CN203352192U

CN203352192U - Direct current switch device

Info

Publication number: CN203352192U
Application number: CN2013202845499U
Authority: CN
Inventors: 不公告发明人
Original assignee: SMA Solar Technology AG
Current assignee: SMA Solar Technology AG
Priority date: 2013-05-23
Filing date: 2013-05-23
Publication date: 2013-12-18
Anticipated expiration: 2023-05-23

Abstract

The utility model provides a direct current switch device (40). By responding to a control signal provided by a control circuit (60), the direct current switch device breaks off the connection between at least one terminal of a photovoltaic generator (10) and an inerter (30); the direct current switch device comprises a first relay (43), a second relay (42) and a semiconductor switch component (44); and the first relay, the second relay and the component are controlled by a common control unit (41). The direct current switch device is characterized in that the first relay (43) and the semiconductor switch component (44) are arranged in different parallel current paths; the direct current switch device is used for responding to the control signal, and firstly, the control unit (41) is used for closing the semiconductor switch component (44), and then switching off the first relay (43) so as to allow current of a generator to pass through the semiconductor switch component (44) and then switching off the semiconductor switch component (44), so that the current of the generator can be largely or totally cut off, without arcs being generated, and then the second relay (22) is switched off.

Description

DC switchgear

Technical field

The utility model relates to a kind of for cutting off the DC switchgear of direct current, specifically, relates to and having for preventing or reduce the DC switchgear of photovoltaic plant of the thyristor of switching arc.

Background technology

Direct current relay is crossed the electric current of switch contact for interrupt flow.Relay comprises control coil, and by this control coil, the current direction metallic armature is to be attracted.This metallic armature mechanically is connected to one or more electric main contactss.Rely on magnetic force, main contacts is switched on or turn-offs, and this depends on that relay is configured to cut-out relay or circuit closing relay.Generally speaking, such relay is electric gate-controlled switch.

But there is the shortcoming that switching arc occurs in relay, particularly when cutting off direct current.This will temporarily cause high temperature and the high corrosion of switch contact.As a result, a plurality of switch contacts are easy to be welded together, and make them be attached to each other together and no longer can guarantee current interruptions.This phenomenon is called as " contact fusing ".Relay is usually only for being no more than the reduced-current of 30A.

Other tie breaker system that is applicable to photovoltaic plant is called as " electronic solar switch (ESS) " or has carried out at DE 102 25 259 B3 or in DE 10 2,004 054 933 B3 describing in more detail.ESS is placed on a DC line in two DC line.If operate machine switch, and the semiconductor switch connected will switch on and off continually.Thereby, prevent or reduced electric arc.Correspondingly, generally speaking ESS is the switch of hand-guided, and it has for eliminating the electron assistant effect of electric arc.The voltage that it is applicable to photovoltaic DC-to-AC converter and exceeds the electric current of 10A and exceed 100V.This ESS can only operate manually.

The utility model content

In aspect one of the present utility model, provide a kind of DC switchgear, it disconnects at least one terminal of photovoltaic generator (10) and being connected of inverter (30) for the response as to the control signal from control circuit.This device comprises the first relay, the second relay and thyristor, and each relay and element are controlled by common control unit.The first relay is arranged in different, parallel current path from thyristor.As the response to control signal, control unit is by the thyristor closure, disconnect subsequently the first relay, thereby make the dynamo current thyristor of flowing through, disconnect subsequently thyristor, thereby cut off in fact or fully dynamo current, and electric arc does not occur, and disconnect subsequently the second relay.Like this, realized providing in direct current for automatically cut off photovoltaic plant when fault occurs at least one in two current-carrying circuits the solution cheaply of electric current isolation.The second relay is connected with thyristor, and also can be positioned at the outside of described different, parallel current path.This device can be integrated in inverter inside, but also can be placed in the inverter outside, particularly approaches the position of photovoltaic generator.

In an embodiment of the present utility model, this device also comprises hand switch, as load cut-off device or connectors.This hand switch can have the arc-quenching system.In another modification, thyristor for example can be used as the use of arc-quenching system by the suitable control of control unit.This hand switch can be connected with the first relay.

Each relay can be controlled by control signal automatically by control unit, and there is no the risk of contact fusing.According to the utility model, effectively reduce or cut off electric current by thyristor, thereby making in relay can not switch electric arc.For another relay of electric current isolation, at the electric current reduced or while there is no electric current, start.The rated value of the relay therefore, used and corresponding cost can significantly reduce.Alternatively, thyristor can be periodically switched on and turn-off during the transition stage to its disconnection or closure.By this timing, can prevent stable electric arc, particularly in the direct voltage electrical network.

The advantage that the utility model combines the ESS solution and automatically closes.Thereby, do not have in handoff procedure or only have the electric arc that weakens to occur, thereby staff or power station can be not dangerous, and can transmit signal to the control unit of DC switchgear while breaking down.

In another aspect, the utility model is revised ESS operation design, its alter mode is that load current will no longer be interrupted by the mechanical inserted connector, and electronic device serves as the effect of electric arc quencher, but, for example, when the starting hand switch, only to control unit, give signal, described control unit is controlled shutoff operation subsequently.The starting of hand switch can be regarded as an event in the utility model.And, as the faults such as short circuit also can be considered as an event.

Control unit also can be carried out the overcurrent that is particularly useful for photovoltaic plant or the enabled condition in the short circuit current situation.Microprocessor for example can be used in control unit.Preferably, control unit is integrated in DC switchgear.

According to the utility model, in DC switchgear, can comprise extra can manually operated load cut-off device or ESS load cut-off device.By removing connectors or the protective cover with arc protection function, can manually disconnect DC circuit, and not rely on the control signal of control unit.

In order to improve the reliability of this device, the power supply that provides redundantly this device from AC and the DC side of inverter.

More details of the present utility model describe by example with reference to the accompanying drawings.

The accompanying drawing explanation

Fig. 1 shows the first structure as the DC switchgear of the part of photovoltaic plant;

Fig. 2 shows the second structure of DC switchgear;

Fig. 3 shows the 3rd structure of DC switchgear;

Fig. 4 shows the 4th structure as the DC switchgear of the part of photovoltaic plant.

Embodiment

Fig. 1 shows the first example as the DC switchgear 40 of the part of photovoltaic plant.DC switchgear 40 comprises two relays 42 and 43.Each relay comprises control coil, and this control coil has a switch contact or pair of contact.Two relay series connection.

Thyristor 44(is the IGBT switch particularly) in parallel with relay 43.

The part that DC switchgear 40 is DC circuit, this DC circuit has the DC line 20 between photovoltaic generator 10 and inverter 30.For photovoltaic generator 10 is connected to inverter 30, by two relays, 42,43 closures.Two relays have the dynamo-electric stream of specified maximum generation under closure state.

DC switchgear 40 comprises electronic control unit 41, and this electronic control unit 41 is connected with

relay

42,43, more specifically say with their control coil and be connected, thus can be by corresponding control

signal starter relay

42,43 automatically.Thyristor 44 is controlled by electronic control unit 41 equally.

When photovoltaic generator 10 will disconnect from inverter 30, in the first step, thyristor 44 closures.At second step, relay 43 disconnects, the relay 42 and the thyristor 44 that impel load current to flow through to be connected in series.In the 3rd step, thyristor 44 disconnects, and load current is disconnected, and do not form electric arc.In the 4th step, relay 42 disconnects.Thereby, realize the electric current isolation between photovoltaic generator 10 and inverter 30.Be in the situation that do not have electric current to disconnect due to relay 42, therefore can not form electric arc.When again photovoltaic generator 10 being connected to inverter 30, will carry out above-mentioned four steps with reverse order.

These steps are controlled by control unit 41, and

relay

42,43 and thyristor 44 are by control unit 41 operations.By control circuit 60, the signal that can be provided for being switched on or switched off.Can mistake, manual-lock order, external electrical instruction in overcurrent, overvoltage, excess Temperature, fire situation, device occur, install that lid is opened, during at least one event in common low pressure electric network fault, stolen these events of photovoltaic plant, provide cut-off signal.Can detect these events by independent electronic device or transducer.

For whether existing the estimation of certain event or fault to carry out or to be undertaken by external electronic unit (particularly by the element inverter 30 or electronic device) from control unit 41.All use control circuit 60 in both of these case.Optionally, some control circuits can be used for wanting the variety of event signal of parallel transmission.Also control circuit 60 can be embodied as to digital line or bus, as RS232 or CAN.Equally, DC switchgear 40 can be controlled and communication line transfers a message to other external electronic unit by control circuit 60 or another, thereby sends the signal of for example closing automatic generation and/or being successfully completed due to certain event or signal at stop.The error reason detected also can transmit by this circuit.

In addition, control unit 41 can be provided with the voltage supply line road 7 of preferred redundancy link, for example, can all provide to carry to DC side and AC to be connected.

Relay 42, or two

relays

42,43 preferably, the maximum voltage that there is specified DC circuit under off-state.Because

relay

42,43 can not cut out under loading condition, therefore can use and keep lower-powered relay.If load current can directly be closed, need to have the higher relay of specified maintenance power of higher master craftsman of the Spring and Autumn period's property.

As switching device optionally, a modification of the present utility model has been shown in Fig. 2.Extra hand switch 70(is ESS load cut-off device particularly) with relay 43, connect.Hand switch 70 can also be mechanical contact or connectors.By this modification, full automatic shutoff operation and whole manual shutoff operation can be realized.In manual operation, the energy that can produce by the electric arc in DC circuit is supplied voltage to ESS.The energy that extraly or optionally, can produce when disconnecting relay 43 is to ESS or control unit 41 supply voltages.Thereby, guarantee or even the situation of some assemblies under be separated from each other.

Also imagined the situation that the relay 42 shown in Fig. 2 is got rid of.Thereby ESS design is relaxed, for the demand of the switch circulation that meets larger quantity and do not change mechanically operated design.

Another modification of switching device has been shown in Fig. 3.Hand switch 70 is connected with relay 43, and thyristor 44 is connected with relay 42.The parallel connection of two groups of tandem tap devices.

Another embodiment has been shown in Fig. 4.Circuit in Fig. 1, the 3rd relay 45 is connected with corresponding another DC line that there is no relay in Fig. 1.Thereby, realized when

relay

42 and 45 disconnects the complete electric current isolation between photovoltaic generator 10 and inverter 30.Preferably, relay 45 is designed to carry full-load current.In the time of also can or approaching zero current at zero current due to the 3rd relay 45, switch, so it can be also less, the economic relay that only has lower allowed switch load.

Reference numerals list

10 photovoltaic generators

20 DC line

30 inverters

40 DC switchgears

50 alternating current circuits

41 control units

42,43,45 relays

44 thyristors

60 control circuits

70 hand switches

Claims

1. a DC switchgear (40), its control signal provided in response to control circuit (60) disconnects at least one terminal of photovoltaic generator (10) and being connected of inverter (30), this device comprises the first relay (43), the second relay (42), and thyristor (44), each in the first relay and the second relay and thyristor are controlled by common control unit (41), it is characterized in that: the first relay (43) is positioned at different from thyristor (44), in parallel current path, wherein, in response to described control signal, in the first step, the closed thyristor of control unit (41) (44), disconnect subsequently the first relay (43), thereby make the dynamo current thyristor (44) of flowing through, disconnect subsequently thyristor (44), thereby cut off in fact or fully dynamo current, and electric arc does not occur, and disconnect subsequently the second relay (42).

2. device as claimed in claim 1, is characterized in that, the second relay (42) is connected with thyristor (44).

3. device as claimed in claim 1, is characterized in that, the second relay (42) is positioned at the outside of described different, parallel current path.

4. device as claimed in claim 1, it is characterized in that, the 3rd relay (45) terminal different from of photovoltaic generator (10) connects, and is configured to disconnect in response to described control signal, so that the electric current isolation to be provided between photovoltaic generator (10) and inverter (30).

5. device as claimed in claim 1, it is characterized in that, described control signal represents at least one event in following event: mistake, manual-lock order, external electrical instruction in overcurrent, overvoltage, excess Temperature, fire situation, device, install that lid is opened, the common low pressure electric network fault and/or photovoltaic plant stolen.

6. device as claimed in claim 1, is characterized in that, this device is placed in the outside of inverter (30).

7. device as claimed in claim 1, is characterized in that, the power supply of this device is supplied redundantly by AC and the DC side of inverter (30).

8. device as claimed in claim 1, is characterized in that, this device also comprises hand switch (70).

9. device as claimed in claim 8, is characterized in that, hand switch (70) has the arc-quenching system.

10. device as claimed in claim 8, is characterized in that, hand switch (70) is connected with the first relay (43).