RU207387U1 - Intelligent device of guaranteed power supply based on renewable energy sources - Google Patents

Abstract

The utility model relates to conversion equipment and can be used for efficient power take-off from solar panels, conversion and transmission of the received energy to the industrial network and consumer load. The technical result achieved when using the proposed device is to increase the energy received from the solar panel unit with partial shading due to the determination of all zones of local maxima on the I – V characteristic of the panel unit and power take-off at the point of the true maximum. The technical result is achieved due to the fact that an intelligent device of guaranteed power supply based on renewable energy sources consists of a solar panel unit, a DC / DC voltage converter, a DC bus, a reversible inverter, an LC filter, an RFI filter, a controlled network switch, a DC control unit. / DC voltage converter, reversible inverter control unit, microprocessor control and commutation unit. The smart, renewable energy-assured power supply also contains current and voltage sensor blocks on the solar panel, on the DC bus, at the output of the converter, on the load and on the grid. The DC / DC voltage converter control unit is designed with the function of tracking all local maxima on the I - V characteristic of the panel unit. In addition, the smart device may additionally contain a storage battery, a supercapacitor unit and an additional renewable energy source (RES), as well as DC / DC voltage converters for charging / discharging a storage battery, a supercapacitor unit and a renewable energy source (RES). The smart device also contains a battery control unit, a supercapacitor unit and additional renewable energy sources. 4 c.p. f-ly. 7 ill.

Description

The utility model relates to converter technology and can be used for efficient power take-off from solar panels, conversion and transmission of the received energy to the industrial network and consumer load. It is also possible to obtain energy from an additional source of renewable energy sources, charging with energy obtained from renewable energy sources or the network, storage batteries and supercapacitors with further conversion, if necessary, into alternating voltage of industrial frequency to provide the consumer's load with guaranteed uninterrupted power supply.

A solar-powered device containing a solar module, a first DC-DC converter, a storage battery, a second DC-DC converter, a controller and a load is known (RF patent for invention No. 2503120 "Solar-powered device", IPC H02M 3/156).

The disadvantages of this device are:

1. inability to track several local points of maximum power on the I - V characteristic of the panel block;

2. lack of communication with the industrial network in order to ensure the battery charge in bad weather conditions, the inability to supply energy to the network.

Known power plant containing solar cell batteries, energy storage, DC / DC voltage converter, DC / AC voltage converter, circuit breakers (RF patent for invention No. 2397593 "Power plant and its control method", IPC H02J 7/35, H01L 31/00 ).

The disadvantages of this device are:

1. inability to transfer energy received from solar panels to the industrial network;

2. inability to charge a storage battery from an industrial network, in the absence of energy from solar panels.

A device and method for tracking the maximum power point for inverters, for example, in photovoltaic applications " , IPC H02M 7/44).

The disadvantages of this device are:

1. Tracking the classic maximum on the I - V characteristic of the panel unit and its drift when the temperature changes and the illumination changes uniformly. Not tracking several local maxima on the I - V characteristic of the panel unit with partial shading, as a result - ineffective power take-off from the solar panel unit with partial shading;

2. inability to use this device as a backup power source in the event of a power failure.

The closest in technical essence to the claimed solution is an energy conversion system with tracking the maximum power point, consisting of a maximum power point tracking unit (MPPT), a DC bus, a power converter, a converter controller (Patent US 20130027997 A1 "Maximum power point tracking for power conversion system and method thereof ", IPC H02M 7/44).

The disadvantages of this device are:

1. Tracking the classic maximum on the I - V characteristic of the panel unit and its drift when the temperature changes and the illumination changes uniformly. Not tracking several local maxima on the I - V characteristic of the panel unit with partial shading, as a result of which there is a shortage of power from the solar panel unit with partial shading;

2. the absence of an energy storage device (battery or super capacitor), and, consequently, the inability to supply the load with this system in the event of a power outage or with low energy production by solar panels.

The technical problem of the claimed utility model is the determination of all zones of local maxima on the I – V characteristic of a block of panels, including with partial shading, and tracking the true point of maximum power under real operating conditions; transmission of the received energy to the network and load, as well as the charge of the energy storage unit from the solar panel unit, from the network or other renewable energy source. As a result, the efficiency of power take-off from the solar panel unit with partial shading is increased, and the reliability of power supply to the consumer of electricity is increased.

The technical problem is solved due to the fact that in a smart device of guaranteed power supply based on renewable energy sources, consisting of a solar panel unit, a unit of current and voltage sensors of a solar panel unit, a DC / DC voltage converter, a DC bus, a unit of current and voltage sensors DC current, reversible inverter, LC filter, block of current and voltage sensors at the output of the converter, radio interference filter, block of current and voltage sensors on the load, load, controlled network switch, block of current and voltage sensors, network, DC / DC control unit voltage converter with the function of tracking all local maxima on the I - V characteristic of the panel unit, control unit of a reversible inverter, microprocessor control and switching unit, bi-directional DC / DC voltage converter for charging / discharging a battery, a battery, bi-directional DC / DC voltage converter for charging a / discharge of a supercapacitor block, a supercapacitor block, a renewable energy source (RES), a DC / DC voltage converter of a renewable energy source to a DC bus voltage, a control unit for AB, BSK, additional RES.

The technical result achieved when using the proposed device is to increase the energy received from the solar panel unit with partial shading due to the determination of all zones of local maxima on the I – V characteristic of the panel unit and power take-off at the point of the true maximum.

Increasing the flexibility and functionality of the consumer's power system based on this converter.

A guaranteed power supply device can act as a source of microgeneration from renewable energy sources to the grid; as a power source from renewable energy sources of the consumer's load; as a guaranteed source of power supply for the consumer in case of power failure from the network.

The increase in the reliability of the guaranteed power supply of the consumer occurs, inter alia, through the use of energy storage devices, which receive energy from solar panels, a network or other renewable energy sources according to a given algorithm, and in the event of a network voltage failure, a decrease in the received energy from solar panels or other renewable energy sources, they provide uninterrupted powering the consumer, by mixing energy from the storage device with the energy received from solar panels or other renewable energy sources on a common DC bus, with further conversion into alternating voltage and powering the consumer's load.

The claimed solution is illustrated by graphic materials, where in Fig. 1 shows a block diagram of an intelligent device of guaranteed power supply.

The diagram shows: solar panel unit (1), solar panel unit current and voltage sensor unit (2), DC / DC voltage converter (3), DC bus (4), DC bus current and voltage sensor unit (5) , reversible inverter (6), LC filter (7), block of current and voltage sensors at the output of the converter (8), radio interference filter (9), block of current and voltage sensors on the load (10), load (11), controlled switch networks (12), a block of current and voltage sensors (13), a network (14), a control unit for a DC / DC voltage converter with the function of tracking all local maxima on the I - V characteristic of a panel unit (15), a control unit for a reversible inverter (16), microprocessor control and switching unit (17), bi-directional DC / DC voltage converter for charging / discharging the storage battery (18), storage battery (AB) (19), bi-directional DC / DC voltage converter for charging / discharging the supercapacitor unit (20), supercapacitor unit (BSK) (21), DC / DC voltage converter RES to DC bus voltage (22), additional renewable energy source (RES) (23), control unit AB, BSK, additional RES (24).

The device works as follows.

The voltage and current from the solar panel unit (1) through the unit of current and voltage sensors from the solar panels (2) is fed to the DC / DC voltage converter (3). Information about voltage and current from solar panels is sent to the DC / DC control unit by a voltage converter with the function of tracking all local maxima on the I - V characteristic of the panel unit (15), in accordance with the specified algorithm, the unit generates control signals for the operation of the DC / DC converter, in As a result, the maximum possible power is taken from the solar panels at a given temperature, illumination and partial shading of the panels. The resulting electricity is fed to the DC bus (4). From the DC bus through the block of current and voltage sensors of the DC bus voltage and current are supplied to a reversible inverter (6), which in the direct conversion mode converts DC voltage and current into AC voltage and current, for example, using pulse width modulation. Further, the power PWM signal is fed to the input of the LC filter (7), after which the filtered low frequency signal of the network is fed to the input of the current and voltage sensors at the output of the converter (8). Then the signal goes to the input of the radio interference filter (9). Further, the output current and voltages are fed to the load (11) through the unit of current and voltage sensors on the load (10), as well as to the network (14) through the controlled network switch (12) and the unit of current and voltage sensors (13). The reversible inverter is controlled by the reversible inverter control unit (16), which receives information about the current and voltage on the DC bus, as well as at the output of the converter. The complete operation of the device is controlled by a microprocessor control and switching unit (17), which receives information from the DC / DC voltage converter control unit (15), the inverter control unit (16), from the units of current and voltage sensors at the converter output, on the load and networks.

It is also possible that the system contains a storage battery (19) and a bi-directional DC / DC voltage converter unit for charging / discharging the storage battery (18).

It is also possible that the system contains a supercapacitor unit (SCC) (21) and a bidirectional DC / DC voltage converter for charging / discharging the supercapacitor unit (20).

It is also possible that the system contains at least one additional renewable energy source (RES) (23) and a DC / DC voltage converter of RES to the DC bus voltage (22).

When administered to the AB, BSC or additional RES system, the guaranteed power supply system contains a control unit for AB, BSC and additional RES (24).

Let's consider the options for the device operation in various configurations.

1. Without AB, BSC and additional renewable energy sources.

Energy from solar panels is taken at the point of maximum power and converted into alternating voltage. Next, the microcontroller analyzes the current and voltage across the load and network. If the energy received from the solar panels is sufficient to power the load, the converter disconnects the network from the load and the power is supplied only from the solar panels. If the load consumes less than the solar panel unit (BSP) generates, then the converter directs part of the energy received from the BSP to the load, and part to the network. If the energy consumed by the load exceeds the energy generated by the BSP, then the converter gives all the energy received from the BSP to the load, and consumes the remaining energy for the load from the network. In the absence of a load, all the energy received from the BSP goes to the grid.

2. With AB and (or) BSK.

In the presence of AB and (or) BSC in the system, the general operation algorithm described above does not change, however, additional options for the system operation appear. In the presence of energy from the BSP and its partial consumption for the load, the rest of the energy goes to charging the AB and (or) the BSC. After they are fully charged, the energy goes to the network. In the event of a mains voltage failure, the control and commutation microcontroller disconnects the network from the system and the load, and the consumer's load is supplied from the BSP. With a lack of energy received from the BSP, the stored energy from the AB and (or) the BSC is supplied to the DC bus, which is then converted into an AC voltage of industrial frequency to power the consumer's load. If the energy received from the BSP is not enough to load and maintain the charge of the AB and (or) the BSC in a charged state in a certain time interval, then according to a given algorithm (for example, at night) the inverter works in the reverse mode - charging the DC bus from the industrial network, and then the voltage converters charge AB and BSC to a given level.

3. Introduction of an additional source of renewable energy sources into the device.

An additional source of RES through a converter of its voltage to the voltage of the DC bus is connected to the DC bus and ensures its operation in the two possible variants described above (with and without energy storage devices). Depending on the type of additional RES, the control unit for AB, BSC and additional RES manages energy from the additional RES, as well as from AB and BSC. This unit is also connected to a microcontroller control and commutation unit for programming and controlling the system as a whole. Depending on the type of additional RES, you can programmatically set the priority for powering the load and charging the AB and BSC from the network or additional RES, including taking into account the night tariffication of electricity from the network.

Consider the operation of a solar panel unit under various operating conditions. FIG. 2 shows a family of volt-ampere characteristics of a solar panel depending on temperature and changes in the uniform illumination of the panel. The current-voltage characteristic (CVC) has a classic form: at the initial stage, there is a linear increase in power with an increase in voltage, then an extremum is reached, after which there is a decrease in the received power with an increase in the voltage on the solar panel. We see that in this case, there is only one extremum on the I – V characteristic of the panel, which, with a change in temperature and a uniform change in radiation, drifts along the I – V characteristic in a limited region.

As the temperature rises, the voltage at the point of maximum power drops. The extremum of the power function on the I – V characteristic is shifted down and to the left. With a decrease in temperature: the voltage rises at the extremum point, the maximum power point shifts up and to the right along the I - V characteristic. With a decrease in the uniform illumination of the panel, the current at the point of maximum power decreases, and the power extremum shifts downward. With an increase in the uniform illumination of the panel, the current increases, therefore, the point of maximum power shifts up.

Various algorithms for tracking the maximum power point are known. For example, disturbances and observations or the method of increasing conductivity. The essence of the perturbation and observation method is shown in Fig. 3. The voltage and current are measured on the solar panel unit (BSP). The power P0 is calculated. Next, the output voltage of the BSP is changed by controlling the converter (positive voltage increment). Current and voltage are measured. The result is a power point P1. P1 and P0 are compared, if P1 is greater, then the voltage increment remains and then the next step takes place. The voltage on the panel assembly increases. The current is measured. The power P2 is calculated. Further also P3 and P4. If the new power is lower than the previous one, then the sign of the increment changes. There are also adaptive algorithms in which the increment step is not constant, but changes, depending on the approach to the extremum. The step decreases in the region of the extremum to reduce the ripple of the power taken from the solar panel unit.

As a result, we have, with a smooth change in temperature and a uniform change in the panel illumination, the classical algorithm for finding the maximum power point tracks how the extremum drifts along the I - V characteristic of the solar panel in a given area, in principle, without examining what is happening in the entire range of operation of the solar panel unit. Once, having found the maximum, he tracks it.

Research and practice of using solar panel blocks connected in parallel, in series or in parallel in series have shown the appearance in the I - V characteristic of a block of panels of several local maxima with partial shading of a part of the panels from the entire block.

For example, consider daisy chaining six solar panels. The maximum power point voltage of each panel under normal conditions and a standard illumination level of 33 V, the current is 8 A. FIG. 4 we see the I - V characteristic of a block of six solar panels connected in series with uniform illumination. In the figure, we see one extreme at 198 V, power 1500 W. When shading three of the six panels, a situation arises when the operating current of the shaded panels is not more than 1 A, and the operating current of the unshaded panels is 8 A. if shaded and non-shaded panels are connected in series, the I – V characteristic of the panel block will have two extrema (Fig. 5).

FIG. 5 we see that the extremum corresponding to the voltage of 198 V actually went down and is at the level of 200 W. At the same time, to the left of it, a new maximum appeared on the I - V characteristic at the voltage level of 100 V and power of 750 W. The physical sense of the first extremum at 198 V is that the shaded area current flows through all six panels, resulting in a total power of 200 W. The physical meaning of the second extremum at the level of 100 V is that when a current flows equal to the current of the unshaded panels, the shaded panels are shunted by the locking diodes of the panels, as a result, the voltage of the panel block is reduced to the voltage of the sum of the unshaded panels, while the power is 750 W.

The classical algorithm for finding the maximum power point, having tuned to one maximum under uniform illumination (point A, Fig. 6), will drift downward with it (point B, Fig. 6) with partial shading of the panels. And it will not track the emergence of a new maximum (point C, Fig. 6). Accordingly, the device will work ineffectively, and take away power several times less than is possible from the solar panel unit.

To solve this problem, the claimed device provides a DC / DC voltage converter control unit with the function of tracking all local maxima on the I – V characteristic of the panel unit, which provides power take-off from the true maximum at a given time. One of the possible implementations of this function is as follows. The DC / DC voltage converter control unit divides the input voltage range into N voltage samples (see Fig. 7). The range starts at the level of the minimum voltage of one panel, and ends at the level of the maximum total voltage of the panels included in the block. Further, for each point, the current is measured and the power is calculated (P ₁ , P ₂ ... P _N-1 , P _N ). As a result of this operation, the microcontroller "recognizes" the zones of all local maxima. And then, having selected the maximum value at a given moment in time, it applies an adaptive algorithm for searching and tracking the maximum power point, for example, the method of disturbance and observation. Then, after a certain set time, the control unit turns off the disturbance and observation algorithm. It passes through all N samples of the input voltage, measures N powers. And he decides whether a new maximum has appeared on the I - V characteristic of the panel block, exceeding the one at which the converter worked in the last time interval. If not, the control unit activates the disturbance and observation method at the old maximum power point. If a new interval with a maximum is found, then the search for the maximum power according to the classical algorithm is carried out in a new range.

This algorithm of work allows you to monitor both temperature changes, a decrease in the uniform illumination of the panels, and partial shading of the panels with the appearance of local maxima. By quickly adjusting to the true point of maximum power, the declared algorithm allows you to increase the amount of energy received from the array of solar panels under real operating conditions. This is of paramount importance both for autonomous power supply systems without a network, and for systems with a network, because ultimately affects the amount of energy received from solar panels and the payback of the system as a whole.

Claims (5)

1. Intelligent device of guaranteed power supply based on renewable energy sources, consisting of a solar panel unit, a unit of current and voltage sensors of a solar panel unit, a DC / DC voltage converter, a DC bus, an inverter, a unit of current and voltage sensors at the output of the converter, a control unit DC / DC voltage converter with tracking of the maximum power point on the I-V characteristic of the panel unit, inverter control unit, control and commutation microcontroller, characterized in that it additionally includes a DC bus current and voltage sensor unit, an LC filter, a radio interference filter, a sensor unit current and voltage across the load, while the inverter is made reversible, and the control unit for the DC / DC voltage converter is made with the function of tracking all local maxima on the I - V characteristic of the panel unit. 2. Intelligent device of guaranteed power supply based on renewable energy sources according to claim 1, characterized in that it includes a bi-directional DC / DC voltage converter for charging / discharging a storage battery, a storage battery (AB). 3. Intelligent device of guaranteed power supply based on renewable energy sources according to claim 1, characterized in that it includes a bi-directional DC / DC voltage converter for charging / discharging a supercapacitor unit, a supercapacitor unit (BSC). 4. Intelligent device of guaranteed power supply based on renewable energy sources according to claim 1, characterized in that an additional renewable energy source (RES), DC / DC voltage converter of renewable energy sources to the DC bus voltage are introduced into it. 5. Intelligent device of guaranteed power supply based on renewable energy sources according to claim 1, characterized in that it includes a control unit for AB, BSC and additional RES.

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