JP6231900B2 - Photovoltaic power generation facility for grid connection - Google Patents

Description

  The present invention relates to a grid interconnection solar power generation facility that converts DC power generated by a solar cell array into AC power and then supplies it to a distribution line of a distribution system.

  The grid-connection solar power generation facility that converts the DC power generated by the solar cell array into AC power and supplies it to the distribution system is configured, for example, as shown in the single-line diagram shown in FIG. In FIG. 2, 1 is a high-voltage distribution line of 6,600V, 2 is a solar cell array, 3 is a power conditioner including an inverter that converts a DC voltage output from the solar cell array 2 into a commercial-phase three-phase AC voltage. (PCS) 4, auxiliary machine 5, and circuit breaker (MCCB) 6 for stopping energization of auxiliary machine 5 when an overcurrent and an accident current flow through the energization circuit to auxiliary machine 5 It is a power conditioner panel that is housed and configured inside. The auxiliary machine 5 is an auxiliary device including a blower that cools the power conditioner 4 and a lighting device that illuminates the interior of the panel.

  Reference numeral 10 denotes an interconnection transformer that boosts the three-phase AC voltage output from the power conditioner 4 to the voltage of the high-voltage distribution line 1 and is configured by housing the step-up transformer 11 in the tank 12 together with the insulating medium. .

  The secondary side of the step-up transformer 11 is connected to the high-voltage interconnection panel 15. The high-voltage interconnection panel 15 includes a three-phase circuit breaker 16 inserted between the secondary side of the grid interconnection transformer 10 and the three-phase high-voltage distribution line 1, and the circuit breaker 16 from the transformer 10 side. A current transformer (CT) 17 that detects the current that flows in, and when an overcurrent is detected from the output of the current transformer 17, a shut-off command is given to the circuit breaker 16 after a certain period of time, and a short circuit occurs from the output of the current transformer 17 A protective relay (OCR) 18 that immediately gives a break command to the breaker 16 when a current is detected is housed in a metal case 19.

  In the illustrated example, a vacuum switch (VCB) is used as the circuit breaker 16, and when an accident current flows through the circuit between the power conditioner panel 3 and the high voltage interconnection panel 15, the accident current is distributed. In order to prevent injection into the electric wire 1, the circuit breaker 16 is opened, and the step-up transformer 11 and the circuit connected to the primary side thereof are disconnected from the high-voltage distribution line 1.

  In FIG. 2, reference numeral 25 denotes an auxiliary machine power supply panel that applies a power supply voltage to the auxiliary machine in the power conditioner board 7. The auxiliary machine power supply panel 25 shown in the figure has an auxiliary machine transformer 26 that steps down the output voltage of the step-up transformer 11 and one end connected to the primary terminal of the auxiliary machine transformer 26, and inputs to the auxiliary machine transformer 26. A three-phase load switch (LBS) 27 that opens and closes and a circuit breaker (MCCB) 28 that opens and closes the secondary current of the auxiliary transformer 26 are accommodated in a case 29. In the illustrated example, the load switch 27 is composed of a high voltage cutout switch with a high voltage fuse built in the movable contact, and when an overcurrent and an accident current flow through the circuit in the auxiliary machine power panel 25. The fuse provided in the movable contact is melted to disconnect the auxiliary transformer 26 and the secondary circuit from the high-voltage distribution line 1.

  Although it is conceivable to connect the primary side of the auxiliary transformer 26 to the output end of the power conditioner, if the primary side of the auxiliary transformer 26 is connected to the output end of the power conditioner, the auxiliary conditioner is connected to the auxiliary machine. Since a large load current flows to the transformer side, the loss increases, which is not preferable. In contrast, if the primary side of the auxiliary transformer 26 is connected to the secondary side of the step-up transformer 11 as described above, the load current flowing through the auxiliary transformer 26 can be reduced. Loss can be reduced.

  A facility having a configuration similar to that of the grid-connected photovoltaic power generation facility shown in FIG. 2 is disclosed in Patent Document 1, for example. Further, for example, Patent Document 2 shows that the power conditioner requires an auxiliary device such as a blower for cooling the power conditioner 4 and a lighting fixture for illuminating the inside of the panel.

JP 2013-544484 A JP 2013-143809 A

  In the conventional photovoltaic power generation facility shown in FIG. 2, in addition to the interconnection transformer 10, an auxiliary machine 26 is configured such that an auxiliary machine transformer 26 is housed in a case 29 together with a load switch 27 and a wiring circuit breaker 28. Since the power supply panel 25 is provided, there is a problem in that the number of panels provided in the power generation facility increases, and the configuration of the solar power generation facility becomes complicated. In addition, a load switch 27 is provided in the auxiliary machine power panel 25 to disconnect the auxiliary transformer 26 from the system when an accident occurs, and an overcurrent flowing through the secondary circuit of the auxiliary transformer is cut off. Since the circuit breaker 28 for wiring is provided, it is inevitable that the number of parts increases and the cost increases.

  The purpose of the present invention is to reduce the number of panels constituting the power generation equipment by omitting the conventionally required auxiliary power supply panel, and to provide a circuit breaker for disconnecting the step-up transformer from the system. The number of parts can be reduced by sharing the circuit breaker for disconnecting and sharing the circuit breaker provided in the inverter cabinet as the circuit breaker for interrupting the overload current of the auxiliary transformer. An object of the present invention is to provide a grid-connected solar power generation facility that can simplify the configuration and reduce the cost.

  The present invention relates to a power conditioner including an inverter that converts a DC voltage output from a solar cell array into an AC voltage having a commercial frequency, and a booster that boosts the AC voltage output from the power conditioner to a voltage of a distribution system connected to the power conditioner. A transformer, an auxiliary transformer that outputs a power supply voltage to an auxiliary machine including a blower that transforms a voltage on the secondary side of the step-up transformer and cools the power conditioner, and a secondary side of the step-up transformer and the power distribution A connection breaker inserted between the distribution lines of the system, a connection current detector for detecting a current flowing into the connection breaker, and a current detected by the connection current detector are set values. A connection protection relay that gives a disconnection command to the connection breaker when it is above, and a wiring break that cuts off the overload current when an overload current flows to the secondary side of the auxiliary transformer For grid connection with It is intended for photovoltaic equipment.

  In the present invention, in order to achieve the above object, the step-up transformer and the auxiliary transformer are accommodated in a common tank to constitute an interconnected transformer with an auxiliary power function. Also, the power conditioner, auxiliary equipment, and circuit breaker are housed in a common case to form a power conditioner panel, and the current that flows from the secondary side of the step-up transformer to the primary side of the auxiliary transformer Auxiliary transformer primary current detector, and a protective relay for disconnecting the auxiliary transformer that gives a disconnection command to the interconnection breaker when the auxiliary transformer primary current detector detects a current exceeding the set value Are housed in a common case together with the interconnection breaker, the interconnection current detector, and the interconnection protection relay to constitute a high voltage interconnection panel. In the present invention, the interconnection breaker also serves as a switch for disconnecting the auxiliary transformer from the distribution line when a current exceeding the set value flows into the auxiliary transformer.

  According to the present invention, the step-up transformer that boosts the AC voltage output from the power conditioner to the voltage of the power distribution system, and the auxiliary transformer that supplies the power supply voltage to the auxiliary machine in the power conditioner panel. Since the step-up transformer with auxiliary power supply function is configured in a common tank, it is possible to reduce the number of panels provided in the facility by omitting the auxiliary power supply panel that has been required conventionally.

  Further, according to the present invention, the circuit breaker for disconnecting the step-up transformer from the system is shared as a switch for disconnecting the auxiliary transformer from the system, and the circuit breaker provided in the power conditioner panel is supplemented. Since it is shared as a circuit breaker for cutting off the overload current of the machine transformer, the number of parts can be reduced and the cost can be reduced.

It is the single line connection figure which showed the structure of embodiment of this invention. It is the single line connection figure which showed the structure of the conventional grid connection photovoltaic power generation equipment.

  FIG. 1 is a single-line connection diagram showing a configuration example of a grid interconnection photovoltaic power generation facility according to the present invention. In the figure, reference numeral 1 denotes a high-voltage distribution line of 6,600V, and 2 denotes a solar cell array configured by further arranging a plurality of solar cell modules configured by arranging solar cells vertically and horizontally. The solar cell array 2 is generally installed in a place where a plurality of solar cell arrays 2 are provided and the sunshine conditions are good.

  3 is a power conditioner (PCS) 4, an auxiliary machine 5, and a circuit breaker (MCCB) that stops energization of the auxiliary machine 5 when an overcurrent and an accident current flow through the energization circuit to the auxiliary machine 5. 6 is a power conditioner panel constructed by housing 6 in a metal case 7 maintained at the ground potential. The power conditioner 4 removes harmonics from the chopper that boosts the DC voltage output from the solar cell array 2, the inverter that converts the DC voltage boosted by the chopper into a three-phase AC voltage of commercial frequency, and the output of the inverter. It is a well-known thing provided with the filter etc. which do. The power conditioner panel 3 further accommodates a control device for controlling the power conditioner 4 so as to keep the output voltage of the solar cell array at a voltage at which the maximum output can be taken out. Has been.

  The case 7 of the power conditioner panel 3 includes positive and negative DC input terminals 3 a connected to the input terminals of the power conditioner 4, and three-phase AC output terminals 3 b connected to the AC output terminal of the power conditioner 4. A three-phase AC input terminal 3c connected to the auxiliary machine 5 through the wiring breaker 6 is attached, and the DC output of the solar cell array 2 is supplied to the power conditioner 4 through the DC breaker 8 and the DC input terminal 3a. Have been entered. The auxiliary machine 5 is an auxiliary device (equipment other than the power conditioner) including a control device that controls the power conditioner 4, a blower that cools the power conditioner 4, a lighting device that illuminates the interior of the panel, and the like. .

  In FIG. 1, reference numeral 30 denotes an interconnection transformer with an auxiliary power supply function, which boosts a low-voltage AC voltage of 100 V or 200 V output from the power conditioner 4 to a voltage (6600 V) of the high-voltage distribution line 1 of the interconnection system. A step-up transformer 11 and an auxiliary transformer 26 that transforms the voltage on the secondary side of the step-up transformer 11 and outputs a power supply voltage (100 V in this example) to the auxiliary device in the power conditioner panel 3. It is configured by being housed together with an insulating medium in a common tank 31. In order to reduce the installation area of the interconnection transformer 30 with the auxiliary power supply function, the step-up transformer 11 and the auxiliary transformer 26 are not arranged side by side, but on the step-up transformer 11. Are preferably arranged so that the iron core of the auxiliary transformer 26 is mechanically supported by the iron core of the step-up transformer 11.

  In the present embodiment, the AC circuit in the power generation facility is almost a three-phase circuit, and both the step-up transformer 11 and the auxiliary transformer 26 are three-phase transformers. A primary bushing terminal 30a connected to the three-phase primary terminal, a three-phase secondary bushing terminal 30b connected to the three-phase secondary terminal of the step-up transformer 11, and a three-phase primary terminal of the auxiliary transformer 26. A total of 12 bushing terminals, that is, a three-phase primary bushing terminal 30c connected to the primary terminal and a three-phase secondary bushing terminal 30d connected to the three-phase secondary terminal of the auxiliary transformer 26 are attached. ing. The bushing terminal has an insulating bushing attached in a state of penetrating the tank 30, a through conductor penetrating through the center of the insulating bushing, and a terminal portion provided at one end and the other end of the through conductor, respectively. belongs to.

  The primary bushing terminal 30a connected to the primary side of the step-up transformer 11 of the interconnection transformer 30 with auxiliary power supply function is connected to the output terminal 3b of the power conditioner panel 3 through the connection conductor C1, and the interconnection transformer with auxiliary power supply function is provided. The secondary bushing terminal 30d connected to the secondary side of the auxiliary transformer 26 of the capacitor 30 is connected to the input terminal 3c of the power conditioner panel 3 through the connection conductor C2.

  In FIG. 1, 40 is a high-pressure interconnection board. This high-voltage interconnection panel is for an interconnection breaker 16 that is inserted between the secondary side of the step-up transformer 11 and the distribution line 1 of the distribution system, and for detecting the current flowing into the interconnection breaker 16. A current detector 17, a connection protection relay 18 that gives a disconnection command to the connection breaker 16 when the current detected by the connection current detector 17 is equal to or greater than a set value, and a step-up transformer 11. Auxiliary transformer primary current detector 41 that detects a current flowing from the secondary side to the primary side of auxiliary transformer 26 and an interconnection when the auxiliary transformer primary current detector 41 detects a current greater than a set value. The auxiliary transformer disconnection protection relay 42 that gives a break command to the breaker 16 is housed in a common metal case 43 that is kept at the ground potential.

  The case 43 has an input terminal 40a connected to one end of the circuit breaker 16 through the connection conductor 44, an output terminal 40b connected to the other end of the circuit breaker 16, and an output connected to the input terminal 40a through the connection conductor 45. A terminal 40c is attached. The input terminal 40a is connected to the output terminal 30b of the interconnection transformer 30 through the connection conductor C3, and the AC voltage output from the step-up transformer 11 is connected through the output terminal 30b, the connection conductor C3, the input terminal 40a, and the connection conductor 44. It is input to one end of the system breaker 16. The output terminal 40c is connected to the primary bushing terminal 30c of the interconnection transformer 30 through the connection conductor C4. The secondary side of the step-up transformer 11 is the output terminal 30b, the connection conductor C3, the input terminal 40a, the connection conductor 45, The output terminal 40c, the connection conductor C4, and the primary side bushing terminal 30c are connected to the primary side of the auxiliary transformer 26.

  The current transformer 17 in the high voltage interconnection panel 40 is provided so that the connection conductor 44 is a primary side through conductor, and detects a current flowing through the circuit breaker 16 when the circuit breaker 16 is in an ON state. The output terminal 40b to which the other end of the interconnection breaker 16 is connected is connected to the interconnection point of the high-voltage distribution line 1 through the connection conductor C5.

  Also in this embodiment, the circuit breaker 16 consists of a vacuum switch (VCB). The circuit breaker 16 opens when the fault current flows through the circuit between the circuit breaker 16 and the power conditioner panel 3 and the protective relay 18 generates a circuit break command, and disconnects the step-up transformer 11 from the distribution line 1. . The circuit breaker 16 is also opened and compensated when an accident occurs in the circuit from the connection conductor 45 through the auxiliary transformer 26 to the auxiliary machine 5 in the power conditioner panel 3 and the protective relay 42 generates a cutoff command. The machine transformer 26 is disconnected from the distribution line 1.

  As described above, the step-up transformer 11 that boosts the AC voltage output from the power conditioner 4 to the voltage of the power distribution system, and the auxiliary transformer that supplies the power supply voltage to the auxiliary machine 5 in the power conditioner panel. Are installed in a common tank 31 to constitute the step-up transformer 30 with auxiliary power supply function, and the auxiliary power supply panel 25 required in the conventional power generation equipment shown in FIG. The number of boards can be reduced, and the area required for installing the boards can be reduced.

  Further, as described above, the circuit breaker 16 that disconnects the step-up transformer 11 and its primary circuit from the system is shared as a switch that disconnects the auxiliary transformer 26 and its load circuit from the system. In addition, if the wiring breaker 6 provided in the power conditioner panel is shared as a wiring breaker that cuts off the overload current of the auxiliary transformer 26, the number of parts is reduced and the cost is reduced. be able to.

DESCRIPTION OF SYMBOLS 1 High voltage distribution line 2 Solar cell array 3 Power conditioner panel 4 Power conditioner 5 Power conditioner auxiliary equipment 6 Circuit breaker 7 Case 11 Step-up transformer 16 Interconnection breaker 17 Interconnection current detector 18 Interconnection Protective relay 26 Auxiliary transformer 30 Auxiliary transformer with power supply function 31 Tank 40 High voltage interconnection panel 41 Auxiliary transformer primary current detector 42 Auxiliary transformer disconnection protective relay

Claims (1)

A power conditioner including an inverter that converts a DC voltage output from the solar cell array into an AC voltage of commercial frequency, and a step-up transformer that boosts the AC voltage output from the power conditioner to a voltage of a distribution system connected to the power conditioner; An auxiliary transformer that outputs a power supply voltage to be supplied to an auxiliary machine including a blower that transforms a voltage on the secondary side of the step-up transformer to cool the power conditioner, a secondary side of the step-up transformer, and the An interconnection breaker inserted between the distribution lines of the distribution system, an interconnection current detector for detecting a current flowing into the interconnection breaker, and a current detected by the interconnection current detector A protective relay for interconnection that gives an interruption command to the interconnection breaker when a set value is exceeded, and wiring that cuts off the overload current when an overload current flows to the secondary side of the auxiliary transformer With circuit breaker for In the photovoltaic power generation facilities for system interconnection,
The step-up transformer and the auxiliary transformer are housed in a common tank to form an interconnected transformer with an auxiliary power function,
The power conditioner panel is configured by accommodating the power conditioner, the auxiliary machine, and the wiring breaker in a common case,
Auxiliary transformer primary current detector for detecting current flowing from the secondary side of the step-up transformer to the primary side of the auxiliary transformer, and the auxiliary transformer primary current detector detects a current greater than a set value. The auxiliary transformer disconnection protection relay that gives a disconnection command to the interconnection breaker when the interconnection breaker, the interconnection current detector, and the interconnection protection relay are common Housed in a case to form a high-pressure interconnection panel,
The interconnection breaker also serves as a switch that disconnects the auxiliary transformer and its secondary circuit from the distribution line when a current greater than a set value flows into the auxiliary transformer. A featured solar power generation facility.

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