of the generated voltage. Is generated and transmitted to the overspeed governor 370, and if the frequency of the generated voltage is large, the overspeed governor 370 of the engine of the corresponding generator generates a frequency decrease adjustment signal 371 to reduce the engine speed to reduce the frequency of the generated voltage. To the governor. The frequency of the generated voltage increased or decreased by the governor is re-detected by the detecting means 211 and fed back to the processing and calculating means 340 to repeat this process.

In a preferred embodiment the frequency of the generator voltage is not completely coincident with the frequency of the bus voltage, but is chosen such that the frequency of the generator voltage has a range of frequencies greater than the frequency of the bus voltage. This is to prevent damage to the bus due to sudden load when the generator is connected to the bus voltage. It is preferable that the fixed range generally has a value of 0.07 Hz to 0.3 Hz.

Finally, the phase of the generated voltage is detected by the detection means 211, which is compared with the phase of the bus voltage by the processing and computing means so that the phase increase / decrease adjustment signal when the phase of the generated voltage is faster / slower than the bus voltage. Is sent to the phase adjuster to match the phase of the generated voltage with that of the bus voltage.

When the generator voltage and the bus voltage are synchronized as described above, the generator synchronization step is terminated by closing each circuit breaker to connect the generators to the bus voltage (step 550).

6 is a time flow diagram illustrating a generator control operation according to a load distribution mode. Selection of the load distribution mode is determined by user input via the user interface 360.

Steps 610 and 620 represent matching the magnitude and frequency of the generated voltage back to the bus voltage. When the generator is connected to the bus voltage, a certain amount of load is applied, so the size and frequency of the generator are momentarily reduced by external factors such as the resistance of the line to the load. In steps 610 and 620, the voltage and frequency are increased again through the engine governor 370 and the voltage regulator 380 of the corresponding generator as a step for compensating the voltage and frequency drop.

Steps 630, 670 and 640, 680 represent adjusting the output active / reactive power of the generated voltage, respectively. In the load sharing mode, the output power for each generator is determined according to a predetermined load sharing ratio, which is defined as an active power sharing setpoint and a reactive power sharing setpoint of each generator. In general, the load sharing ratio for parallel operation of generators in an optimal state is that each generator performs load sharing at an equal rate. For example, if the first 500 kw generator and the second 200 kw generator are operated in parallel at a load sharing ratio of 50%, the effective power sharing set value of the first generator is 250 kw and the effective power share set value of the second generator is 100 kw. If two generators of the same capacity run in parallel at a 50% sharing rate, the effective / reactive power sharing setpoint shared by each generator will be half of the active / reactive power of the bus voltage.

The processing and calculating means 340 compares the effective / reactive power sharing set value with the actual effective / reactive power sharing value calculated from the generated voltage and current, and then adjusts each adjustment signal to the governor 370 or the voltage regulator 380. By adjusting the engine speed or generator field voltage, each effective / reactive power sharing value is adjusted.

If the active power sharing value is less than the active power sharing set value calculated according to the predetermined share ratio, then the overspeed governor generates an active power increase / decrease signal that increases or decreases the engine speed of each generator and increases the engine speed. When decreasing, the generated current increases / decreases, thereby increasing / decreasing the effective power sharing value. The increased / decreased real power sharing value is fed back by the detection means 211, compared with the real power sharing set value again, and then it is determined whether the ?? wave increase / decrease signal is generated and this process is repeated.

The adjustment of the reactive power sharing value is achieved by adjusting the voltage of each generator. If the reactive power sharing value is larger / less than the reactive power sharing set value calculated according to the predetermined sharing ratio, the processing and calculating means 340 generates a reactive power reduction / increase adjustment signal, and receives the reactive power reduction / increase signal. The voltage regulator of each generator increases / decreases the field voltage of each generator, thereby increasing / decreasing the power factor of the generator, thereby reducing / increasing reactive power. The reduced / increased reactive power sharing value is fed back by the detection means 211 to be compared with the reactive power sharing set value again and this adjustment process is repeated again.

The user may operate the generator in various other modes without operating the generator in the load distribution mode. This depends on the use of the generator depending on the embodiment in which the parallel operation of the generator is required. Representative cases include a fixed frequency mode and a base power mode.

7A is a time flow diagram illustrating a generator control operation according to a fixed frequency mode. The fixed frequency mode is a method in which the load sharing ratio is determined according to the load applied because power is generated at a predetermined predetermined frequency regardless of the bus voltage. Regardless of the power provided by the bus voltage, the load shared by the generator is determined according to the load, so the generator is used as a main power source. Since the frequency of the generated voltage is matched to a predetermined value, the control operation in this mode is made through the governor control through engine speed regulation (steps 710 and 740).

7B is a time flow diagram illustrating the generator control operation according to the main power mode. Main power mode is a way of driving the generator to supply a certain amount of power regardless of the bus voltage or load sharing policy. Similar to the algorithm of the load distribution mode in that the generator supplies predetermined active and reactive power, the predetermined active / reactive power value is not determined by the load distribution ratio between the generators, but by the user. It is distinguished from the load distribution mode in that it is a specific value required according to the implementation situation. The processing and calculating means 340 provides a signal for controlling the governor to adjust the effective power value in steps 720 and 750, and processes the signal for controlling the voltage regulator for adjusting the reactive power value in steps 730 and 760. Calculation means 340 provides.

According to a preferred embodiment, in comparing the measured values with reference values in three modes for measuring operation for overcurrent / overvoltage warning, generator synchronization operation, and parallel operation (420, 520, 530, 540, 610, 620, 630, 640, 710, 720, 730), the compared reference values are in a range of dead zones. ) May be included. Dead zones mean that the values being compared can have a certain acceptable range, to prevent the system from always being unstable due to excessive voltage regulation. The dead zone is determined according to the environment in which the system of the present invention is used, such as the type of engine, and is generally preferably ± 5% to ± 10% of the comparison reference value (for example, the effective power sharing setpoint).

8 illustrates a user interface 360 according to an embodiment of the present invention. The user interface includes a display screen 810 for displaying various measured voltages, currents, power levels, phases, frequencies, etc. to a user, and a user input unit 820 for inputting various predetermined values such as load sharing ratios. The controller 840 includes a status display unit 830 in which various warning lamps exist for informing a user of an operation state of the system and a warning of overcurrent measurement.

As described above, according to the parallel operation generator control apparatus according to the present invention, by controlling a plurality of various devices required for parallel operation with a single microprocessor, the cost can be reduced, the failure rate is low, management management and maintenance Easy maintenance of generator parallel operation control is possible.

Claims (4)

As a protective control device of a parallel running generator, Means (211,212,213) for detecting the magnitude, phase, and frequency of the voltage / current of each generator and the magnitude, phase, and frequency of the voltage of the reference voltage bus; A signal regulator (320) for removing noise from the detected generator voltage and current and a voltage waveform of a reference voltage bus; Means (330) for analog-to-digital conversion of the output of the signal conditioner; A warning signal 391 indicating whether the current corresponds to an overcurrent, an overvoltage, an overfrequency, a reverse power, or an asynchronous is compared by comparing the magnitude, phase, and frequency of each generator converted into the digital value with a predetermined reference value. Generating processing and calculating means 340; Storage means (350) for storing the digital conversion values; And And user interface means (360) for inputting user setting values into said processing and computing means and displaying a plurality of output signals from said processing and computing means to a user. The method of claim 1, wherein the processing and calculating means 340, By comparing the magnitude, phase and frequency of the voltage of each generator with the magnitude, frequency and phase of the voltage of the reference power bus, When the generator voltage is less than the voltage of the reference power bus, an external automatic voltage regulator 380 generates a voltage increase adjustment signal for increasing the generator voltage, and when the generator voltage is greater than the voltage of the reference power bus. An external automatic voltage regulator 380 generates a voltage decrease adjustment signal that causes the generator voltage to be reduced; When the frequency of the generator voltage is greater than the frequency of the reference power bus voltage, an external governor 370 generates a frequency decrease adjustment signal for reducing the engine speed, and the frequency of the generator voltage is greater than the frequency of the reference power bus voltage. When small, the external governor 370 generates a frequency increase adjustment signal to increase the engine speed, It characterized in that the parallel driving generator protection control device. The method of claim 2, wherein the processing and calculating means 340, And comparing the frequency of each generator voltage with a value greater than 0.07 to 0.3 Hz greater than the frequency of the reference power bus voltage to generate the frequency decrease adjustment signal or the frequency increase adjustment signal. Device. The method of claim 2, wherein the processing and calculating means 340, Calculate an effective power sharing value for each generator from the magnitude, phase, and frequency of each generator voltage / current, and compare the active power sharing value with an effective power sharing set value determined for each generator according to a predetermined effective load sharing ratio. , When the active power sharing value is greater than the active power sharing set value, the governor 370 of the generator generates an active power reduction adjustment signal for reducing the engine speed, and the active power sharing setting is greater than the active power sharing set value. When the value is small, the governor 370 of the corresponding generator generates an effective power increase adjustment signal for increasing the engine speed; The reactive power sharing value for each generator is calculated from the magnitude, phase, and frequency of each generator voltage / current, and the reactive power sharing value is compared with the reactive power sharing set value determined for each generator according to a predetermined reactive load sharing ratio. , When the reactive power sharing value is greater than the reactive power sharing set value, a reactive power reduction adjustment signal for causing the voltage regulator 380 of the corresponding generator to increase the field voltage of the corresponding generator is generated, and is greater than the reactive power sharing set value. When the reactive power sharing value is small, the voltage regulator 380 of the generator generates a reactive power increase adjustment signal for reducing the field voltage of the generator. It characterized in that the parallel driving generator protection control device.