Power conversion device

Abstract

A power conversion device according to an embodiment of the present invention comprises: a power conversion unit for converting and outputting power input from a PV module; a sensing unit for sensing the voltage and current of an input terminal of the power conversion unit; and a control unit for controlling the power conversion unit so that the power according to the voltage and current of the input terminal of the power conversion unit sensed by the sensing unit tracks a first power.

Description

power conversion device

[0001] The present invention relates to a power conversion device.

[0002] Solar power generation is becoming widely adopted as an eco-friendly energy source, replacing conventional chemical and nuclear power generation. Solar power generation can be either standalone, with a battery connected to a converter, or grid-connected. Standalone systems typically consist of photovoltaic panels, storage batteries, and power conversion equipment, while grid-connected systems are connected to commercial power sources, enabling the exchange of power with load grid lines.

[0003] Photovoltaic modules have different maximum power points depending on factors such as irradiance and temperature. To operate solar cells at their maximum power point, an optimizer or module-level power electronics (MLPE) can be used to perform maximum power point tracking (MPPT) control on a module-by-module basis.

[0004] When performing maximum power point tracking control, if more power is generated than is transmitted to the power grid, there is a problem of unstable DC-link voltage due to surplus power.

[0005] The technical problem to be solved by the present invention is to provide a power conversion device capable of stably controlling the power of a solar power generation module.

[0006] In order to solve the above technical problem, a power conversion device according to one embodiment of the present invention includes a power conversion unit that converts and outputs power input from a PV module; a sensing unit that senses voltage and current of an input terminal of the power conversion unit; and a control unit that controls the power conversion unit so that power according to the voltage and current of the input terminal of the power conversion unit sensed by the sensing unit follows first power.

[0007] Additionally, the control unit can control the voltage of the PV module to be higher than the voltage of the maximum power point of the PV module.

[0008] Additionally, the voltage of the PV module can be controlled to be lower than the voltage of the maximum power point of the PV module.

[0009] Additionally, the first power may be the target output power of the power conversion unit.

[0010] In addition, the power conversion unit supplies output to the grid, and the first power may be power that can be supplied to the grid.

[0011] In addition, the power conversion unit supplies output to a load, and the first power may be the required power of the load.

[0012] Additionally, the first power may be power according to power information received from an upper controller.

[0013] In addition, the power conversion unit may include a first power conversion unit that converts power input from the PV module into first DC power; a second power conversion unit that converts the first DC power into first AC power; and a DC link connected between the first power conversion unit and the second power conversion unit.

[0014] In addition, the control unit can control the first power conversion unit so that the output power of the PV module follows the first power, and control the second power conversion unit so that the second power conversion unit outputs the first power.

[0015] In addition, the first power conversion unit includes a plurality of first power conversion units connected in parallel, and each of the plurality of first power conversion units can be connected to a PV module.

[0016] Additionally, the power conversion unit can be connected to a plurality of PV modules.

[0017] Additionally, the power conversion unit can convert power input from the PV module into second AC power.

[0018] According to embodiments of the present invention, since the PV module can be precisely controlled to output the target power within the output range, it is easy to manage the power and energy of the entire system. In addition, since it can control to the target power in a short time even in situations where the weather changes rapidly or the PV output amount changes, the stress on the passive components in the system can be reduced, thereby increasing the lifespan. In addition, since the output power can be controlled according to each situation when there are multiple input channels, high power generation efficiency can be achieved even when the input voltage range of each channel is varied. Even if only one channel has a lower maximum voltage than the other channels, it can be controlled accordingly, and since the power of each channel can be controlled individually, it is easy to manage heat generation of the entire system. Furthermore, when using a DC / DC converter and a DC / AC inverter in conjunction, PV module power can be controlled while reducing the DC-link voltage compared to other technologies, thereby increasing the efficiency of the entire system.

[0019] Figure 1 is a block diagram of a power conversion device according to one embodiment of the present invention.

[0020] Figures 2 to 6 are block diagrams of a power conversion device according to an embodiment of the present invention.

[0021] Figure 7 is a block diagram of a power conversion device according to a comparative example of the present invention.

[0022] Figure 8 is a diagram for explaining maximum power point tracking control.

[0023] FIG. 9 is a drawing for explaining a control method of a power conversion device according to an embodiment of the present invention.

[0024] Figures 10 to 15 illustrate various embodiments of a power conversion device according to an embodiment of the present invention.

[0025] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0026] However, the technical idea of ​​the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and within the scope of the technical idea of ​​the present invention, one or more of the components between the embodiments can be selectively combined or substituted for use.

[0027] In addition, terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, may be interpreted in consideration of the contextual meaning of the relevant technology.

[0028] Additionally, the terms used in the embodiments of the present invention are intended to describe the embodiments and are not intended to limit the present invention.

[0029] In this specification, the singular may also include the plural unless specifically stated otherwise in the phrase, and when it is described as “A and / or at least one (or more) of B, C”, it may include one or more of all combinations that can be combined with A, B, C.

[0030] Additionally, in describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the components from other components, and are not intended to limit the nature, order, or sequence of the components.

[0031] And, when a component is described as being 'connected', 'coupled', or 'connected' to another component, it may include not only cases where the component is 'connected', 'coupled', or 'connected' directly to the other component, but also cases where the component is 'connected', 'coupled', or 'connected' by another component between the component and the other component.

[0032] Additionally, when described as being formed or arranged "above" or "below" each component, "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Furthermore, when expressed as "above" or "below," the meaning may include not only the upward direction but also the downward direction based on one component.

[0033] Figure 1 is a block diagram of a power conversion device according to one embodiment of the present invention.

[0034] FIGS. 2 to 6 are block diagrams of a power conversion device according to an embodiment of the present invention, FIG. 7 is a block diagram of a power conversion device according to a comparative example of the present invention, FIG. 8 is a diagram for explaining maximum power point tracking control, FIG. 9 is a diagram for explaining a control method of a power conversion device according to an embodiment of the present invention, and FIGS. 10 to 15 illustrate various embodiments of a power conversion device according to an embodiment of the present invention.

[0035] A power conversion device (100) according to an embodiment of the present invention is composed of a sensing unit (110), a power conversion unit (120), and a control unit (130), and may include a first power conversion unit (121), a second power conversion unit (122), and a DC link (140).

[0036] A power conversion device (100) according to an embodiment of the present invention may be a power conversion device that converts power of a PV module (210). It may be connected to a grid (220) or a load (240) to convert power of the PV module (210) and transmit it to the grid (220) or the load (240). In addition, it may be connected to an energy storage device (150) to store power in the energy storage device (150). The grid (220) may be a power system, and the load (240) may include a load within a home or facility. The energy storage device (ESS) may include one or more batteries. The power conversion device (100) according to an embodiment of the present invention may configure a solar power generation system together with a PV module (210), a battery (220), and the like.

[0037] The power conversion unit (120) converts and outputs power input from the PV module (210).

[0038] A PV module (210) generates electricity through solar power generation using sunlight. The PV module (210) may include a PV panel. The PV panel may include a plurality of cell strings. A solar cell that performs solar power generation may be expressed as a cell string unit in which a plurality of cells are connected in series. A cell string may include at least one cell, and when including a plurality of cells, the plurality of cells may be connected in series. A cell string may be a solar cell string including solar cells. A solar cell string may form a PV panel. A PV panel may also be referred to as a solar panel or solar power generation panel. Solar cells generate solar power (PV, Photovoltaic) by using the photovoltaic effect. The photovoltaic effect is the emission of electrons when light above a certain frequency strikes a specific metal material. A pn ​​junction is formed using a p-type semiconductor and an n-type semiconductor, and current is generated using electrons generated by the photovoltaic effect, thereby generating power. Solar cells are formed using silicon or the like, and may be formed in a wafer shape. Solar cells are located in areas with good sunlight exposure, such as fields, building exteriors, or rooftops, and generate electricity using sunlight. These solar cells can be integrated into the building, forming a building-integrated photovoltaic (BIPV) system.

[0039] Since the amount of power generated from a single solar cell is insufficient to be utilized by a load or power system, power suitable for utilization can be generated by connecting multiple solar cells in series to form a solar cell string instead of a single solar cell. A solar cell string can be a basic unit for generating power. A photovoltaic panel can be formed by forming multiple cell strings, which are basic units, into a panel. Solar cells have different voltage-current characteristics depending on the amount of sunlight, temperature, etc., and the maximum power point (MPP) also changes. (Generated power = Voltage X Current)

[0040] The power conversion unit (120) can receive first power generated and output from the PV module (210) and convert it into second power. The power conversion unit (120) can convert the first voltage of the input power into a second voltage or convert the first current of the input power into a second current. When connected to a grid (220) or a load (240), the power conversion unit (120) can convert and output power suitable for the grid (220) or the load (240).

[0041] The power conversion unit (120) may include a first power conversion unit (121) and a second power conversion unit (122). The first power conversion unit (121) may convert power input from the PV module (210) into first DC power. Since the power input from the PV module (210) is DC power, the first power conversion unit (121) may include a DC-DC converter.

[0042] The second power conversion unit (122) can convert the first DC power, which is the output of the first power conversion unit (121), into first AC power. A DC link (140) can be connected between the first power conversion unit (121) and the second power conversion unit (122), and the first DC power of the first power conversion unit (121) output through the DC link (140) can be received by the second power conversion unit (122) and converted into first AC power. The second power conversion unit (122) converts DC power into AC power and may include a DC-AC inverter. The second power conversion unit (122) may include a bidirectional inverter.

[0043] The sensing unit (110) senses the voltage and current of the input terminal of the power conversion unit (120). The sensing unit (110) can sense the voltage and current of the output terminal of the PV module (210). The sensing unit (110) can sense the voltage and current of the signal input from the PV module (210) to the input terminal of the power conversion unit (120). The sensing unit (110) can include a voltage sensor that senses voltage and a current sensor that senses current.

[0044] The control unit (130) controls the power conversion unit (120) so that the power according to the voltage and current of the input terminal of the power conversion unit (120) sensed by the sensing unit (110) follows the first power.

[0045] In solar power generation, depending on the characteristics of the relationship between current and voltage and the relationship between voltage and power, the maximum power has the characteristic of being the power when it is about 80% of the maximum voltage, not the maximum voltage. The relationship between voltage (V) and power (P) can be represented as in FIG. 8. The power conversion device (100) according to the comparative example of the present invention, as shown in FIG. 7, converts the power input from the PV module (21) by the DC-DC converter (11), converts it into AC power by the inverter (12) via the DC link (14), and transmits it to the grid (22). At this time, maximum power point tracking control can be performed to optimize the output power of the cell string so that the solar cells operate at the maximum power point (MPP), which is the operating point where the power is maximum under each condition, so that the power output from the PV module (21) is maximized. Since the maximum power point continues to change depending on the magnitude of the voltage and current generated from the PV panel, the point where the maximum power point can be generated must continue to be found. That is, to track maximum power rather than maximum voltage, the magnitude of voltage and current can be varied to achieve maximum power. In other words, voltage can be reduced and current increased in the direction of increasing power, or voltage can be increased and current reduced. This is called maximum power point tracking (MPPT), and MPPT can be used to improve the efficiency of solar power generation.

[0046] The DC-DC converter (11) performs maximum power tracking control, and the inverter (12) can control the AC output power output to the grid (22). At this time, it is difficult for the DC-DC converter (11) to simultaneously control the DC link (14) while performing MPPT control due to the characteristics of the PV module (21). Since the inverter (12) controls the AC output and the DC-DC converter (11) performs MPPT control, the DC link (14) voltage is not controlled and may vary according to the power flow. A surplus power equal to the difference between the power output by the DC-DC converter (11) to the DC link (140) and the power output by the inverter (12) to the grid (22) is applied to the DC link (140), and thus, the voltage fluctuation may increase.

[0047] When ESS is included, it is not easy to accurately control the DC link (14) voltage because charging and discharging are performed according to the DC link (14) voltage. Since there is no control over the DC link (140) voltage, voltage fluctuations increase, which may adversely affect the lifespan of the DC-link capacitor and also lower the efficiency of the inverter (12).

[0048] As environmentally friendly policies continue, the supply of renewable energy continues to increase. However, because the power grid is a physical flow of electricity, supply and demand must always be balanced to maintain stability. Therefore, if the increased renewable energy supply exceeds actual demand, it can actually harm grid stability. Consequently, power grid operation and standards now mandate that, if surplus power generated by renewable energy cannot be stored in batteries, power generation be reduced.

[0049] For example, if the PV module (21) generates 10 kW (A) and transmits it to the DC link (14) through the DC-DC converter (11), but the output of the inverter (12) is limited to 8 kW (B) depending on the grid (22) situation, the surplus power of 2 kW charges the DC-link capacitor. If the voltage of the DC link (14) increases, the response is not fast in the case of MPPT control, so the duty does not change quickly, and the power that the DC-DC converter (11) transmits to the DC link (14) decreases, and if the power transmitted by the DC-DC converter (11) decreases, the power output from the PV module (21) also becomes surplus power, which can increase the voltage of the PV module (21). If the voltage of the PV module (21) increases, the power production of the PV module (21) itself decreases due to the VP characteristic of the PV module (21), and changes to 8 kW. In this way, since the power limitation is determined by the power flow and the characteristics of the PV module (21) rather than by control, the DC link (14) voltage cannot be predicted and has instability due to instantaneous power fluctuations.

[0050] For stable power control, the control unit (130) of the power conversion device (100) according to the embodiment of the present invention controls the power conversion unit (120) so that the output of the PV module (210) follows the first power.

[0051] Here, the first power may be the target output power of the power conversion unit (120). A grid (220) or a load (240) may be connected to the output terminal of the power conversion unit (120). The control unit (130) may control the power conversion unit (120) to follow the target output power to be transmitted to the grid (220) or the load (240).

[0052] The power conversion unit (120) can supply power to the grid (220), and at this time, the first power may be power available for supply to the grid (220). As shown in Fig. 2, the grid (220) may be connected to the output side of the power conversion unit (120). The first power may be power available for supply to the grid (220), and the power available for supply may vary depending on the current power status of the grid (220). When the demand power of a device or system connected to the grid (220) is higher than the supply power, the power available for supply increases, and when the demand power is lower than the supply power, the power available for supply may decrease.

[0053] The first power may be power according to power information received from the upper controller (230). The control unit (130) may receive a signal including power that the power conversion unit (120) should output from the upper controller (230) and set the first power accordingly to control the power conversion unit (120). As shown in Fig. 3, the control unit (130) may receive power information from the upper controller (230). The power information may include control command information. Here, the upper controller (230) may include an Energy Management System (EMS) or a Power Management System (PMS). The control unit (130) may receive power information from the EMS or may receive power information via the PMS. In addition, the power information may be received from the PMS.

[0054] The power conversion unit (120) can supply output to the load (240), and at this time, the first power may be the required power of the load (240). As shown in Fig. 4, the load (240) may be connected to the output side of the power conversion unit (120). The first power may be the required power of the load (240), and may vary depending on the operating state of the load (240), the type of the connected load, the rated power, etc.

[0055] The control unit (130) can control the power conversion unit (120) so that the power currently input from the PV module (210) follows the first power. As shown in FIG. 9, the control unit (130) can control the power conversion unit (120) so that the A power input from the PV module (210) follows the B power, which is the first power. For example, when the B power is lower than the A power, the control unit (130) can control to lower the power of the input terminal of the power conversion unit (120). The control unit (130) can control in a direction (D1) that the voltage of the power of the input terminal of the power conversion unit (120) becomes higher than the voltage of the maximum power point based on the voltage of the maximum power point of the PV module (210). Alternatively, the control can control in a direction (D2) that the voltage of the power of the input terminal of the power conversion unit (120) becomes lower than the voltage of the maximum power point based on the voltage of the maximum power point of the PV module (210). Based on the voltage of the maximum power point, both the direction of increasing the voltage (D1) and the direction of decreasing the voltage (D2) can lower the power to the first power, B power.

[0056] When controlling in the direction of increasing voltage (D1), the voltage change amount becomes small and the current change amount becomes large. The small voltage change amount during voltage control enables accurate and fast control. However, when the power decreases, the voltage increases, and when the PV module (210) is turned off, the voltage may suddenly increase.

[0057] When controlling in the direction of lowering the voltage (D2), the voltage change amount becomes large and the current change amount becomes small. During voltage control, the voltage change amount becomes large and the control may become slow. However, when the power is lowered, the voltage decreases, and when the PV module (210) is turned off, the voltage can decrease without a sudden increase in the voltage, enabling stable control.

[0058] The control unit (130) may perform Input Power Point Tracking (IPPT) control to track the first power when the first power is lower than the maximum power point, and may perform MPPT control to track the maximum power point when the first power is higher than the maximum power point. In addition, the control unit (130) may perform MPPT control in a normal state, and may perform IPPT control when receiving a voltage command from the upper controller (230) or when an abnormality occurs in the grid (220) or load (240).

[0059] The power conversion unit (120) may include a first power conversion unit (121) and a second power conversion unit (122). As shown in Fig. 5, a sensing unit (110) may be arranged at an input terminal of the first power conversion unit (121), and a DC link (140) may be connected between the first power conversion unit (121) and the second power conversion unit (122). The DC link (140) may include a DC link capacitor.

[0060] The control unit (130) can control at least one of the first power conversion unit (121) and the second power conversion unit (122) so that the power calculated from the voltage and current sensed by the sensing unit (110) follows the first power. The control unit (130) can include a first control unit that controls the first power conversion unit (121) and a second control unit that controls the second power conversion unit (122), and a control unit can be formed for each power conversion unit controlled to follow the first power and controlled individually. At this time, the EMS can transmit the total power information transmitted to the final grid to the PMS, and the PMS can transmit the first power that each power conversion unit should follow to the control unit of each power conversion unit. At this time, the first power that each power conversion unit should follow can be different. Alternatively, the first power can be the same, and the voltage or current for following the first power can be different. The VP characteristics of the PV modules connected to each power conversion unit may differ, and the degree of the maximum power point may vary. Therefore, each control unit can individually control each power conversion unit. For example, one power conversion unit may control the PV module to pursue the maximum power point, and another power conversion unit may control the PV module to pursue a first power lower than the maximum power point.

[0061] The first power conversion unit (121) may be a DC-DC converter, and the second power conversion unit (122) may be an inverter. The control unit (130) may control the DC-DC converter or inverter to control the power input from the PV module (210), i.e., the output power of the PV module (210), to the first power.

[0062] In addition, the control unit (130) controls the first power conversion unit (121) and the second power conversion unit (122), and can control the first power conversion unit (121) so that the output power of the PV module (210) follows the first power, and can control the second power conversion unit (122) so that the second power conversion unit (122) outputs the first power. The control unit (130) can control the voltage of the DC link (140) by controlling the second power conversion unit (122). The control unit (130) can control the power output from the second power conversion unit (122) so that the voltage of the DC link (140) is maintained constant. The control unit (130) can maintain the voltage of the DC link (140) constant by ensuring that all of the first power output from the first power conversion unit (121) is output from the second power conversion unit (122) so that surplus power does not charge the DC link capacitor. To this end, the control unit (130) can control the second power conversion unit (122) so that the second power conversion unit (122) outputs the first power.

[0063] When an energy storage device (150) is connected to the DC link (140), the control unit (130) can control the second power conversion unit (122) according to the charging or discharging of the energy storage device (150). As shown in Fig. 6, the energy storage device (150) is connected to the DC link (140) and can be charged or discharged by power converted in the first power conversion unit (121) or the second power conversion unit (122) to supply power to the second power conversion unit (122).

[0064] When the energy storage device (150) is discharged, the control unit (130) can control the second power conversion unit (122) so that the second power conversion unit (122) outputs power that is the sum of the power output by the first power conversion unit (121) and the discharge power of the energy storage device (150). In addition, when the energy storage device (150) is charged, the control unit (130) can control the second power conversion unit (122) so that the second power conversion unit (122) outputs power that is the result of subtracting the charge power of the energy storage device (150) from the power output by the first power conversion unit (121). In this way, the DC link voltage can be stably maintained by controlling the second power conversion unit (122) according to the charge or discharge power of the energy storage device (150).

[0065] Since the DC link voltage can be controlled to a constant level, the fluctuation of the DC link voltage can be reduced, and the DC link voltage can be controlled to a target voltage, thereby improving the efficiency of the system, improving the life of the DC link capacitor, and also increasing the stability of the system.

[0066] The first power conversion unit (121) includes a plurality of first power conversion units connected in parallel, and the plurality of first power conversion units (121) can each be connected to a PV module. The control unit (130) can individually control the plurality of first power conversion units so that the input power follows the first power according to the characteristics of the PV modules connected to each of the plurality of first power conversion units. Alternatively, the control unit (130) can include a plurality of control units that respectively control the plurality of first power conversion units, and each control unit can individually control each first power conversion unit.

[0067] The power conversion unit (120) can be connected to a plurality of PV modules. The plurality of PV modules can be connected in series, in parallel, or in series-parallel. The control unit (130) can control the power conversion unit (120) so that the power output from all of the plurality of PV modules follows the first power.

[0068] The power conversion unit (120) can convert the power input from the PV module (210) into second AC power. The power conversion unit (120) can be a DC-AC inverter and can convert the power input from the PV module (210) into second AC power. At this time, the control unit (130) can control the power conversion unit (120) so that the DC power of the input terminal of the power conversion unit (120), which is an inverter, follows the first power.

[0069] Figures 10 to 15 illustrate various embodiments of a power conversion device according to an embodiment of the present invention.

[0070] As shown in Fig. 10, a sensing unit (110) is arranged at an input terminal of a power conversion unit (120) that receives and converts power from a PV module (210) to sense voltage (V_pv) and current (I_pv) and transmit them to a control unit (130). The power conversion unit (120) can supply power to a grid or a load (211). The control unit (130) can receive a first power (P_ref) and control the power conversion unit (120) so that power according to the voltage (V_pv) and current (I_pv) follows the first power (P_ref). Control that follows the first power can be referred to as IPPT.

[0071] As shown in Fig. 11, the power conversion unit (120) may be a DC-DC converter (123), and the power output from the DC-DC converter (123) may be supplied to the grid / load (221) via a DC link, and the control unit (130) may receive the first power (P_ref) and control the DC-DC converter (123) so that the power according to the voltage (V_pv) and the current (I_pv) follows the first power (P_ref).

[0072] As shown in Fig. 12, the power conversion unit (120) may be a DC-AC inverter (124), and the power output from the PV module (210) may be converted by the DC-AC inverter (124) via a DC link and supplied to the grid / load (221). The control unit (130) may receive the first power (P_ref) and control the DC-AC inverter (124) so ​​that the power according to the voltage (V_pv) and the current (I_pv) follows the first power (P_ref).

[0073] As shown in Fig. 13, the power conversion unit (120) may include a DC-DC converter (123) and a DC-AC inverter (124). Power output from the DC-DC converter (123) may be converted by the DC-AC inverter (124) via a DC link and supplied to the grid / load (221). The control unit (130) may receive the first power (P_ref) and control the DC-DC converter (123) and the DC-AC inverter (124) so ​​that power according to the voltage (V_pv) and the current (I_pv) follows the first power (P_ref). The control unit (130) receives the first power (P_ref), controls the DC-DC converter (123) so that the power according to the voltage (V_pv) and current (I_pv) follows the first power (P_ref), and controls the DC-AC inverter (124) so ​​that the DC link voltage is maintained constant.

[0074] As shown in Fig. 14, the power conversion unit (120) can be connected to a plurality of PV modules (211 to 214). The plurality of PV modules can be connected in series (211 and 212, 213 and 214), connected in parallel (211 and 213, 212 and 214), or connected in series and parallel. The control unit (130) can control the power conversion unit (120) so that the power output from all of the plurality of PV modules (211 to 214) follows the first power.

[0075] The first power conversion unit (121) includes a plurality of first power conversion units connected in parallel, and the plurality of first power conversion units (121) can be respectively connected to PV modules. As shown in Fig. 15, the first power conversion unit is a DC-DC converter (123, 124), and a PV module (215, 216) can be respectively connected to each of the DC-DC converters (123, 124). The second power conversion unit can be an inverter (124), and the plurality of DC-DC converters (123, 124) can be respectively connected in parallel and connected to the inverter (124). The control unit (130) can individually control the plurality of DC-DC converters (123, 124) so ​​that the input power follows the first power according to the characteristics of the PV modules (215, 216) connected to each of the plurality of DC-DC converters (123, 124).

[0076] In addition, the control unit (130) may include a plurality of control units that control a plurality of first power conversion units and a plurality of second power conversion units, and each control unit may individually control each of the first power conversion units and the second power conversion units.

[0077] As described above, by controlling the power conversion unit to follow the primary power, it is possible to precisely control the PV module to output the target power within its output range, making it easy to manage the power and energy of the entire system. In addition, since it can quickly control to the target power even in situations where the weather changes rapidly or the PV output amount changes, the stress on the passive components in the system can be reduced, thereby increasing its lifespan. In addition, since the output power can be controlled according to each situation when there are multiple input channels, high power generation efficiency can be achieved even when the input voltage range of each channel is varied. Even if only one channel has a lower maximum voltage than the other channels, it can be controlled accordingly, and since the power of each channel can be controlled individually, it is easy to manage heat generation of the entire system. Furthermore, when using a DC / DC converter and a DC / AC inverter together, PV module power control is possible at a lower DC-link voltage compared to other technologies, thereby increasing the efficiency of the entire system.

[0078] Those skilled in the art will appreciate that the present invention can be implemented in modified forms without departing from the essential characteristics of the above-described description. Therefore, the disclosed methods should be considered illustrative rather than restrictive. The scope of the present invention is set forth in the claims, not the foregoing description, and all differences within the scope equivalent thereto should be construed as being encompassed by the present invention.

Claims

1. A power conversion unit that converts and outputs power input from a PV module; A sensing unit that senses the voltage and current of the input terminal of the power conversion unit; and A power conversion device including a control unit that controls the power conversion unit so that the power according to the voltage and current of the input terminal of the power conversion unit sensed by the sensing unit follows the first power.

2. In paragraph 1, The above control unit, A power conversion device that controls the voltage of the PV module to be higher than the voltage of the maximum power point of the PV module.

3. In paragraph 1, A power conversion device that controls the voltage of the PV module to be lower than the voltage of the maximum power point of the PV module.

4. In paragraph 1, The above first power is a power conversion device that is the target output power of the power conversion unit.

5. In paragraph 1, The above power conversion unit supplies output to the grid, The above first power is a power conversion device that is power that can be supplied to the grid.

6. In paragraph 1, The above power conversion unit supplies output to the load, The above first power is a power conversion device that is the power required by the load.

7. In paragraph 1, The above first power is, A power conversion device that generates power based on power information received from the upper controller.

8. In paragraph 1, The above power conversion unit, A first power conversion unit that converts power input from the PV module into first DC power; A second power conversion unit that converts the first DC power into first AC power; and A power conversion device including a DC link connected between the first power conversion unit and the second power conversion unit.

9. In paragraph 8, The above control unit, A power conversion device that controls the first power conversion unit so that the output power of the PV module follows the first power, and controls the second power conversion unit so that the second power conversion unit outputs the first power.

10. In paragraph 8, The first power conversion unit includes a plurality of first power conversion units connected in parallel, The above plurality of first power conversion units are power conversion devices each connected to a PV module.

Images