DE102012023424B4 - Energy distribution system with a control device - Google Patents

Abstract

Energy distribution system with a control device (5),
to which at least one electrical energy source (10) and at least one electrical energy store (11) can be connected,
the voltage converter (7, 8, 9), which convert the energy from the source (10) and the energy storage (11) fed into a single- or multi-phase AC voltage whose voltage level and frequency is such that the AC voltage to supply a local Installation (3) and for feeding into a power supply network (1) is suitable, and from the voltage of the power source (10) generate a voltage for charging the energy store (11),
wherein the local installation (3) via a switching device (20) with the power supply network (1) ("network operation") or with one of the energy from the energy source (10) and / or energy storage (11) from the voltage transformers (7, 8, 9) generated alternating voltage ("island operation") is connectable,
wherein the voltage transformers (7, 8, 9) include a single inverter (7), which in the network operation feeds energy into the power supply network (1) as the power source and supplies the local installation (3) as a voltage source in isolated operation,
wherein in network operation, the switching device (20) connects the local installation (3) to the power supply network (1) and a circuit breaker (30) connects the output of the inverter (7) with the
Power supply network (1) connects,
wherein in island operation the switching device (20) connects the local installation (3) to the output of the inverter (7) and the disconnecting switch (30) disconnects the output of the inverter (7) from the power supply network (1),
wherein the switching device (20) consists of a first and a second controllable electromechanical switch (21, 22), which are locked against each other against simultaneous switching,
wherein the circuit breaker (30) consists of a third and a fourth controllable electromechanical switch (31, 32) which are controlled in parallel, and that to form switch contacts of the circuit breaker (30) normally open contacts of the third and fourth circuit breaker (31, 32) in Are connected in series,
characterized,
in that the first and second controllable electromechanical switches (21, 22) of the switching device (20) are repeatedly locked against each other against simultaneous switching on.

Description

The invention relates to an energy distribution system with a control device according to the preamble of claim 1.

Such an energy distribution system is known from the German patent application DE 10 2010 000 502 A1 known.

The patent document US 2011/0 148 205 A1 discloses an energy distribution system with a control device to which at least one electrical energy source and at least one electrical energy storage is connectable, the voltage converter which convert the voltages fed from the energy source and the energy storage voltages in a single- or multi-phase AC voltage whose voltage level and frequency is such in that the AC voltage is suitable for supplying a local installation and for feeding into a power supply network, and that generate a voltage for charging the energy store from the voltage of the energy source, the local installation being connected via a switching device to the power supply network ("mains operation") or one of the energy from the energy source and / or energy storage of the voltage transformers generated AC voltage ("island operation") is connectable, and wherein the voltage transformers include a single inverter, which in network operation al s power source feeds energy into the power grid and supplies the local installation as a voltage source in isolated mode.

A power distribution system may in particular be connected to a regenerative energy source, and then forms a part of, for example, a photovoltaic or a wind turbine. The following explanation relates purely by way of example and without limiting the general public to a photovoltaic system.

Photovoltaic systems for the at least supportive energy supply of buildings are becoming increasingly widespread. The electrical output of a photovoltaic generator is subject to fluctuations over the course of the day and therefore practically never exactly corresponds to the instantaneous energy consumption of the consumers installed in the building, which are referred to in the following as a local installation as a local installation.

Thus, a photovoltaic system can generate an electric power during the light hours of the day, which goes far beyond the electrical power requirements of the local installation, so that excess electrical energy can be fed into a public power grid. In the rest of the time it may be necessary to remove electrical energy from the public power supply network to compensate for energy shortages.

Photovoltaic systems with a so-called self-consumption optimization have accumulators as energy storage, which can store several kilowatt hours of electrical energy. The supply or removal of electrical energy from the public power grid takes place here only when the buffering capacity of the energy storage is exceeded or if this is due to daytime electricity tariffs profitable.

From the German patent application DE 101 62 955 A1 An arrangement for the energy management of an uninterruptible power supply is known. The arrangement is connected to a power supply network and also has a generator and a DC storage. The arrangement operates in various modes in which a load is supplied either from the power grid, through the generator or through the DC storage, or is fed into the power grid at the power generated by the generator. To make this possible, the arrangement has two independent inverters. One of these inverters, referred to in the document as a grid-parallel inverter, operates as a power source and feeds power into the power grid. Its tension follows the tension of the net. A second inverter serves as a voltage source and, in the event of a power failure, supplies the load from the voltage of the generator or DC storage.

In this document, an inverter is also mentioned, which can operate in different modes as a current or voltage source. However, such an inverter, which can change its operating mode, is described in this document as dangerous, because such a design, a voltage can be switched to the power supply network while it is turned off and is maintained. This can endanger persons who work on the alleged de-energized network.

Energy distribution systems, which have several inverters for realizing different operating modes, however, have a relatively complex structure and are therefore relatively expensive.

It set itself the task to create an energy distribution system, on the one hand a simple and inexpensive construction, but on the other hand guarantees a high level of security.

This object is achieved in that the first and second controllable electromechanical switch of the switching device are repeatedly locked against each other against simultaneous switching.

For the operation of the power distribution system, two possible modes are provided, namely, first, the operation with coupling to the power supply network, referred to herein briefly as network operation, and secondly the decoupled from the power supply operation, which is named here as island operation. The island operation allows in a power failure operation of consumers of a local installation over a period of time from the energy of a generator and / or an energy storage.

The invention provides at least one circuit breaker which can safely disconnect the output of the single inverter from the power supply network, and a switching device which connects the local installation either to the power supply network or to the output of the inverter.

Both the circuit breaker and the switching device are formed by controllable electromechanical switch, which connect or disconnect said compounds all poles. In a preferred embodiment, both the circuit breaker and the switching device are realized by two independently controllable contactors.

For a particularly safe operation, it is advantageous if the simultaneous switching on certain electromechanical switch is excluded (locked). The locking can, as will be explained in more detail below, done by mechanical or electrical means. It is particularly advantageous to provide a plurality of independently acting locking types and to combine them.

The sole use of electromechanical switches can lead to a short-term (on the order of about one second) interruption of the voltage supply of the local installation when switching between mains and island operation, which is acceptable to most consumers. The invention expressly dispenses with the provision of a completely uninterruptible power supply in favor of a simple structure and high reliability.

In the following, the invention will be explained in more detail with reference to an embodiment shown in the drawing. The 1 to 3 each show in the form of a block diagram of the structure of an energy distribution system, the electrical energy to supply a local installation, which may be given by the entirety of the electrical systems and consumers of a building, provides and can also feed electrical energy into a public power grid. The 4 explains in a circuit diagram various possibilities for locking electromechanical switches.

Central element of the 1 to 3 shown power distribution system is a control device 5 to which a solar generator 10 and an energy store 11 can be connected. The solar generator 10 consists of a variety of, not shown here in detail, photovoltaic modules, which in turn each have a plurality of solar cells. The solar generator 10 converts radiant energy of the sun into electrical energy, whereby the emitted electrical power can vary in the course of the day depending on the momentary incidence of light.

To better match the power output of the power distribution system to the needs of local installation 3 adapt, is the energy storage 11 is provided, which preferably consists of an interconnection of accumulators with a total capacity in the order of several kilowatt hours. The energy storage 11 can by the solar generator 10 discharged electrical energy to be charged. In addition, he can at times when the power requirements of the local installation 3 The output power of the solar generator 10 exceeds, compensate for the lack of performance. Both the solar generator 10 as well as the energy storage 11 is inside the control device 5 one DC / DC converter each 8th . 9 assigned to those from the solar generator 10 or the energy storage 11 delivered voltages to that for feeding into the public power grid 1 bring required voltage level. The output voltages of the DC / DC converters 8th . 9 be from a DC / AC converter 7 , the following as an inverter 7 is designated in one to supply the local installation 3 or for feeding into the power supply network 1 converted suitable multi-phase AC voltage. The DC / DC converter 9 is bidirectional to charge the energy storage 11 from the output voltage of the DC / DC converter 8th to enable.

The output voltage of the inverter 7 is on an output line 18 led, which has a solar energy meter 4 with a Connection node 16 the main line 15 is interconnected. The solar energy meter 4 is used to determine the from the solar generator 10 and the energy storage 11 in the local installation 3 or the power supply network 1 supplied amount of energy.

Into the main 15 connecting the public power grid 1 and the local installation 3 is a bidirectional measuring electronic energy meter 2 looped in, both from the public power grid 1 as well as those in the public power supply network 1 entered amount of energy detected.

The output of the inverter 7 is also with a backup line 17 connected to the switching contacts of an electromechanical switch 22 a switching device 20 leads. In the backup line 17 are also switching contacts of a residual current relay 14 inserted. The residual current relay 14 is through the control device 5 switched on and interrupts the backup line in case of fault currents occurring during island operation 17 automatically. In mains operation, the circuit breaker 30 used for a residual current cut-off.

The in the 1 to 3 simplified illustrated alternating current and voltage leading lines 15 . 17 . 18 comprise in addition to a neutral all belonging to the power distribution system phase conductors and are therefore designed four-wire for the usual three-phase voltage networks.

The control device 5 has sensors 12 . 13 for several electrical quantities, including at least the voltage U on the output line 18 and the output current I of the inverter 7 , The current sensor 12 and the voltage sensor 13 give their output signals to inputs of a microcontroller, not shown here, as part of the control device 5 the inner and outer processes of the control device 5 controlled. The current sensor 12 is intended for fault current detection, that is, when the sum of all the currents flowing through it are not equal to zero, becomes a measurement signal for driving the residual current relay 14 generated.

The control device 5 controls in particular a switching device 20 on which two controllable electromechanical switches 21 . 22 , designed as contactors or relays, as well as one in the output line 18 switched disconnector 30 , which consists of at least two electromechanical switches 31 . 32 consists of series-connected switch contacts. The number of poles of the electromechanical switches 21 . 22 . 31 . 32 corresponds at least to the number of conductors of the cables connected to it 15 . 17 . 18 so the switches 21 . 22 . 31 . 32 the wires 15 . 17 . 18 disconnect or connect to each other.

The 1 shows the power distribution system in an inactive state in which only the closed switch 21 the switching device 20 the local installation 3 with the power supply network 1 combines. The desk 22 the switching device 20 , as well as the switches 31 and 32 of the disconnector 30 are not driven and therefore open, so the control device 5 and with it the photovoltaic generator 10 and the accumulator 11 completely off the main line 15 are separated. This mode is rather uncommon and may be at a fault of the control device 5 , the photovoltaic generator 10 or the accumulator 11 be provided as emergency mode.

The 2 illustrates as the standard mode of operation of the network operation of the power distribution system. The circuit breaker 30 is closed here, so that the output of the inverter 7 now over the counter 4 at the connection node 16 the main line 15 connected.

In mains operation, the inverter behaves 7 like a power source; Mains voltage and mains frequency are supplied by the power supply network 1 imprinted. In this respect, a control or regulation of the mains voltage and mains frequency is not required and not at all possible. The task of the inverter 7 is it, its output current I in phase to the mains voltage profile in the power supply network 1 feed. Depending on the requirements of the grid operator, the inverter must 7 also reactive power in the power supply network 1 can feed, so that between the mains voltage and the output current I can set a phase shift.

The 3 should clarify the island operation of the power distribution system, in which the consumers of the local installation 3 completely independent of the power supply network 1 operate. For island operation, the local installation must be done 3 completely from the power supply network 1 be disconnected because in case of failure of the generating units in the power grid 1 the at the power supply network 1 remaining loads (outside the local installation 3 ) the output voltage of the inverter 7 otherwise short circuit.

This complete separation is firstly through the open circuit breaker 30 causes the main 15 from the output of the inverter 7 separates and secondly by the switching of the two coupled switches 21 . 22 the switching device 20 , About the closed switch 22 the switching device 20 as well as the closed Contacts of the residual current relay 14 is the local installation 3 in island mode directly to the output of the inverter 7 turned on.

In island operation, the inverter is 7 operated as a voltage source, which means that grid voltage and grid frequency is now from the inverter 7 be managed. Only the same amount of power is needed in the local installation 3 fed, that sets the desired voltage curve in the respective load situation.

To meet legal requirements and beyond safety requirements, it is advantageous or even necessary, the electromechanical switch used 21 . 22 . 31 . 32 on the one hand perform redundant and on the other hand, to avoid false control, the simultaneous switching on certain combinations of switches 21 . 22 . 31 . 32 to exclude by a lock.

In the power distribution system according to the invention according to the 1 to 3 is particularly a locking of the mutually switching switch 21 and 22 the switching device 20 provided. It is particularly advantageous, these switches 21 . 22 as contactors, which have a mutual mechanical switch-lock.

A lock against common switching should also for the disconnector 30 and the residual current relay 14 be provided.

The two switches 31 . 32 of the disconnector 30 Although always switch on and off together, but are by the control device 5 independently controlled in order to ensure a high degree of reliability through full redundancy. An advantageous possibility for functional testing of such a circuit breaker 30 is in the non-prepublished German patent application DE 10 2012 018 411 A1 explained.

4 shows is to illustrate the principle of multiple locking of controllable switches against simultaneous switching. Sketchy illustrated are two electromechanical switches R1 . R2 , which are executable as a relay or contactors, each of which several working contacts K1 . K2 respectively. The working contacts shown here unconnected K1 . K2 are used in an energy distribution system for separating and connecting phase and neutral conductors.

In addition, each switch has R1 . R2 at least one normally closed contact CC1 . CC2 , via which the drive voltage U + the other switch R2 . R1 is guided. The control of the switches R1 . R2 via a control contact SK1 . SK2 in series with the normally closed contact CC2 . CC1 the other switch R2 . R1 is switched. The control contacts SK1 . SK2 are as changeover contacts of an auxiliary relay MR executed, which by the control device 5 is controlled. The control contacts SK1 . SK2 cause, depending on the control state of the auxiliary relay MR only one of the two switches R1 . R2 with the drive voltage U + connected is.

Through the switching control contacts SK1 . SK2 This results in a first locking of the switch R1 . R2 already with the control by the auxiliary relay. A second lock the switch R1 . R2 is achieved by that of a controlled switch R1 . R2 open normally closed contact CC1 . CC2 the tightening of the other switch R2 . R1 prevented. This second lock is also effective when the first lock by the control contacts SK1 . SK2 should fail due to a technical defect.

As a further measure, a mechanical lock can be provided. In spatially juxtaposed switches R1 . R2 causes a forced coupling M the switching mechanisms that only one of the two switches R1 . R2 can be in the on state.

The switches R1 . R2 to lock against each other, so a common activation of certain switches R1 . R2 To prevent this, it is necessary for a correct and safe functioning of a power distribution system.

It is particularly advantageous switch R1 . R2 lock against each other several times, so that occurring errors can not lead to safety-critical conditions. By double or even triple locking of switches so a single-fault security or even beyond security level can be achieved.

LIST OF REFERENCE NUMBERS

1

Power supply network

2

Energy meter (bidirectional)

3

local installation

4

Solar energy meters

5

control device

6

phase conductor

7

Inverter (DC / AC converter)

8th

DC / DC converter

9

DC / DC converter (bidirectional)

7, 8, 9

DC converter

10

Photovoltaic generator (generator)

11

Accumulator (energy storage)

12

current sensor

13

voltage sensor

12, 13

sensors

14

Fault current relays (contacts)

15

main

16

Connection node

17

backup line

18

output line

15, 17, 18

cables

20

switching

21, 22

(electromechanical) switches

30

disconnectors

31, 32

(electromechanical) switches

MR

auxiliary relay

I

output current

K1, K2

make contacts

M

Mechanical lock

R1, R2

(electromechanical) switches

SK1, Sk2

control contacts

U

output voltage

U +

driving voltage

VK1, VK2

NC contacts

Claims (9)

Energy distribution system with a control device (5), to which at least one electrical energy source (10) and at least one electrical energy store (11) can be connected, the voltage converter (7, 8, 9), that of the energy source (10) and the energy storage (11) converted voltages into a single- or multi-phase AC voltage whose voltage level and frequency is such that the AC voltage for supplying a local installation (3) and for feeding into a power supply network (1) is suitable, and from the voltage of Energy source (10) generate a voltage for charging the energy store (11), wherein the local installation (3) via a switching device (20) to the power supply network (1) ("network operation") or one of the energy from energy source (10) and / or energy storage (11) of the voltage transformers (7, 8, 9) generated AC voltage ("island operation") is connectable, wherein the voltage w (7, 8, 9) a single inverter (7) is included, which feeds power in the network operation as power in the power supply network (1) and the local installation (3) supplies in island operation as a voltage source, wherein in the network operation, the switching device (20 ) connects the local installation (3) with the power supply network (1) and a circuit breaker (30) connects the output of the inverter (7) to the power supply network (1), wherein in island operation, the switching device (20) the local installation (3) the output of the inverter (7) connects and the disconnector (30) the output of the inverter (7) from the power supply network (1) separates, wherein the switching device (20) consists of a first and a second controllable electromechanical switch (21, 22), which are locked against simultaneous switching against each other, wherein the circuit breaker (30) of a third and a fourth controllable electromechanical switch r (31, 32) which are controlled in parallel, and in that to form switch contacts of the circuit breaker (30) normally open contacts of the third and fourth disconnectors (31, 32) are connected in series, characterized in that the first and second controllable electromechanical Switch (21, 22) of the switching device (20) against simultaneous switching multiple times against each other are locked. Energy distribution system after Claim 1 , characterized in that in each case the control voltage (U +) of the first and the second controllable switch (21, 22, R1, R2) via one NC contact (VK2, VK1) of the second or first controllable switch (22, 21, R2 , R1). Energy distribution system after Claim 1 , characterized in that the switching mechanisms of the first and the second controllable switch (21, 22, R1, R2) by a mechanical locking device (M) are interconnected. Energy distribution system after Claim 1 , characterized in that a software and / or hardware implemented control logic driving the first or second controllable switch (21, 22, R1, R2) always together with a shutdown of the second or first controllable switch (22, 21, R2 , R1). Energy distribution system after Claim 4 , characterized in that the control logic by mutually switching control contacts (SK1, SK2) of an auxiliary relay (HR) is formed. Energy distribution system after Claim 1 , characterized in that in series with switching contacts of the second controllable switch (22) of the switching device (20), the switching contacts of a residual current relay (14) are connected. Energy distribution system after Claim 1 , characterized in that the electromechanical switches (21, 22, 31, 32, R1, R2) phase and neutral conductors disconnect and connect all poles. Energy distribution system after Claim 1 , characterized in that the energy source (10) is a photovoltaic generator. Energy distribution system after Claim 1 , characterized in that the energy store (11) is an electrical accumulator.

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