KR100294274B1 - Apparatus for controlling power factor - Google Patents

Abstract

PURPOSE: An apparatus for adjusting power factor for single phase power is provided to reduce power loss and increase utilization ratio of electric facility by automatically improving power factor to correspond to the varying inductive load. CONSTITUTION: An apparatus comprises a current transformer(40) and a potential transformer(50) for detecting current and voltage of a power line(20), respectively; an A/D converter(60) for converting the detected current and voltage into digital signals; a non-volatile storage unit(70) for storing parameters for power factor operation and adjustment, accumulated power and reactive power; a micro processor(90) for calculating the difference between the current power factor and target power factor, by using the current and voltage signals and parameters output from the A/D converter, outputting a switching signal for selecting the capacity of the capacitor corresponding to the calculated difference, and integrating the power and reactive power; a capacitor array unit(100) where the capacitor selected by the switching signal of the micro processor is connected to an inductive load(30) of the power line so as to adjust power factor of the power line; and a communication unit(120) for remotely controlling parameter setting and monitoring power line state.

Description

Power factor regulator for single phase power {APPARATUS FOR CONTROLLING POWER FACTOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power factor adjustment apparatus for single phase power, in particular, by adjusting the power factor of a power line to which an inductive load using single phase power is applied, thereby eliminating the overload phenomenon of the pole transformer due to the power factor drop of the power line and The present invention relates to a power factor adjustment apparatus for single-phase power, in which a communication function is added to enable power factor control while remotely monitoring a state of.

In general, when the apparent power in the AC circuit is Pa, the active power is P, the reactive power is Pr, the voltage is V, and the current is I, the relationship between power and power factor is as follows.

In other words, in an AC circuit, reactive power is a power in which reactive energy, that is, energy that does not do anything when an AC voltage is applied to a load including an inductive component, continuously circulates between the power supply and the load. The magnitude represents reactive power (Pr), and in the case of single-phase alternating current, the voltage is calculated as V and Pr = VIsinθ when the current is 1, and the active power (Active Power, P), which is the power actually consumed by the load, is P Calculated as = VIcosθ. In addition, the apparent power (Apparent power) is a value (Pa) generally used to represent the load of the AC load or the power supply, and in the case of single-phase alternating current, calculated as Pa = VI, cosθ, which is a ratio of the above-described effective power and apparent power. It is called power factor, and the power factor is usually expressed as a percentage and it can be seen that 100% is ideal.

On the other hand, when the load is an inductive load in the AC circuit, when the AC power passes the inductive load, a ground current is generated, that is, the current phase is earlier than the voltage phase, so that the aforementioned power factor is lowered.

This increases the reactive power that constantly circulates between the AC power and the load without doing anything, increasing the power loss due to the high load of the power line or the pole transformer, and adding more equipment costs such as increasing the capacity of the transformer. do.

Therefore, in order to improve the power factor of the power line of the AC power source to 98% or more as possible, the power factor is improved by generating a phase current by connecting a capacitor, that is, a capacitor having a capacitive component, to the inductive load in parallel. Reduced power loss and reduced equipment costs.

Since the conventional power factor adjusting device is dedicated to three-phase electric power, which has a relatively high electric power demand, the conventional power factor adjustment is performed to prevent the overload phenomenon of the pole transformer due to the power factor drop of the single-phase power line due to the increase in demand for home appliances. The device has a problem in that it is difficult to apply power factor adjustment in single phase power.

In addition, the conventional power factor adjustment device has a communication function, there is a problem that the maintenance is inconvenient because the remote control and remote monitoring is impossible.

Therefore, power factor correction for power lines subjected to a large amount of inductive loads, such as street lamps and security lamps using household single-phase power lines and coiled ballasts, in which inductive loads are gradually increasing, is needed. In this case, power factor correction is required immediately in case of heavy load fluctuations such as when the power consumption is changed at any time and when the street lamp and security lamp are lit in a symmetrical manner. A power factor automatic adjustment device with power integration function and communication function is needed to collect accumulated power and accumulated reactive power and monitor power line conditions.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to detect a power factor of a power line to which an inductive load using single phase power is applied, and to combine a predetermined number of capacitors provided with the power factor of the power line. By adjusting and improving the power factor, it eliminates the overload phenomenon of the pole transformer due to the power factor drop of the power line, and also adds the power integration function and communication function to enable power factor control while remotely monitoring the accumulated power and accumulated reactive power. It is to provide a power factor adjustment device for single phase power.

An apparatus for adjusting power factor for single phase power according to the present invention is a device for adjusting the power factor of a single phase power line having a fluid load, and includes a current transformer for converting and outputting the current of the single phase power line at a predetermined current ratio, and a voltage of the power line at a predetermined voltage ratio. A transformer for transforming and outputting, an A / D converter for converting and outputting the measured signals from the transformer and the transformer, respectively, and outputting them as digital signals, and a predetermined parameter for power saving and power factor calculation and adjustment. The difference between the current power factor and the target power factor is calculated based on the nonvolatile storage unit that stores the accumulated power and reactive power, and the detected current and voltage signals from the A / D converter and the parameters from the nonvolatile storage unit. Microcomputer outputs a switching signal to select the capacitive capacitor array corresponding to the difference and integrates power and reactive power Comprising a processor and a given number of capacitor banks and features are switched on the basis of the switching signal of the microprocessor to a selected capacitor to yirueojim including parts connected in parallel to the inductive load of the power line array capacitor for adjusting the power factor of the power line

On the other hand, the parameters stored in the non-volatile storage unit is characterized in that it comprises a current ratio, the transformer ratio, the number of capacitor banks, the capacitor individual capacity.

In addition, a predetermined key for resetting and storing the parameter and confirming the current state of the power line, accumulated power and reactive power, and a key input unit for outputting a key signal corresponding to a user's key operation to a microprocessor, and a display control signal. And a display unit for displaying the current state of the power line and integrated power and reactive power according to the present invention, and the microprocessor updates and stores the parameter corresponding to the key signal for parameter reset in the nonvolatile storage and the key for checking the state of the power line. And a display control signal indicating the state of the current power line, the accumulated power, and the reactive power based on the signal.

In addition, the communication unit is connected to the communication port of the micro-processor to receive the parameter reset request from the remote site and the status check request signal from the power source, and to transmit the status of the power line from the communication port of the microprocessor, and the accumulated power and reactive power signals to the remote site. It characterized in that it further comprises.

The apparatus may further include a monitoring unit configured to monitor a monitoring signal applied from the microprocessor at a predetermined period using an internal delay timer, and output a reset signal for initializing and automatically restoring the microprocessor if the monitoring signal is not applied within the predetermined period. do

1 is a block diagram of an apparatus for adjusting power factor for single phase power according to the present invention.

FIG. 2 is a detailed block diagram of the capacitor arrangement of FIG. 1. FIG.

* Explanation of symbols for main parts of the drawings

10: single phase AC power source 20: power line

30: inductive load 40: current transformer

50: transformer 60: A / D conversion unit

70: nonvolatile storage 80: key input

90: microprocessor 100: capacitor arrangement

110: display unit 120: communication unit

130: monitoring unit

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the invention described below with reference to the accompanying drawings by those skilled in the art.

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

1 is a block diagram of an apparatus for adjusting power factor for single phase power according to the present invention, wherein a single phase AC power source 10, a power line 20, an inductive load 30, a current transformer 40, a transformer 50, A / D conversion unit 60, nonvolatile storage unit 70, key input unit 80, microprocessor 90, capacitor arrangement unit 100, display unit 110, communication unit 120 and monitoring unit 130 ).

In the figure, the single-phase AC power supply 10 supplies a predetermined single-phase AC power supply through the power line 20, and the inductive load 30 is a load having a reactance, that is, an inductive component. It is a street light and a security light or an electric motor having a, it can be configured by selectively connecting a plurality of loads in parallel to the power line (20).

In addition, the current transformer 40 is commonly referred to as a CT (Current Transformer), and includes a primary coil and a secondary coil having a predetermined winding ratio (the reciprocal of the current ratio) to connect the power line 20 to the primary coil, and to induce the secondary coil. Detected current is outputted.

In addition, the transformer 50 is commonly referred to as a PT (Potential Transformer), and has a primary coil and a secondary coil having a predetermined winding ratio (inverse of the transformer ratio), and are provided at both ends of the inductive load 30 connected to the power line 20. Connect the primary coil to and detect and output the transformed voltage induced in the secondary coil.

Meanwhile, the A / D (Analog to Digital) converter 60 converts the current and the voltage transformed from the current transformer 40 and the voltage transformer 50 into digital signals, respectively, and outputs the digital signals. And the current flow and the voltage applied to the transformer 50 are weak analog signals, so that various noise components are removed, amplified, and converted into digital signals.

In addition, the nonvolatile storage unit 70 may include a current ratio of the current transformer 40, a voltage ratio of the transformer 50, a number of capacitor banks of the capacitor array unit 100, and a capacitor individual capacitor. EEPROM (Electrically Erasable and Programmable Read Only Memory) or VNSRAM (storage) that stores parameters including values, etc., stores accumulated power and reactive power by the microprocessor 90 described below, and stores and stores data stored without power. None Configured using Volatile Static Random Access Memory) or Flash Memory.

In addition, the key input unit 80 includes a predetermined number including a key for resetting a parameter used for power factor adjustment and a key for checking a current state such as current, voltage, power, reactive power, and inverse rule of the current power line 20. And keys, and outputs a key signal corresponding to a user's key operation.

On the other hand, the microprocessor 90 calculates the current power factor, target power factor, reactive power, and the like based on the current stored in the A / D converter 60 and the current stored in the nonvolatile storage 70. Set the capacitor capacitance value closest to the amount of power change and output a switching signal for parallel connection to the inductive load 30 through the I / O port, and integrate the power and the reactive power to the nonvolatile storage unit 70. Save it.

In addition, the microprocessor 90 supplies a predetermined key signal (for example, a key signal for selecting a setting parameter and an up / down designation key signal for parameter up / down) to reset a parameter from the key input unit 80. The reset parameter is controlled and updated in the nonvolatile storage unit 70 based on the request. When the password is requested and the input password applied to the predetermined key signal from the key input unit 10 matches the preset password, Perform parameter reset control.

In addition, the microprocessor 90 is based on a predetermined key signal for checking the state of the power line of the key input unit 80, for example, current, voltage, power factor, instantaneous reactive power, instantaneous power, integrated power. , A display control signal for displaying integrated reactive power, etc.) is applied to the display unit 110 described later.

In addition, when the microprocessor 90 is connected to the communication unit 120 to be described later connected to the internal communication port and the parameter reset request signal and the power line status check request are received from the remote place, the normal request date is performed through the ID verification process and the password verification process. In this case, the parameter reset control process and the current power line state are applied to the communication port.

In addition, the microprocessor 90 outputs a monitoring signal to a monitoring unit 130 to be described later at a predetermined period, and when a reset signal is applied from the monitoring unit 130, the microprocessor 90 initializes its own process and automatically recovers its own error process. .

Meanwhile, in the capacitor array unit 100, a capacitor bank selected based on a switching signal from the microprocessor 90 is connected to the inductive load 30 in parallel to vary the capacitive load on the power line 20 to change the power line. The power factor of 20 is adjusted, and as shown in Fig. 2, the capacitors C1 to C8 of the same capacity or utilization in the form of 6 banks, 8 banks or 12 banks are arranged in parallel in a single-phase power line in the same number of switches ( In combination with SW1 to SW8, each is connected to the I / 0 ports 0 to 7 of the microprocessor 90, and switches SW1 to SW8 based on the same number of binary switching control signals of the microprocessor 90. ) Is switched on / off to change the capacitance of the entire capacitors C1 to C8.

The display unit 110 displays the state of the current power line 20 based on a display control signal from the microprocessor 90, and is configured using an LCD (Liquid Crystal Display) or the like.

In addition, the communication unit 120 is a transmission and reception means for parameter setting control and power line status monitoring at a remote location. The communication unit 120 is connected to a communication port of the microprocessor 90 to receive a parameter reset request signal and a status check request signal from a remote location. A status signal of a power line from the communication port of 90 is transmitted to a remote location, for example, to perform digital serial communication via a RS-232C interface if it is close to a remote location, and a modem ( MODEM) to configure analog serial communication.

On the other hand, the watchdog 130 has an internal delay timer and operates a delay timer if a watch signal is not sent from the microprocessor 90 within a set time, and applies a reset signal to the microprocessor 90 when the delay timer is operated. do.

Next, an operation process of the power factor adjusting apparatus for single phase power according to the preferred embodiment of the present invention having the above-described configuration will be described.

First, in the single phase power line 20 having the inductive load 30, the line voltage and the current flowing through the line are measured through the current transformer 40 and the transformer 50, and the signal is converted into the A / D converter 60. After conversion into a digital data signal through the microprocessor 90 is input.

Then, the microprocessor 90 calculates the voltage, current, and reactive power based on the input voltage and current value, calculates the power factor based on the data, and then converts the switching signal through the I / 0 port to the capacitor array unit 100. The capacitance value is adjusted so that the power factor is 98% or more by variably controlling the total capacitance value of the capacitors C1 to C8 selected by applying to the switches SW1 to SW8, that is, connected to the capacitive load 30 in parallel. In addition, the calculated power and the reactive power are integrated to store the integrated power and the accumulated reactive power in the nonvolatile storage unit 70.

Power factor fluctuates according to the increase and decrease of inductive loads, so it is possible to control the voltage and current continuously and calculate the feedback and control the capacity value, and check the accumulated power and reactive power. It is possible to check the power usage state.

On the other hand, in the single-phase power factor adjustment apparatus according to the preferred embodiment of the present invention having a display and manual parameter setting scheme, a predetermined key signal for confirming the current state of the power line 20 from the key input unit 80 is a microprocessor. When applied to 90, the microprocessor 90 displays a display control signal for displaying voltage, current, instantaneous power, instantaneous reactive power, integrated power, integrated reactive power, and power factor values which are the states of the current power line 20. The value calculated by applying the measurement operation 110 to the display unit 110 can be confirmed.

In addition, when a key signal for setting or resetting a parameter from the key input unit 80 is applied to the microprocessor 90, the password may be matched through a process for verifying a password in order to prevent parameter reset of a user other than the administrator. In this case, the parameters are updated and stored in the nonvolatile storage unit 70 in response to the key signal from the key input unit 80.

On the other hand, when the remote control system (not shown) for the remote communication control and monitoring system is assigned an ID and sends a communication request signal through the communication unit 120, the microprocessor 90 compares with the set ID and the current measurement operation is processed. The power line state data is uploaded to the remote control system through the communication unit 120.

In addition, when the remote control system sends a parameter setting request signal through the communication unit 120, the microprocessor 90 requests the password to the remote control system.

At this time, when the password is transmitted from the remote control system, the microprocessor 90 receives it through the communication unit 120, compares it with a preset password, and matches the parameter setting value stored in the nonvolatile storage unit 70 if it matches. Upload to the remote control system and receive the changed parameter value to update the parameter value stored in the nonvolatile storage unit (70).

In addition, the microprocessor 90 recalculates the measured value according to the changed parameter, outputs a corresponding switching signal to the capacitor array unit 100, adjusts the power factor of the power line 20, and recomputes the remote control system. Upload the data. The above situation is processed in real time, and thus the remote control system can monitor the state of the power line 20 at the moment.

On the other hand, for abnormality detection and automatic recovery of the power factor adjusting device, the process in the microprocessor 90 periodically applies a monitoring signal to the monitoring unit 130 while executing each routine.

At this time, the monitoring unit 130 operates the delay timer if the monitoring signal is not sent from the microprocessor 90 within the set time with the internal delay timer, and if the delay timer is operated, the monitoring unit 130 returns to the microprocessor 90. The reset signal is applied.

Then, the microprocessor 90 receiving the reset signal from the monitoring unit 130 is initialized to automatically recover the abnormal process of the microprocessor 90 itself.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

As described above, according to the present invention, in a single-phase power line having an inductive load, the power factor can be automatically improved in response to the variation of the inductive load, thereby reducing power loss and increasing the effective utilization rate of the electrical equipment. Collecting power and accumulated reactive power, and remote monitoring of the state of the waiting line, can be convenient for maintenance.

Claims (1)

A current transformer for converting and outputting a current of a power line at a predetermined current ratio, a transformer for converting and outputting a voltage of the power line at a predetermined voltage ratio, and converting and outputting signals measured from the current transformer and the transformer into digital signals, respectively. An A / D conversion unit, a nonvolatile storage unit for storing predetermined parameters required for power factor calculation and adjustment, integrated power and integrated reactive power, current and voltage signals detected from the A / D conversion unit, and the nonvolatile storage unit Calculates the difference between the current power factor and the target power factor based on the parameter from the negative and outputs a switching signal for selecting the capacitive capacitor array corresponding to the difference. If the numbers match, control the updating of parameters and add power and reactive power to save the non-volatile storage. A capacitor array having a microprocessor, a predetermined number of capacitor banks, and switched based on a switching signal of the microprocessor, the selected capacitor being connected in parallel to the inductive load of the power line to adjust the power factor of the power line; A communication unit connected to a communication port of the microprocessor to receive a parameter reset request signal from a remote site and a status check request signal of a power line, and to transmit a power line status signal including accumulated power and integrated reactive power from the communication port to a remote site; A supervisor that monitors a supervisory signal applied from the microprocessor at a predetermined period with an internal delay timer, and outputs a reset signal for initializing and automatically restoring the microprocessor if a supervisory signal is not applied within a predetermined period, and resets a parameter. And a key input unit having keys for checking the current state of the power line including integrated power and integrated reactive power, and a display unit for displaying a current state of the power line under the control of the microprocessor. Power factor adjuster.