KR100922537B1 - Power management system of renewable energy - Google Patents

Abstract

The present invention relates to a power management system of renewable energy that enables economic and efficient execution of power conversion of renewable energy regardless of the amount of renewable energy produced.

The renewable energy power management system includes n renewable energy sources (n is a natural number); N + k (k is a natural number) power converters for converting a DC voltage from the renewable energy source into an AC voltage; N first line parts connected to each output part of the renewable energy source, n + k second line parts connected to each of the input parts of the power converter and intersect the first line parts, and the first line A power management unit including n × (n + k) switch units formed at an intersection of the units and the second line units; And a controller for controlling driving of the switches.

Description

Power Management System of Renewable Energy {POWER MANAGEMENT SYSTEM OF RENEWABLE ENERGY}

The present invention relates to a power management system for renewable energy, and more particularly, to a power management system for renewable energy, which enables economic and efficient power conversion of renewable energy regardless of the amount of renewable energy produced.

Recently, in order to secure energy resources and overcome global warming, development and utilization of renewable energy have been actively conducted.

Renewable energy includes solar, solar, wind, and fuel cells.

These renewable energies are used directly as individual power sources, but they are also sold through the sales process into the grid.

The grid voltage used in the grid is alternating voltage, but renewable energy is often developed as direct voltage. Therefore, in order to supply renewable energy developed by DC voltage to the grid, the renewable energy must be converted into AC voltage. In addition, when renewable energy is directly used as individual power, there is a case where a DC voltage needs to be converted into an AC voltage as needed.

1 is a diagram showing a basic unit of a power conversion system for converting a DC voltage of renewable energy into a grid voltage of an alternating voltage, and shows a renewable energy source 10, a power converter 20, and a grid network 30. It is shown.

The renewable energy source 10 generates a DC voltage from the renewable energy, and the power converter 20 converts the DC voltage from the renewable energy source 10 into an AC voltage and supplies it to the grid network 30.

In the renewable energy power conversion system of the related art, the renewable energy source 10 and the power converter 20 are configured to have the same number, and are connected to each other by 1: 1 driving. Therefore, in the conventional renewable energy power conversion system, when the magnitude of the DC output voltage from the renewable energy source 10, that is, the amount of renewable energy is reduced, the magnitude of the voltage output by the alternating current through the power converter 20 is also increased. As the output of renewable energy increases, the AC output voltage also increases. For this reason, in the conventional power conversion system, when the amount of renewable energy is rapidly increased and is not included in the rated range of the power converter 20, the operation of the power conversion system has to be stopped, thereby causing a problem of waste of renewable energy. . In addition, in the conventional power conversion system, when the amount of renewable energy is less than the rated range of the power converter 20 and economical power generation is impossible, power is not interrupted in order to continuously maintain the renewable energy power generation. Since the converter 20 is continuously driven, there is a problem in that the life of the power converter 20 is shortened.

Accordingly, it is an object of the present invention to provide a power management system of renewable energy that enables economic and efficient execution of power conversion of renewable energy regardless of the amount of renewable energy produced.

In order to achieve the above object, the power management system of renewable energy according to an embodiment of the present invention is n renewable energy sources (n is a natural number); N + k (k is a natural number) power converters configured to convert a DC voltage from the renewable energy source into an AC voltage; N first line parts connected to each output part of the renewable energy source, n + k second line parts connected to each of the input parts of the power converter and intersect the first line parts, and the first line A power management unit including n × (n + k) switch units formed at an intersection of the units and the second line units; And a controller for controlling driving of the switches.

The first line portion includes an output line connected to an output of the renewable energy source, the second line portion includes an input line connected to an input of the power converter, and the switch portion includes the output line and the input. A switch formed at the intersection of the lines.

The first line portion includes a positive output line connected to an anode of the renewable energy source output portion; And a negative output line connected to the negative electrode of the renewable energy source output unit.

The second line unit includes a positive input line connected to the anode of the power converter input unit; And a negative input line connected to the negative electrode of the power converter input unit.

The switch unit may include a first switch formed at an intersection of the (+) output lines and the (+) input lines; And a second switch formed at an intersection of the (−) output lines and the (−) input lines.

The control unit transmits communication data including unique addresses of the switch units and on / off commands to the power management unit using any one of wired communication, wireless communication, and optical communication.

The control unit directly transmits an on / off command to the switch units.

The controller controls the switch units such that the renewable energy sources and the power converters are connected 1: 1.

The control unit controls the switch units such that i (natural number) renewable energy sources of the renewable energy sources and j (natural number of i ≠ j) of the power converters are connected to each other.

The switch unit includes a solid state switch or a solid state switch.

In the power management system according to the embodiment of the present invention, since the connection between the renewable energy source and the power converter is controlled by a switch unit arranged in a matrix form, the connection between the desired renewable energy source and the desired power converter is made through simple switching. Can be controlled. Therefore, in the case of low renewable energy production, the renewable energy sources can be connected in parallel to the power converters, and the power converters can be cooperatively operated for the renewable energy sources with high renewable energy yields. Power conversion of renewable energy can be performed economically and efficiently.

In addition, according to the present invention, the average operation time of the power converter is reduced through parallel operation to increase the life of the power converter, and the power converter may be repaired or replaced or the performance of the power converter may be evaluated even while the power management system is being driven.

Other objects and advantages of the present invention in addition to the above object will be apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2 to 7.

2 is a view showing a power management system of renewable energy according to an embodiment of the present invention.

2, a power management system of renewable energy according to an exemplary embodiment of the present invention includes a renewable energy unit 100, a power management unit 200, a controller 300, and a power converter 400. . Power generated through the power management system according to an embodiment of the present invention can be supplied to the grid 500, it can also be used as individual power.

The renewable energy unit 100 includes n (n is a natural number) renewable energy sources E ₁ to E _n . Renewable energy sources E ₁ to E _n generate direct voltage using solar, solar, wind, fuel cells, and the like.

The power converter 400 includes n + k (k is a natural number) power converters P ₁ to P _{n + k} . The power converters P ₁ to P _{n + k} convert the DC voltage generated by the renewable energy unit 100 into an AC voltage. Each power converter P ₁ to P _{n + k} includes a maximum power point tracking (“MPPT”) controller and an injection current controller to perform power conversion.

The power management unit 200 is connected to each of the n first line units 210 connected to each of the output units of the renewable energy sources E ₁ to E _n and the input units of the power converters P ₁ to P _{n + k} . N + k second line parts 220 and n × (n + k) switch parts 230 formed at the intersection of the first line parts 210 and the second line parts 220. do.

That is, in the embodiment of the present invention, k power converters (P _{n + k} ) are further included as a margin as compared to the related art, and renewable energy sources (E ₁ to E _n ) and power converters (P ₁ to P _{n + k) are included.} The switch unit 230 for controlling the connection of the) is arranged in a matrix form.

The first line portion 210 and the second line portion 220 include at least one line, and the switch portion 230 is generated due to the lines included in the first and second line portions 210 and 220. And as many switches as there are intersections. For example, when the first and second line portions 210 and 220 each include one line, the switch portion 230 includes one switch because the cross portion generated in the switch portion 230 is one. When the first and second line units 210 and 220 each include two lines, the switch unit 230 includes two switches.

In FIG. 2, a power management system used in a non-isolated grid 500 that does not connect the grid voltage to the ground is shown as an embodiment. Thus, the first line 210 renewable energy source (E ₁ to E _n), the (+) output line 211 and the renewable energy source (E ₁ to E _n) output of the cathode connected to the output of the anode And a negative output line 212 connected to it. In addition, the second line 220 is a power converter (P ₁ to P _{n + k),} the (+) input line 221 and the power converter (P ₁ to P _{n + k),} the cathode of the input unit connected to the anode of the input section And a negative input line 222 connected to it. Accordingly, the switch unit 230 may include a first switch 231 formed at an intersection of the (+) output line 211 and the (+) input line 221, and the (−) output line 212 and (−). A second switch 232 formed at an intersection of the input line 222.

On the other hand, although not shown, when a line of the grid is grounded in the grid 500, the (+) line and the (-) line are not required separately, so in this case, the first line portion 210 is one. It includes only the output line of, and the second line unit 220 also includes only one input line. Therefore, the switch unit 230 includes one switch formed at the intersection of the output line and the input line.

The switch may be a stationary power contactless switch such as a motor-driven or manually operated contact switch or a silicon controlled rectifier (SCR) switch. Among them, the SCR switch has advantages of large overcurrent resistance, high reliability, and small voltage drop. The SCR switch is turned on upon receiving a small current stimulus in the form of a pulse, and is turned off when the current flowing through the SCR switch reaches zero. Therefore, when the SCR switch is used, the SCR switch is turned on by supplying a small current stimulus in the form of a pulse as a gate signal at a desired time of turn-on. When the SCR switch is desired to be turned off, the supply of the gate signal is stopped and the magnitude of the DC input voltage of the power converter P ₁ to P _{n + k} connected to the SCR switch is changed to the renewable energy source E ₁ to E _n. Increase above the allowable voltage level. This current causes the renewable energy source (E ₁ to E _n) in as no longer a current does not flow, the renewable energy source (E ₁ to E _n), the current in the SCR switch, the supply of the output voltage because the 0 from The SCR switch is turned off.

The control unit 300 supplies the power management unit 200 with an on / off command of the switch unit 230 according to the amount of renewable energy production using a computer. In addition, the controller 300 continuously checks and stores voltages generated and used in the power management system, including the amount of renewable energy production, and analyzes operation data of the power management system by date, month, year, and the like. Evaluate the operating performance of each device.

The controller 300 may directly transmit the on / off command of the switch unit 230 to the switch units 230 or may transmit the communication unit through the communication network. The communication data transmitted through the communication network includes the unique addresses of the switch units 230 and the on / off command to enable the on / off control of the switch units 230 at a desired position. Communication methods include wired communication, wireless communication, and optical communication. The control unit 300 controls the switching of the switch units 230 through an automatic command and also controls the switching of the switch units 230 manually in an emergency.

Through the above method, the controller 300 controls the driving of the switch units 230 arranged in the matrix form in the power management unit 200 to generate renewable energy sources E ₁ to E _n and power conversion units P ₁ to. P _{n + k} ) can be controlled to a desired state. That is, on / off of the switch units 230 such that the renewable energy sources E ₁ to E _n and the power converters P ₁ to P _{n + k} are connected 1: 1 by the control of the controller 300. May be set, or may be set to be connected to i (natural number): j (natural number of i ≠ j).

Various driving examples by the controller 300 of the power management system shown in FIG. 2 are briefly shown in FIGS. 3 to 7.

First, FIG. 3 is a diagram showing an individual operation. Individual operation is an operation method when the output power of each of the renewable energy sources E ₁ to E _n is included within the rated range of the allocated power converters P ₁ to P _{n + k} . have. That is, as in the prior art, the switch unit 230 is controlled such that the renewable energy sources E ₁ to E _n and the power converters P ₁ to P _{n + k} are connected 1: 1. Therefore, in this case, the extra _{k of the} power converters P ₁ to P _{n + k} are not driven, and the DC voltage output from each of the renewable energy sources E ₁ to E _n is converted to each power converter P. Power conversion is achieved by an independent MPPT controller and injection current controller of ₁ to P _{n + k} ).

4 is a diagram illustrating parallel operation. Parallel operation is an operation method in which the amount of renewable energy production decreases, and when two or more renewable energy sources E ₁ to E _n are connected in parallel to each other, the parallel renewable energy sources E ₁ to E _{n are} connected. This is a method of connecting to a smaller number of power converters P ₁ to P _{n + k} . For example, a 2 to 4 renewable energy source, the yield decreased as shown in (E _1, E ₂₎ and the power converter (P ₁₎ if the output of the renewable energy reduced to half of the normal output: 1 connection with The switch unit 230 is controlled to be. If the amount of renewable energy is less than the normal output even if it is more than half of the normal output, three renewable energy sources E ₁ to E _n having similar characteristics are applied to the two power converters P ₁ to P _{n + k} . The switch unit 230 may be controlled to be connected. In the case of parallel operation, renewable energy sources E ₁ to E _n commonly connected to the same power converters P ₁ to P _{n + k} are subjected to power conversion by a common MPPT controller and injection current controller.

In the parallel operation using the SCR switch, the SCR switch turn-off method of the controller 300 will be described. First, the controller 300 blocks all the gate signals supplied to the SCR switch. The output current from the renewable energy sources E ₁ to E _n is reduced by gradually increasing the DC input voltage magnitudes of the power converters P ₁ to P _{n + k} . At this time, the SCR switch having the lower generated energy among the renewable energy sources E ₁ to E _n commonly connected to one power converter P ₁ to P _{n + k} is first turned off. Renewable energy sources E ₁ to E _n separated by the turn-off of the SCR switch may be relocated and used in other power converters P ₁ to P _{n + k} . Thereafter, to turn off the remaining SCR switches, the DC input voltage of the power converters P ₁ to P _{n + k} is further increased.

Through such parallel operation in the power management system according to an embodiment of the present invention economical development is possible by connecting the renewable energy sources (E ₁ to E _n ) in parallel even when the production of renewable energy is reduced, It has the advantage of reducing the average operating time of the power converter (P ₁ to P _{n + k} ) to increase its life.

5 is a diagram showing cooperative driving. The cooperative operation is an operation method in which the amount of renewable energy increases and exceeds the rated range of the power converter, and the one or more renewable energy sources E ₁ to E _n are replaced with the renewable energy sources E ₁ to E _n. ) Is placed in more power converters P ₁ to P _{n + k} . For this cooperative operation, the power conversion system according to an embodiment of the present invention further includes _k power converters P _{n + k} . In the case of cooperative operation, the power generated from the renewable energy sources E ₁ to E _n is placed in groups in a plurality of grouped power converters P ₁ to P _{n + k} to provide a common MPPT controller and injection current for each group. Power conversion is made by the controller. In this case, when the total power output of the renewable energy sources E ₁ to E _n exceeds the total rated capacity of the power converters P ₁ to P _{n + k} installed in the power management system, the power output may be exceeded. The operation of renewable energy sources E ₁ to E _n that produce as much power as possible is stopped.

In the power management system according to the embodiment of the present invention through such cooperative operation, even when the production of new and renewable energy increases rapidly, a new and renewable energy source (C1 through Pn _{+ k} ) is operated through cooperative operation of a plurality of power converters (P ₁ to P _{n + k} ). Continuous power generation is possible by converting the output voltage from E ₁ to E _n ).

6 is a diagram illustrating maintenance operation. The maintenance operation is an operation method in which some of the power converters P ₁ to P _{n + k} have failed, repaired or replaced, and a renewable energy source connected to the power converter P ₂ having a problem as shown in FIG. 6. It is a method of connecting (E ₂ ) to a power converter (P _{n + k} ) for a surplus during the time when repair or replacement work for the trouble-producing power converter P ₂ is performed. Therefore, such maintenance operation enables maintenance and replacement of the power converters P ₁ to P _{n + k} even during power generation of the power management system.

7 is a diagram illustrating an evaluation operation. Evaluation Driving power converter (P ₁ to P _{n + k)} performance driving method for the evaluation of the evaluation target power converter (P ₁ to P _{n + k)} and the power converter of the redundancy (P ₁ to P _{n + k} ) To compare performance. There are two types of evaluation drive. First, the first method is a method of cooperatively driving the power converter P ₂ and the spare power converter P _{n + k} to evaluate performance as shown in FIG. 7. That is, the power source P ₂ and the spare power converter P _{n + k} are commonly connected to the same renewable energy source E ₂ and then input of the two power converters P ₂ and P _{n + k} . Check the performance difference by comparing the voltage with the output voltage. The second method alternates power converters (P ₁ to P _{n + k} ) and spare power converters (P ₁ to P _{n + k} ) to evaluate performance on the same renewable energy source (E ₁ to E _n ). It is a method of checking the difference in performance by connecting and comparing the input voltage and the output voltage with each other. If these two checks do not fit within the established normal range, the power converter (P ₁ to P _{n + k} ), which is identified as a problem, is carefully examined and repaired or replaced. In the performance evaluation, each of these methods may be used by only one method, or both methods may be used in a certain order. Such evaluation operation can be carried out while maintaining power generation, thereby improving the operation efficiency of renewable energy sources.

As described above, in the power management system according to the embodiment of the present invention, in which the connection of the renewable energy source and the power converter is controlled by the switch unit of the matrix type, the renewable energy is generated regardless of the amount of renewable energy produced through simple switching. Power conversion can be performed economically and efficiently.

In addition, the present invention can increase the lifespan of the power converter by reducing the average operating time of the power converter through the parallel operation, it is possible to repair, replace and evaluate the performance of the power converter even during the operation of the power management system.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is a simplified diagram of a conventional power conversion system.

2 is a diagram illustrating a power management system according to an embodiment of the present invention.

3 is a diagram illustrating an individual operation of the power management system shown in FIG.

4 is a diagram illustrating parallel operation of the power management system shown in FIG.

5 is a view showing cooperative operation of the power management system shown in FIG.

FIG. 6 is a diagram illustrating maintenance operation of the power management system shown in FIG. 2; FIG.

FIG. 7 is a diagram showing an evaluation operation of the power management system shown in FIG. 2; FIG.

<Brief description of symbols for the main parts of the drawings>

10: renewable energy source 20: power converter

30, 500: grid 100: renewable energy department

200: power management unit 210: first line unit

211: (+) output line 212: (-) output line

220: second line portion 221: (+) input line

222: (-) input line 230: switch unit

231: first switch 232: second switch

300: control unit 400: power conversion unit

Claims (10)

n renewable energy sources (n is a natural number); N + k (k is a natural number) power converters configured to convert a DC voltage from the renewable energy source into an AC voltage; N first line parts connected to each output part of the renewable energy source, n + k second line parts connected to each of the input parts of the power converter and intersect the first line parts, and the first line A power management unit including n × (n + k) switch units formed at an intersection of the units and the second line units; And Control unit for controlling the driving of the switches Renewable energy power management system comprising a. According to claim 1, The first line portion includes an output line connected to an output portion of the renewable energy source, The second line portion includes an input line connected to an input portion of the power converter, The switch unit includes a switch formed at an intersection of the output line and the input line. Renewable Energy Power Management System. The method of claim 1, wherein the first line portion, A positive output line connected to an anode of the renewable energy source output unit; And (-) Output line connected to the negative electrode of the renewable energy source output unit Renewable energy power management system comprising a. The method of claim 3, wherein the second line portion, A positive input line connected to an anode of the power converter input unit; And (-) Input line connected to the negative electrode of the power converter input unit Renewable energy power management system comprising a. The method of claim 4, wherein the switch unit, A first switch formed at an intersection of the (+) output lines and the (+) input lines; And A second switch formed at an intersection of the (-) output lines and the (-) input lines Renewable energy power management system comprising a. According to claim 1, The control unit transmits communication data including unique addresses of the switch units and on / off commands to the power management unit by using any one of wired communication, wireless communication, and optical communication. Power management system. According to claim 1, The control unit is a renewable energy power management system, characterized in that for directly transmitting to the switch unit. According to claim 1, The controller controls the switch unit such that the renewable energy sources and the power converters are connected 1: 1. According to claim 1, The control unit controls the switch units such that i (natural number) renewable energy sources of the renewable energy sources and j (natural number of i ≠ j) of the power converters are connected to each other. Power management system of renewable energy. According to claim 1, The switch unit is a renewable energy management system including a solid state switch or a contact switch.

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