KR100917307B1 - Stand-alone power supply system for water pump motor using solar cells - Google Patents

Abstract

A power supply system is provided to supply the power to a pump without an additional energy source by converting the solar energy into the electric energy. A solar cell(101) converts the sunlight into the DC power. The solar cell is connected to the front part of a power converter. A pump(103) is connected to the rear of the power converter. A power converter(102) includes solar irradiance determining unit, a condenser, and an inverter. The solar irradiance determining unit determines whether the solar irradiance exceeds the minimum operation range of the pump. If the solar irradiance does not exceed the minimum operation range of the pump, the condenser stores the DC power from the solar cell. If the solar irradiance exceeds the minimum operation range of the pump, the inverter inverts the DC power form the solar cell to the AC power for the pump.

Description

STAND-ALONE POWER SUPPLY SYSTEM FOR WATER PUMP MOTOR USING SOLAR CELLS

The present invention relates to a stand-alone power supply system using a solar cell for pumping motor pump, more specifically, the operating state of the system and the supply power to the pumping motor pump according to the amount of solar radiation, the DC voltage from the solar cell and pumping The present invention relates to a stand-alone power supply system for controlling the maximum output point tracking of the solar cell by controlling the PI input to the VVVF inverter based on the AC current supplied to the motor pump.

There is a problem that the supply of agricultural water or drinking water is not smooth because non-systemic areas or mountainous areas, islands, deserts, etc., which are not powered, cannot use a pumping motor that operates by electricity.

In order to solve this problem, a method of operating a pumping motor pump using a diesel generator is commonly used. However, diesel generators have a new problem such as the high cost of fuel used to operate the generator and the need to go for fuel.

For this reason, a method of supplying power to a pump motor for pumping by using sunlight as a natural energy has been studied. The method of supplying power using solar light is generally divided into a standalone type and a grid-connected type. Independent type refers to the type of self-power generation, that is, the electricity generated by the power supply system is used in the place of production without being connected to the grid, and the grid type refers to the type that can receive or send electricity through the grid. .

In the case of supplying power by using sunlight, the solar radiation is not constant, so it is not possible to supply a constant power. One way to solve this problem is to use a solar inverter instead of a general-purpose converter when converting DC power from solar cells to AC power. The solar inverter includes a boost converter or a transformer that can boost and use the power when solar power is low. However, the solar inverter has the advantage of providing a constant power. However, the solar inverter is expensive compared to general-purpose inverters. It is a problem that increases the construction cost.

An object of the present invention is to enable power supply using natural solar energy, even in non-system areas and mountainous regions where power is not supplied. It is an object of the present invention to drive the pumping motor pump with the electric power supplied by the present invention, so that the supply of agricultural water or drinking water can be smoothly performed without an additional power source or fossil fuel, and as a result, the use of fossil fuel is reduced.

In addition, an object of the present invention is to maximize the efficiency of the energy by minimizing the energy lost by the power generated from sunlight does not reach the power to drive the pump pump motor. Since pumping motor pumps can use energy only within the pump's operable range, lost energy is generated if the energy supplied is not within the pump's operable range. It is an object of the present invention to minimize this lost energy.

In addition, an object of the present invention is to adjust the energy consumed in the pumping motor pump in accordance with the change of the input energy to use the solar energy near the maximum output point.

It is also an object of the present invention to suppress surge voltages that may occur in a pumped motor pump that is powered.

The present invention is a stand-alone power supply system using a solar cell for pumping motor pump, a solar cell converting sunlight into direct current power, the solar cell is connected to the front end and the pumping motor pump is connected to the rear end and the DC power It includes a power conversion unit for converting the AC power to supply to the pumping motor pump, a solar radiation amount determining unit for determining whether the solar radiation amount is more than the minimum operating range of the pumping motor pump, and a storage battery that can store the DC power, When the amount of solar radiation is above the minimum operating range of the pumping motor pump, the AC power is supplied to the pumping motor pump. When the amount of solar radiation is less than the minimum operating range of the pumping motor pump, the DC power is stored in the storage battery.

The present invention also provides a stand-alone power supply system using a solar cell for pumping motor pump, a solar cell for converting sunlight into direct current power, and the solar cell is connected to the front end and the pumping motor pump is connected to the rear end and the DC power A power converter converting AC power into AC power and supplying the pump to the pump motor, wherein the power converter converts the frequency input to the VVVF inverter based on the DC voltage from the solar cell and the AC current of the pump motor. PI control is performed to follow the maximum output point tracking of the solar cell and supply the AC power to the pump motor.

The present invention also provides a stand-alone power supply system using a solar cell for pumping motor pump, a solar cell converting sunlight into direct current power, the solar cell is connected to the front end and the pumping motor pump is connected to the rear end and the DC power A power conversion unit for converting the AC power into the pumping motor pump and supplying the pump to the pumping motor pump, a solar radiation metering unit for determining whether the amount of solar radiation is more than a minimum operating range of the pumping motor pump, and a storage battery capable of storing the DC power. Supplying the AC power to the pumping motor pump when the amount of solar radiation is greater than or equal to the minimum operating range of the pumping motor pump, and storing the DC power in the storage battery when the solar radiation amount is less than the minimum operating range of the pumping motor pump, The power converter is a DC voltage from the solar cell and the amount By on the basis of the AC current to the motor pump PI controls the frequency input to the VVVF inverter to the maximum power point tracking control of the solar cell and supplying the AC power to the motor pump yangsuyong.

According to the present invention, since solar energy, which is a natural energy, is converted into electric energy, it is possible to supply power only by sunlight in non-system areas and mountainous regions. By driving the pumping motor pump with the electric power supplied by the present invention, the supply of agricultural water or drinking water can be smoothly performed without an additional energy source such as electric power or fossil fuel, and as a result, the use of fossil fuel is reduced.

According to the present invention, when the amount of insolation is above the minimum operating range of the pumping motor pump, the electric power is supplied to the pumping motor pump, and when the amount of insolation is less than the minimum operating range of the pumping motor pump, power is stored in the storage battery to use the power as needed. It can maximize the use efficiency of energy.

Further, according to the present invention, the voltage and frequency supplied from the inverter to the pump motor for pumping can be controlled to be substantially variable voltage variable frequency, and at the same time, the maximum output point tracking control of sunlight can also be performed. In constructing the system according to the present invention, since the frequency and voltage supplied to the pump motor for pumping are controlled using the voltage supplied from the solar cell and the current supplied to the pump motor for pumping, it is used at the input side of most solar inverters. Since the current transformer does not need to be installed separately, and the load condition of the pumping motor pump is determined by the inverter, the capacitance value inside the inverter is also smaller than that of the general solar inverter, and when the voltage supplied to the power converter is low, it is supplied to the pumping motor. Since the voltage is reduced, a general-purpose inverter can be configured without using a solar inverter including a boost converter or a transformer, thereby implementing a pumping system at a lower cost.

 In addition, according to the present invention, the MSF is further included between the power conversion unit and the pump motor for pumping, and the MSF can suppress the surge voltage generated in the pump motor for pumping.

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

1 is a block diagram of a standalone power supply system using a solar cell for a pumping motor pump according to a first embodiment. The power supply system according to the first embodiment includes a solar cell 101, a power converter 102, and a pumping motor pump 103.

The solar cell 101 converts sunlight energy into electrical energy, and generates direct current power when sunlight is present.

The power converter 102 is connected between the solar cell 101 and the pumping motor pump 103, and converts the DC power generated by the solar cell into AC power to supply the pump motor for pumping 103. In order to convert the DC power into AC power, the power converter includes an inverter.

The power conversion unit 102 follows the maximum output point of the solar cell through the control of a variable voltage variable frequency (VVVF) inverter and a function of differently operating the power supply system according to the amount of solar radiation described below. It may include any one of the functions (see FIGS. 5 and 6) or both, and even if there is a separate device for performing each of these functions to be operated in conjunction with the power conversion unit 102 Can be.

A method of differently operating the power supply system according to the amount of solar radiation is described with reference to FIG. 2.

First, it is determined whether sunlight exists (step S1). If there is no sunlight, check the presence of sunlight again. Reconfirming the presence of sunlight may be performed at predetermined time intervals.

If there is sunlight, it is determined whether the amount of insolation is greater than or equal to the minimum operating range of the pumping motor pump (step S2). The minimum operating range of the pump motor for pumping means the minimum power (or solar radiation) required to operate the pump motor for pumping and to make the desired work effective. If the solar radiation amount is more than the minimum operating range of the pumping motor pump, power is supplied to the pumping motor pump (step S3). If the solar radiation amount is less than the minimum operating range of the pumping motor pump, power is stored in the storage battery (step S4).

Since the solar light may not exist and the solar radiation may change even after supplying power to the pump motor pump or storing power in the storage battery, steps S1 to S4 are repeatedly performed to reflect this.

3 schematically illustrates how the operation mode of the system changes by operating the power supply system according to the amount of solar radiation.

In the power supply system according to the present invention, if the amount of solar radiation is greater than the minimum operating range 301 of the pumping motor pump, the power generated by the solar cell is supplied to the pumping motor pump to operate the pumping motor pump 302, and the amount of solar radiation If it is less than the minimum operating range of this pump motor pump, it becomes the charging modes 303 and 304 which store the electric power produced | generated by the solar cell in a storage battery.

An example of a standalone power supply system using solar heat that performs a function of differently operating the power supply system according to the amount of solar radiation is shown in FIG. 4.

The system for the function includes a solar cell 401, the solar radiation determination unit 402, an inverter 403, a storage battery 404, and a pumping motor pump 405.

The solar cell 401 performs the same function as the solar cell 101, and the pumping motor pump 405 performs the same function as the pumping motor pump 103.

The inverter 403 performs a function of converting DC power into AC power, and is generally included in the power converter 102.

The solar radiation amount determining unit 402 determines whether the solar radiation amount is greater than or equal to the minimum operating range of the pumping motor pump. When the solar radiation amount is greater than or equal to the minimum operating range of the pumping motor pump, the inverter converts the DC power from the solar cell 401 into AC power to supply power to the pumping motor pump 405. On the other hand, when the amount of solar radiation is less than the minimum operating range of the pumping motor pump, the direct current power from the solar cell 401 is stored in the storage battery 404. The power stored in the storage battery 404 can be used according to the needs of the user.

The minimum operating range of the pumping motor pump, which is a reference for determining the operation mode of the power supply system in the solar radiation determination unit 402, may be set by a user. That is, the user can install the pump motor for pumping in the power supply system and select the optimal time for solar radiation to test the pump pump for operation of the pump to determine and set the minimum operating range of pump pump. In general, the minimum operating range for pumping motor pumps depends on the depth of the head.

In order to perform a function of differently operating the power supply system according to the amount of solar radiation, any one or both of the solar radiation determination unit 402 and the storage battery 404 may be included in the power conversion unit 102, the solar radiation determination unit ( Even when the 402 and the storage battery 404 are separately present, the function may be performed in connection with the power conversion unit 102.

Since the solar cell varies in characteristics depending on the surrounding environment such as insolation, temperature and the like, the maximum output point of the solar cell is followed in order to maximize the output of the solar cell. An example of a control device that performs the function of controlling the maximum output point tracking of the solar cell through the control of the VVVF inverter is shown in a block diagram in FIG.

The system for the function is a solar cell 501, PI controller 502, frequency converter 503, VVVF inverter 504, input voltage detector 505, output current detector 506, and pumping motor pump ( 507).

The solar cell 501 performs the same function as the solar cell 101, and the pumping motor pump 507 performs the same function as the pumping motor pump 103.

The input voltage detector 505 detects a DC voltage generated by the solar cell.

The output current detector 506 detects an AC current supplied to the pump motor for pumping.

The PI controller 502 is operated to control the maximum output point following by inputting the DC voltage generated by the solar cell and the AC current supplied to the pump motor for pumping, and outputs an appropriate signal, and the frequency converter 503 Outputs a set frequency to be input to the VVVF inverter 504 using the output from the PI control unit 502 as an input.

The VVVF inverter 504 is an inverter whose output voltage and output frequency are variable and inputs the set frequency from the frequency converter 503 to convert the DC power generated by the solar cell into AC power of the set frequency. It functions and is generally included in the power converter 102. At this time, the set frequency range is the minimum frequency capable of driving the pumping motor pump as the minimum frequency and the rated frequency of the pumping motor pump as the maximum frequency, the minimum frequency and the maximum frequency is set by the user. When the DC voltage is detected from the solar cell 501, the pumping motor pump is started from the minimum frequency to control the maximum power point tracking of the solar cell 501 within the range not exceeding the maximum frequency.

In order to perform a function of controlling the maximum output point tracking of the solar cell, any one or part of the PI controller 502, the frequency converter 503, the input voltage detector 505, and the output current detector 506. Or all may be included in the power converter 102, even if the PI controller 502, the frequency converter 503, the input voltage detector 505, and the output current detector 506 are each separate. The function may be performed in association with 102.

A method of controlling the maximum output point tracking of the solar cell through the control of the VVVF inverter will be described with reference to FIG. 6.

First, it is determined whether sunlight exists (step S1). If there is no sunlight, check the presence of sunlight again. Reconfirming the presence of sunlight may be performed at predetermined time intervals.

If there is sunlight, PI control is performed to follow the maximum power point of the solar cell by inputting the DC power generated by the solar cell and the AC power supplied to the pump motor for pumping (step S2). Thereafter, a frequency to be input as a control signal to the VVVF inverter 504 is set based on the signal output by the PI control (step S3), and the VVVF inverter 504 converts DC power based on the set frequency into AC power. (Step S4). Thereafter, the inverted AC power is supplied to the pumping motor pump (step S5), and steps S1 to S5 are repeatedly performed to continuously control the maximum power point tracking of the solar cell.

7 is a block diagram of a standalone power supply system using a solar cell for a pumping motor pump according to a second embodiment. The power supply system according to the second embodiment includes a solar cell 701, a lead terminal unit 702, a power conversion unit 703, an MSF 704, and a pumping motor pump 705.

The solar cell 701, the solar cell 101, the power converter 703, the power converter 102, and the pumping motor pump 705 perform the same functions as the pumping motor pump 103.

The incoming terminal unit 702 is connected between the solar cell 701 and the power converter 703 to prevent reverse currents that may occur in the power converter 703 and to convert the DC power generated from the solar cell 701 into power conversion. The transfer to the unit 703 is generally included in a solar cell power supply system.

The MSF 704 is connected between the power converter 703 and the pump motor 705 to suppress the surge voltage that may occur in the pump motor 705 and to convert the AC converted by the power converter 703. Transfer power to pumping motor pump.

For example, when the length of the output point of the power converter and the motor pump is separated by the head depth (more than 30m), the PWM (Pulse Width Modulation) voltage due to the inverting influences the influence of the reactance component and capacitance component of the wiring cable. Surge voltage may be generated at the input stage of the motor pump. In this case, the motor pump carries a risk of burnout such as insulation breakdown, and it can be prevented by using MSF.

In the present embodiment, the solar cell 701, the power converter 703, and the pumping motor pump 705 may be configured to further include only the MSF 704.

8 is a block diagram of a standalone power supply system using a solar cell for a pump motor for pumping according to a third embodiment. The power supply system according to the third embodiment includes a solar cell 801, an incoming terminal unit 802, a power conversion unit 803, an MSF 804, a switching unit 805, a motor pump 806, and a heater 807. ).

The solar cell 801 is the solar cell 701, the inlet terminal unit 802 is the inlet terminal unit 702, the power conversion unit 803 is the power conversion unit 703, the MSF 804 is the MSF (704) Performs the same function as

The switching unit 805 functions to select which load to supply power when two or more loads are to be connected to the power supply system. The load selected by the switching unit 805 is operated. In FIG. 8, the motor pump 806 and the heater 807 are illustrated as an example of a load, and any electric device requiring power supply may be a load.

9 is a schematic diagram illustrating an example of a pumping supply device using a standalone power supply system using a solar cell. The pumping device includes a solar cell 901, a power converter 902, a motor pump 903, and a water tank 904.

The solar cell 901 is installed at a predetermined inclination angle from the ground in consideration of the altitude of the sun. The motor pump 903 is a device for pumping water, and the water tank 904 is a device for storing water pumped by the motor pump.

The power converter 902 may include one or both of a function of differently operating the power supply system according to the above-described solar radiation, and a function of controlling the maximum output point tracking of the solar cell through the control of the VVVF inverter. have. Since the load from the pumping device is a motor pump 903, when implementing a function of differently operating the power supply system according to the amount of insolation, the minimum operating range of the load must be set based on the motor pump, and the control of the VVVF inverter is controlled. Even when implementing the function to control the maximum output point tracking of the solar cell through the minimum frequency and the maximum frequency should be set based on the motor pump.

It will be understood from the foregoing description that the foregoing and equivalents thereof may be embodied in various forms. Therefore, while the description has been described in connection with specific embodiments, the true scope of the invention should be limited by the following claims and any equivalents that may be contemplated per se to those skilled in the art, as described herein. It should not be limited by the specific embodiment.

1 is a block diagram of a standalone power supply system using a solar cell for a pumping motor pump according to a first embodiment.

2 is a flowchart illustrating a method of differently operating a power supply system according to the amount of solar radiation.

3 is a graph schematically showing how the operation mode of the system changes by operating the power supply system differently according to the amount of solar radiation.

4 is an exemplary block diagram of a stand-alone power supply system using a solar cell that performs the function of operating the power supply system differently according to the amount of solar radiation.

5 is an exemplary block diagram of a control device that performs a function of controlling the maximum output point tracking of a solar cell through control of a VVVF inverter.

6 is a flowchart illustrating a method of performing maximum output point tracking control of a solar cell through VVVF inverter control.

7 is a block diagram of a standalone power supply system using a solar cell for a pumping motor pump according to a second embodiment.

8 is a block diagram of a standalone power supply system using a solar cell for a pumping motor pump according to a third embodiment.

9 is a schematic diagram illustrating an example of a pumping supply device using a standalone power supply system using a solar cell.

Claims (8)

A solar cell converting sunlight into direct current power, The solar cell is connected to the front end and the pumping motor pump is connected to the rear end, and includes a power conversion unit for converting the DC power into AC power to supply to the pumping motor pump, independent power supply using a solar cell for pumping motor pump. In the system, The power converter, An insolation determination unit that determines whether or not the insolation amount is greater than or equal to the minimum operating range of the pump motor; A storage battery for storing DC power from the solar cell when the solar radiation amount is determined by the solar radiation determination unit to be less than a minimum operating range of the pump motor; And when the solar radiation amount is determined to be greater than or equal to the minimum operating range of the pumping motor pump, by the solar radiation determination unit, converting DC power from the solar cell into AC power for the pumping motor pump and supplying the pump to the pumping motor pump. Independent power supply system, characterized in that. delete The method of claim 1, The power converter is a stand-alone power supply system characterized in that for supplying the AC power to the pump motor for pumping by controlling the maximum output point of the solar cell. The method of claim 3, The power conversion unit controls the maximum output point tracking of the solar cell by controlling the PI input frequency to the VVVF inverter based on the DC voltage from the solar cell and the AC current supplied to the pump motor. Independent power supply system, characterized in that for supplying to the pump motor for pumping. delete The method according to any one of claims 1, 3, and 4, Independent power supply system, characterized in that it further comprises an MSF to suppress the surge voltage that may occur in the pump motor pump. As an operation method of a stand-alone power supply system using a solar cell for a pump motor for pumping with a storage battery, Setting a specific solar radiation value as a minimum operating range of the pumping motor pump connected to the power supply system; Determining whether the solar radiation value actually obtained from the solar cell is greater than or equal to a minimum operating range of the pumping motor pump connected to the power supply system; Supplying power to the pumping motor pump by converting DC power from the solar cell into AC power when the amount of solar radiation is greater than or equal to a minimum operating range of the pumping motor pump; And And storing the direct current power input from the solar cell in the storage battery when the solar radiation amount is less than the minimum operating range of the pumping motor pump. delete

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