KR100439647B1 - Portable Anglemeter - Google Patents

Abstract

The present invention relates to a manufacturing technology of a portable angle meter for measuring a phase-difference angle of a power system device, wherein the phase difference is an important index for efficiency, power factor, power system stabilization and protection relay system correction. For example, it is measured for installation, inspection and correction of protective relays in power generation and substations.

Conventional technologies / products include PMM1 Power Multi-Meter (AVO International, UK) and portable current transformer tester (Inventor Han Hong-seok et al. 3), and are used as portable measuring instruments in Korea Electric Power Corporation. Since the portable current transformer tester is suitable for the current transformer characteristic test, it is necessary to develop a technology necessary for the production of a portable angle meter that is easy to use, low cost, and easy to maintain, only for the phase difference angle measurement of power system equipment.

The present invention, which is developed by the above-mentioned necessity, is a portable meter dedicated to measure the phase difference angle of a power system facility based on a microprocessor in real time, a portable multimeter function capable of measuring voltage and current, auto-ranging function, and measurement It is a portable angle meter that can realize results recording and display function, communication function that enables searching, printing and setting from an external device, localization of the use environment, and simple operation by menu operation.

The present invention provides an operation switch panel equipped with a terminal block and an operation switch for electrical connection with an external device, a power operation circuit for opening and closing a power supply, a power supply device for converting and supplying a power to an appropriate level, and a system. CPU, which is a central processing unit equipped with measurement and signal processing algorithm, digital signal input circuit for reading the operation switch status, voltage current detection circuit for detecting voltage current signal and converting it to the appropriate level, and digital signal Analog signal input circuit to convert to, gain control circuit for automatically optimizing the measurement range of voltage and current, display device driving circuit, key controller, communication controller, semiconductor memory device, consisting of clock and LED and clamp type Software for analyzing test data on personal computers and accessories such as current transformers Characterized in that comprising: a program, and the like; It is characterized by eliminating the effects of noise and uncertainty by the zero-crossing method by applying the Phaser Measurement technique, which realizes an algorithm for calculating the electric quantity by two parameters of magnitude and phase angle. It is a portable angle meter characterized by the addition of a gain control circuit for realizing auto-ranging in which the measurement range is automatically adjusted according to the voltage-current signal detection level.

Description

Portable Anglemeter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable angle meter dedicated for measuring phase difference angles of power devices such as generators and transformers, which are power system elements, and measures for testing electrical characteristics of power equipment. And the technical field of manufacturing test apparatus.

The phase difference angle of power equipment is a difference angle between phases of two voltages / currents and is an indicator of efficiency, power factor, and power system stabilization, and is an important parameter especially for correction of power system protection relay system. The phase difference test of the target power equipment is carried out when new construction, repair, inspection and correction of protective relay are performed. In addition to KEPCO and large-capacity power consumers, the measurement of phase difference is carried out by heavy electric manufacturers, power equipment builders, and research institutes. For this reason, research and development is being avoided by instrument manufacturers.

A summary of the conventional techniques / products related to the phase or phase difference measurement is shown in Table 1 of the phase difference technique / product summary table.

TABLE 1

Phase difference measurement technology / product summary table

As shown in Table 1, DPM609 Digital Phase-meter (Feedback Instruments Ltd., UK), SD1000 Phase Meter (CNN, Malaysia), GP102 Multi-function Gain-phase Analyzer (Clark-hess, USA), 6000 Phase Meter (Clark -hess, USA), PMM1 Power Multi-Meter (AVO International, UK) and portable current transformer tester (Patent No. 0206655, 1999.02.09, patent holder KEPCO, inventor Han Hong-seok et al.) The related technologies / products are classified as follows:

-Laboratory Practice: DPM609 Digital Phase-meter and 6000 Phase Meter

-Calibration: SD1000 Phase Meter

-Low pressure system, for system characteristics test: GP102 Multi-function Gain-phase Analyzer

-For portable and versatile measurement of high voltage system equipment: PMM1 Power Multi-Meter and Portable Current Transformer Tester

PMM1 Power MultiMeter and Portable Current Transformer Tester are used as on-site portable measuring instruments of power systems by domestic agencies and companies such as Korea Electric Power Corporation. In terms of economic and maintenance, the portable current transformer tester is suitable for the characteristics test of the current transformer, and it is problematic to effectively apply the phase difference angle test of various types of power equipment.

As described above, when reviewing conventional technologies / products, development of portable angle meters that are simple to use, low-cost, and easy to maintain, such as electric resistance and voltage / current measuring circuits (Multi-Testers) that are commonly used. This is required.

It is a task of the present invention to develop a technology for the manufacture of a portable angle meter that is easy to use, inexpensive, and easy to maintain, for measuring the phase difference angle of an ultra high voltage power system and a power facility, and the features and functions of the present invention are as follows:

ㆍ Feature

-Portable measuring instrument for measuring phase difference angle of high voltage power system

-Real time measurement based on microprocessor

-Auto-ranging function

-Portable multimeter function

-Record, display, communicate (download, print) and set measurement conditions of measurement results

-Realizes the voltage, current, phase and phase difference measurement technique by phaser operation based on the Discrete Fourier Transform (DFT) technique, which eliminates the influence of noise and the uncertainty of phase measurement by zero-crossing method.

ㆍ Setting

-Setting items: Measurement target device information (business name / device name / device number), environmental information (date and time)

-Setting method: Menu type setting by 4 keys

ㆍ Operation

-Operation items: ON / OFF, measurement mode switching, display mode switching

-How to operate: ON / OFF switch, measurement switch and display switch

Display

-Display items: Switching display items among phase difference angle, three phase phase, three phase voltage and three phase current

Display: LCD

ㆍ Measure

-Measurement item: Switching of measurement items among phase difference angle, three phase voltage / current / phase

Phase difference angle: ± 0 ~ 180˚, resolution 0.05˚, accuracy 0.5˚

Phase: ± 0 to 180˚, resolution 0.05˚, accuracy 0.5˚

Voltage: 0 ~ 650Vac (Auto Ranging), Resolution 0.02% of FS, Accuracy 0.5% of FS

Current: 0-100 Aac (Auto Ranging), Resolution 0.02% of FS, Accuracy 0.5% of FS

ㆍ Record

-Recording medium: S-RAM kbyte

-Recording capacity: 300 measurement data

ㆍ Communication and printing

Communication port: RS232

-Communication speed: 38,400kbyte

-PC monitoring software program: data upload / download, search and print

ㆍ Other

-Korean language of use environment

-Simple operation: Minimize setting items, menu type operation by 4 keys

1 is a block diagram of a portable angle meter according to the present invention.

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

01: Terminal Block 02: Power Control Circuit

03: operation switch panel 04: power supply device

05: Central processing unit (CPU) 06: Bus (Bus)

07: Digital signal input circuit 08: Voltage current detection circuit

09: analog signal input circuit 10: display device driving circuit

11: Key Controller 12: Communication Controller

13: memory device (RAM / SRAM) 14: gain control circuit (Gain Controller)

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

1 is a block diagram of a portable angle meter according to the present invention.

1, 01 is a terminal block, 02 is a power control circuit, 03 is a control switch panel, 04 is a power supply, 05 is a central processing unit (CPU), 06 is a bus (Bus), 07 is a digital signal input (DI) Circuit, 08 is a voltage and current detection circuit, 09 is an analog signal input circuit, 10 is a display device driving circuit, 11 is a key controller, 12 is a communication controller, 13 is a memory device (RAM / SRAM), 14 Denotes a gain control circuit, respectively.

In Figure 1, the terminal block 01 is a terminal for electrical connection between the portable angle meter and the external device of the present invention from the left to the power supply terminals (P, N, E), voltage signal terminals (V ₁ , V ₂ , V ₃₎ , G), current signal terminals (A ₁ , A ₂ , A ₃ ) are arranged,

P-terminals of the power terminals P, N, and E are positive poles of the power source, N-terminals are negative poles of the power source, and E-terminals are connected to the ground poles to receive power;

The terminal voltage signal _{(V 1, V 2, V} 3, G) of _{V 1, V 2, V 3} , G- voltage terminal are each test element of the subject device (normally, the three-phase power device, a, b, c phase Voltage and neutral) to input an analog voltage signal;

A ₁ of the current signal terminal _{(A 1, A 2, A} 3), A 2, A 3 - terminal detects a current component (typically three-phase power device, a, b, c phase current) of each test subject device Connected to a clamp type current transformer to input an analog current signal.

In FIG. 1, the power supply operation circuit 02 includes an electronic switch, an overcurrent protection circuit, and a power display lamp, and the power supply terminals P, N, and E according to the operation of the 'power switch' of the operation switch panel 03. The power flowing from the power supply flows safely and is opened and closed to supply power to the power supply device 04.

In FIG. 1, the operation switch panel 03 is a switch panel including a power switch, a measurement mode switching switch, and a display mode switching switch.

By switching the power switch 'power' to 'ON' or 'OFF' to turn the electronic switch of the power supply control circuit 02 on or off to interrupt the power supply of the angle meter of the present invention;

The measurement mode switch is an automatic reset push button for switching two measurement modes (phase difference measurement mode and three-phase voltage / current / phase measurement mode), and the measurement mode is alternated each time the button is pressed. The contact state of the push button is input to the digital signal input circuit 07 to be switched;

The display mode switching switch is an auto-return type push button for switching four display modes (phase difference angle, three phase phase, three phase voltage and three phase current display mode) of the display device, and the display mode alternates each time the button is pressed. The contact state of the push button is input to the digital signal input circuit 07 so as to be switched.

In FIG. 1, the power supply device 04 is a device for supplying required DC power of the portable angle meter of the present invention, and is connected to an internal power supply including a CPU 05 and a power supply of a peripheral device.

In Fig. 1, the CPU 05 is a microprocessor, and includes a system OS program, various measurement algorithms, various input / output interface (I / O interface) programs, and man-machine interface (MMI) programs of the portable angle meter of the present invention. And receive data / commands from various interfaces and peripheral devices connected to the busbar 06, and manage the system according to a user's instruction through the MMI. The present invention relates to a phase difference measurement algorithm based on a phaser operation based on the Discrete Fourier Transform (DFT) described above. PFT) DFT calculation module for calculating magnitude and frequency component using Discrete Fourier Transform (DFT), and each output frequency of the DFT calculation module. And a phase angle calculating module for calculating a phase angle of each signal from a number component, and a phase difference calculating module for calculating a phase difference between phases of each signal calculated by the phase angle calculating module. There are two ways to use phasor and zero-crossing. Comparing the advantages and disadvantages of the above two methods, the pager method is simply calculated by software, but there is a possibility of error when the instantaneous waveform of the waveform is excessive, and the zero-crossing method guarantees the error in ppm under the assumption that the noise is not serious. Therefore, it has higher reliability than the pager method. However, in order to use the zero-crossing method, there is a disadvantage that the noise of the measured signal value is not serious and a separate hardware device is required. Since additional measuring devices are implemented by applying the zero-crossing method, additional additional hardware is required. A device was required. In order to solve this problem, in the present invention, the central processing unit (CPU) attempts to measure the phase difference by using the pager method. The problem of noise in applying the phasor method was solved by performing noise filtering in the voltage and current detection circuit 08. In order to measure the phase difference by the phasor method, from the instantaneous value of the fundamental wave of each three-phase signal, Each of the phaser real part Vre and the imaginary part Vim must be obtained, and the real part and the imaginary part of each phaser of the three-phase signal are each obtained by a Discrete Fourier Transformation (DFT) algorithm. As a mathematical formula using a discrete time function, it can be easily known to those skilled in the art, so only the basic formula (Equation 1) is introduced here, and a detailed description thereof will be omitted. Where V is the fundamental pi of the instantaneous value, N is the number of samples during one period, and n is the harmonic order. The phase in the central processing unit is obtained by using the real part and the imaginary part obtained through the discrete Fourier transform (DFT). Each calculation module can obtain each phase (θ1, θ2, θ3) of the three-phase signal using Equation 2 described below.

When the phase angle calculation module obtains the phases of the three-phase signals using the above equation, the phase difference calculation module may calculate the phase difference between the phases θ1, θ2, θ3. The circuit 07 receives a voltage signal of 0 to 5V level, which is a contact state output signal of the measurement mode switching switch and the display mode switching switch of the operation switch panel 03, and digitizes it through a logic circuit on the bus line 06. Put it up.

In FIG. 1, the voltage current detecting circuit 08 includes a signal isolation circuit, a filtering circuit, and an amplifying circuit to which an auto-ranging circuit is added, and the voltage signal terminals V ₁ , V ₂ , V ₃ , of the terminal block 01. G) and the voltages inputted from the current signal terminals A ₁ , A ₂ , and A ₃ are reduced with a resistor divider, and then the signals of 0 to 5V level are processed through signal isolation, filtering, and amplification. Output to 09). The amplification circuit to which the auto-ranging circuit is added comprises an amplifier, an amplifier gain adjustment resistor array, and a decoder to decode the code value of the gain control circuit 14 to adjust the amplification degree to auto-ranging. To realize.

In FIG. 1, the analog signal input circuit 09 receives a voltage signal of 0-5V level, which is an output signal of the voltage current detection circuit 08, and digitizes it by means of an analog to digital convertor (ADC) on the bus line 06. Put it up.

In Fig. 1, the gain control circuit 14 outputs an amplification degree setting signal of the voltage current detection circuit 08 to realize auto-ranging of the input signal level. The gain control circuit 14 outputs digital data which is an amplification setting value of the CPU 05. It is a logic circuit which converts into a logic value and inputs it to the decoder of the voltage-current detection circuit 08.

In Fig. 1, the display device driving circuit 10, the key controller 11, the communication controller 12, and the memory element 13 are the same as computer peripherals generally used as peripheral devices of the portable angle meter of the present invention;

The display device driving circuit 10 is a driver of the liquid crystal display for displaying the measured data and the set value in the text mode. The display operation and input of the measured data or the set data is handled by a menu (Manu).

The key controller 11 is a driver for controlling four keypads (menu key, enter key, cursor up / down key or setting data increase / decrease key) for inputting setting data,

The communication controller 12 is a communication driver for receiving measurement data or setting data of the personal computer and the portable angle meter of the present invention,

The memory device 13 is a semiconductor reservoir capable of power failure compensation for storing measurement data and setting data,

Other peripheral devices include a timer and LEDs for indicating the system status of the portable angle meter of the present invention.

According to the development of the manufacturing technology / product of the portable angle meter according to the present invention, it becomes possible to use the measuring instrument for measuring the differential angle in an institution / company which is involved in the manufacture, installation, operation, maintenance, repair, and inspection of ultra high voltage power system equipment. As a result of the acquisition of relevant metrology techniques, the instrumentation work body is expected to have the following technical and economic benefits:

ㆍ Technical Effect

-Improved reliability technology of instruments that can be applied under very high pressure environment up to 765kV

-Applied electric field measurement technology by pager operation based on DFT technique (reduced measurement error and reduced uncertainty in general, compared to zero-crossing technique)

-Real time measurement based on microprocessor

-Korean language of use environment

-Simple operation: Minimize setting items, menu type operation by 4 keys

Economic effect

-Domestic demand: more than 300 total demands, including KEPCO (about 370 locations including power generation and substations, power management offices, power research institutes), heavy electric manufacturers, large power consumers, power facility construction companies, and research institutes, and more than 30 annual demands (calculation)

-Sales growth: 600 million won per year (2,000 won × 30 units / year)

-Substitution of import: $ 750,000 annually ($ 250,000 per year based on MultiAmp's PMM1 price)

-Export promotion: Undecided, but international demand is expected to increase after domestic expansion.

ㆍ Other Effects

-Diversified varieties for customer service at instrument makers (prior to economic effects)

-Contribute to the development of measuring and test equipment and manufacturing technology

Claims (3)

In the power system phase difference measuring device for measuring the phase difference (Phase Difference Angle) of the power system (Power System) device, A terminal block including a power terminal, a voltage signal terminal, and a current signal terminal for electrical connection with the power system; Phaser algorithm that converts the measured signal into a phasor of fundamental harmonics, a functional unit with various interface algorithms, and a microprocessor to control the system by receiving components, data and control signals connected to the busbar A central processing unit (CPU), Signal insulation circuits for electrical isolation between external and internal signals of signals input from the voltage signal terminals and current signal terminals of the terminal block, filtering circuits for removing noise, amplification circuits for converting signals to predetermined levels, and measurement signals Voltage and current detection circuit including an auto-ranging circuit consisting of an array and a decoder for adjusting the amplifier gain to realize a level auto-ranging A portable angle meter comprising: measuring a phase difference angle by a phaser operation. The method of claim 1, wherein the central processing unit, A DFT calculation module for calculating the magnitude and frequency components of the fundamental harmonics of each output voltage signal and current signal of the power system device; A phase angle calculation module for obtaining a phase of each signal from each output frequency component of the DFT calculation module; Phase difference calculation module for obtaining the phase difference angle between the phase of each signal calculated by the phase angle calculation module A portable angle meter comprising: measuring a phase difference angle by a phaser operation. The method of claim 1, wherein the auto-ranging circuit in the voltage current detection circuit, In order to realize Auto-Ragnging in which the measuring range is automatically adjusted according to the voltage and current signal detection level, an additional gain control circuit which converts an amplification setting value into a logic signal and outputs it from a decoder in the voltage and current detection circuit is additionally added. Portable angle meter, characterized in that it comprises a.