HK1230795B - Network node for a power network, variable transformer for a network node, and method for operating a network node - Google Patents

Description

The invention relates to a power supply network node, in particular a substation or local power station, a control transformer for a power supply network node and a method for operating a power supply network node.

The electricity network may be, for example, a grid, energy grid, power grid, electricity grid, power grid, power grid or electricity grid and may have, for example, one or more, in particular three phases and/or be structured as a ring grid, grid or grid-meshed grid.

DE 10 2011 005 837 A1 describes an electric power distribution network node for an electric power distribution network, which has a transformer 92 and an output module and is a local power station with a medium voltage switchgear suitable for connection to a ring cable of a medium voltage network. This document also describes a high voltage network connected to a medium voltage network via a power line. The medium voltage network is connected to a ring cable connecting local power stations to each other in an open ring network. This arrangement is connected to a low voltage local power connection via a transformer 60 wind turbine. The wind power station generates some wind power, which is transmitted to the medium voltage power station and fed into the ring cable.The two local service stations are each provided with a medium voltage switchgear to connect to the ring cable of the medium voltage network. A transformer 92 is connected to the medium voltage switchgear via a switch 91 which converts the medium voltage of the medium voltage network in the range 1 kV to 50 kV into a low voltage suitable for final customers or end-users of, for example, 220 V per phase. A low voltage distribution line is connected to the transformer 92 which has a variety of connections to supply the low voltage output of the transformer. The transformer 92 is equipped with three switches, one of which is a medium voltage field, to connect the first ring cable to the medium voltage field.a second ring-wire field for the output side of the ring-wire and a transformer field for the connection to switch 91 and thus the transformer 92. The medium-voltage switching system shall be equipped with two switching drives which operate on switches 90d and 90e of the medium-voltage switching system. The switching drives enable the respective assigned switch 90d and 90e to be switched on or off. Another switch drive shall turn on or off the switch 91.

DE 10 2012 103 490 A1 describes a local area voltage-control distribution transformer, having a main winding and a control winding with multiple winding contacts, a step-control device for uninterrupted switching between different winding contacts of the distribution transformer, with at least one switch contact unit with several fixed contacts electrically connected to each of the individual winding contacts arranged along a line, with the fixed switching contacts operated by two longitudinally moving switch contacts, with the switch contactless operation being provided for two single-phase switching, with at least one power supply operated by a single-phase power supply, with at least one power supply operated by a single-phase power supply in a common direction, and with at least one power supply for the rotation of the motor without interruption, and with at least one power supply for the rotation of the motor without interruption, and with the switch contactless operation being provided for two single-phase switching, with at least one power supply operated by a single-phase power supply in a vacuum-controlled direction, and with at least one power supply unit for the rotation of the motor without interruption, and with at least one power supply unit for the rotation of the motor without interruption of the power supply and the power supply, and the power supply of the motor without interruption of the switch.

EP 1 014 528 B1 describes an electrical transformer system comprising an electrical transformer with primary and secondary windings, a voltage-free switch, a load-switching electrical switch and connectors. The windings form a primary circuit with one or more primary phases fed over power lines and a secondary circuit with one or more secondary phases. The switch comprises fixed electrical contacts connected to the electrical windings. The switch comprises one or more movable bridge contacts with electrical connections between the specified contacts, which may be fixed accordingly. The switch may be mounted between the contacts moving in the first position and a second moving connection, which may be fixed accordingly. The contacts moving between the contacts may be moved between the first and the second contacts, and the contacts may be moved between the first and the second contacts, which may be fixed accordingly.The switch shall consist of an actuator capable of occupying at least one first position, one second position and a third position situated between the first and second positions. The switch shall consist of a kinematic chain arranged between the actuator and the switch such that the actuator, when moving from its first position to its second position, transfers the switch from its first position to its second position. The switch shall consist of a pole for each power supply line of the primary circuit which may occupy one shut-off position corresponding to a break in the current flow in the power supply line and one shut-off position corresponding to a flow in the power supply line. The switch shall consist of a power-driven actuator equipped with a switch-off mechanism,capable of passing from a high energy state to a stable low energy state and connected by a kinematic chain to each pole in such a way that, when passing from its high energy state to its low energy state, it moves the pole or poles from their starting position to their shutting position. The shutting mechanism shall comprise a latch which may be used to lock the shutting mechanism in its high energy state and a release position which allows the shutting mechanism to exit its higher energy state. The connecting devices shall be located between the actuator of the switch and the shutting mechanism's shutting mechanism,that when the actuator is moved from its initial position to its intermediate position, the latch is moved to its unlocking position.

DE 876 432 B describes a device for facilitating earth-disconnection in high voltage systems, whereby the voltage at the earth-disconnection is lowered in order to eliminate the disruption of the earth-disconnection caused by corona losses, reducing the voltage in the earth-disconnection in the manner known in step-transformers without interruption of the load current.

WO 2011 032 585 A1 describes a device to protect a local power transformer and a three-phase power line from a single-phase or phase-to-phase failure of the local power transformer. The device includes a protection device for the local power transformer/power line, a three-phase power interruption device, a zero current sensor and an interruption device for the interruption device. The interruption device is connected between the protection device for the local power transformer/power line and the local power transformer. In the case of a three-phase power transformer, the electrical circuit is directed to the electrical circuit for the final connection of the local power transformer/power line, which is a short circuit detector. In the case of a failure of the power detector, the electrical circuit is disconnected from the central power detector (in the case of a short circuit detector) and the electrical current is directed to the zero current in the direction of the failure.

Err1:Expecting ',' delimiter: line 1 column 205 (char 204)

The purpose of the invention is to create a power supply node, a control transformer for a power supply node and a method for operating a power supply node that allows for a lower load and wear of a protective switch for the control transformer, especially when triggered by grounding, short circuit or lightning.

The purpose of this task is to solve the problems of the independent claims.

The invention proposes, in a first aspect, a power grid node, having or including: a control transformer with a primary side and a secondary side;a primary or access line connected to the primary side;a secondary or output line connected to the secondary side;a protective switch located in the access line or output line;a sensor capable of detecting an electrical characteristic in the access line and/or output line and generating at least an appropriate measurement signal;a control device coupled to the control transformer, protective switch and sensor and designed to: it can control the control transformer in such a way as to have a predetermined and/or predeterminable and/or predeterminable and/or suitable translation ratio depending on the measurement signal;it can control the protective switch in such a way as to open it depending on the measurement signal; The control-operated opening of the protective switch shall be carried out as soon as or after the control transformer has reached the prescribed translation ratio.

The control transformer can, for example, reduce the current flowing through the protective switch which has not yet been triggered, i.e. closed, by setting an appropriate translation ratio, for example in the event of a failure event such as a grounding, short-circuit or lightning strike which can be detected by the control device by means of the sensor.

The proposed network node may be, for example, a substation connected primarily to a high voltage or high voltage network and secondarily to a high voltage or medium voltage network or a local service station connected primarily to a medium voltage network and secondarily to a low voltage network.

The proposed network node may be configured in any way as required, including or including at least one additional or additional control transformer and/or at least one additional or additional access line and/or at least one additional or additional output line and/or at least one additional or additional protective switch and/or at least one additional or additional sensor and/or at least one additional or additional control device. Preferably, an access line and an output line shall be provided for each phase of a three-phase AC network. If at least one additional or additional sensor is available, the control device shall preferably also be coupled to these and trained to control the control transformer depending on at least one measuring signal, which is transmitted from the measuring device coupled to the sensor and/or control device coupled to the sensor, and depending on the type of protection.

Each control transformer may be designed in any way as required, for example, in a single-phase or three-phase design and/or adjustable on its primary and/or secondary sides. It shall preferably include at least one control device to change or control the translation ratio and preferably at least one control winding with at least two taps connected to the control device on the primary and/or secondary sides. Each control device may include in particular at least one load step switch and/or at least one half-turn switch, in particular a power half-turn switch, and be coupled to the control unit. The network may be a control transformer if the control unit is a control station, for example, an ORTON or a control transformer.

For example, each control transformer may be trained as one of the control transformer proposed under the second aspect.

Each shield switch may be configured in any way as required, for example by including at least one load switch and/or at least one power switch; preferably, the network node shall include at least one shield switch device which includes at least one shield switch and also at least one trigger or actuator which can operate at least one shield switch and/or at least one of the sensors which is coupled to at least one of the actuators.

Each load switch and/or power switch may be configured in any way as required and may include, for example, at least one vacuum switch and/or at least one SF6 gas switch and/or at least one compressed air switch and/or at least one oil switch and/or at least one oil-poor switch and/or at least one semiconductor switch.

Each sensor may be trained in any way necessary to detect, for example, the current or voltage or phase shift or power or action or shift factor as an electrical parameter and generate a corresponding measurement signal.

Each control device may be designed in any way necessary, for example to ensure that the prescribed suitable transmission ratio corresponds to a prescribed or prescribed protection design; the protection design may be optional and/or arbitrary, for example as an overcurrent protection design, which reduces or avoids an excessive current in the line equipped with the respective protection switch, or an overvoltage protection design, which reduces or avoids an excessive voltage on the line equipped with the respective protection switch, or an undervoltage protection design, which avoids or increases an excessive voltage with the respective protection switch, or a combination of at least two of these.

In the case of a power surge protection design for the primary side or the access line, i.e. if a power switch is located in the access line, a suitable translation ratio may be, for example, greater than the current translation ratio and preferably the maximum translation ratio; if the current translation ratio should already be the maximum translation ratio, it may be the maximum translation ratio, since a larger translation ratio corresponds to a smaller current on the primary side.

In the case of a secondary or outlet circuit overcurrent protection design, i.e. if a protection switch is located in the outlet circuit, a suitable translation ratio may be, for example, smaller than the current translation ratio and preferably the minimum translation ratio; if the current translation ratio should already be the minimum translation ratio, it may be the minimum translation ratio, since a smaller translation ratio corresponds to a smaller current on the secondary side.

In the case of a surge protection design for the primary side or the access line, i.e. if a switch is located in the access line, a suitable translation ratio may be, for example, smaller than the current translation ratio and preferably the minimum translation ratio; if the current translation ratio should already be the minimum translation ratio, it may be the minimum translation ratio.

In the case of a surge protection design for the secondary side or the outlet line, i.e. if a protection switch is located in the outlet line, a suitable transition ratio may be, for example, greater than the current transition ratio and preferably the maximum transition ratio; if the current transition ratio should already be the maximum transition ratio, it may be the maximum transition ratio.

The appropriate translation ratio will preferably depend on the characteristics or characteristic parameters of the respective protective switch, for example, for a first protective switch with a first short-circuit current carrying capacity and a second protective switch with a second short-circuit current carrying capacity greater than the first short-circuit current carrying capacity, a first protective switch requiring a first time duration and a second protective switch requiring a second time duration greater than the first time duration may be suitable.

It may be provided that: The control device shall be so designed that the control of the protective switch is operated after the control of the control transformer.

The time interval between the control transformer and the protective switch shall preferably be at least equal to the control transformer switching time required, for example, by the control transformer when trained as a load switching step transformer to switch from one socket or step to an adjacent socket or step.

It may be provided that: the control device is designed to operate the shield before or simultaneously with the control of the control transformer;the shield is coupled to a delay device designed to delay the opening of the shield.

The delay device may be configured in any manner as required and, if the protective switch is operated by a relay, include, for example, a coil connected in series with the relay's originator coil and/or a capacitor connected in parallel with the relay's originator coil.

It may be provided that each of the proposed network nodes shall include: a voltage of not more than 50 V at least one of the protective switches located in the access line;two primary or access connections;two additional protective switches, each connecting one of the access connections to the end of the access line not connected to the primary side.

The access connections allow the network node to be integrated into an electricity network, for example, a ring or mains network.

Each additional protective switch may be configured in any way as required and include, for example, at least one load switch and/or at least one power switch and/or at least one switch and/or at least one load switch; each load switch may be, for example, a load switch or a vacuum switch which, due to the vacuum tube used, controls, for example, 10 short circuit switches and 10 short circuit switches at 1000 load switches.

It may be provided that each of the proposed network nodes shall include: at least one filter connected to the access line and/or the outlet line and including in particular a dynamic filter and/or an active filter; and/or at least one condenser bank connected to the access line and/or the outlet line; and/or at least one energy storage device connected to the access line and/or preferably the outlet line and including in particular an electrical energy storage device and/or a chemical energy storage device and/or a thermal energy storage device and/or a compressed air storage device.

Each of the proposed network nodes may, for example, be used to perform one of the proposed procedures and/or be trained and/or functional and/or capable of performing and/or performing one of the proposed procedures.

The invention proposes, in accordance with a second aspect, a control transformer for a power grid node, the power grid node being, in particular, like one of the power grid nodes proposed in accordance with the first aspect, comprising: primary side and a secondary side;a primary or access line connected to the primary side;a secondary or exit line connected to the secondary side;a protective switch located in the access line or exit line;a sensor capable of detecting an electrical characteristic in the access line and/or exit line and generating at least an appropriate measurement signal;a control device to change or adjust or control the translation ratio;a control device coupled to the control device, the protective switch and the sensor and designed to: it can control the control device according to the measuring signal so that the control transformer has a predetermined and/or predeterminable and/or predetermined and/or predeterminable and/or appropriate translation ratio;it can control the protective switch according to the measuring signal so that it opens; The control-operated opening of the protective switch shall be carried out as soon as or after the control transformer has reached the prescribed translation ratio.

The control device can, for example, reduce the current flowing through the protective switch which has not yet been triggered, i.e. closed, by setting an appropriate translation ratio, for example in the event of a failure event such as a grounding, short-circuit or lightning strike which can be detected by the control device by means of the sensor.

The proposed control transformer may be designed in any way as required, for example, with a single-phase or three-phase design and/or adjustable on its primary and/or secondary side. It shall preferably include at least one control winding on its primary and/or secondary side, each with at least two connecting taps, connected to the control device. Alternatively or additionally, it may include at least one additional or additional access line and/or at least one additional or additional outlet line and/or at least one additional or additional sensor switch and/or at least one additional or additional sensor node and/or at least one additional or additional control node and/or at least one additional or additional measurement or control signal, so that the control device or control device is designed to provide at least a double-phase protection, if the control device or sensor is installed in a control device, the protection and/or control signal may be so remote that the control device or control device is connected to the network and the voltage is controlled by a double-phase protection.

In particular, each access line may be at least part of one of the access lines of the network node. Each output line may in particular be at least part of one of the output lines of the network node. Each protective switch may in particular be at least part of one of the protective switches of the network node. Each sensor may in particular be at least part of one of the sensors of the network node. Each control device may in particular be at least part of one of the control devices of the network node. Each control device may in particular be at least part of one of the control devices of the network node.

Each control device may be configured in any way necessary, for example, to include at least one load-level switch and/or at least one semiconductor switch, in particular a power semiconductor switch.

It may be provided that each proposed control transformer includes: a voltage of not more than 50 V at least one of the protective switches located in the access line;two primary or access connections;two additional protective switches, each connecting one of the access connections to the end of the access line not connected to the primary side.

In particular, each overvoltage switch may be part of at least one of the overvoltage switches of the network node.

It may be provided that each proposed control transformer includes: a housing containing the active component of the control transformer and the control device; wherein the protective switch and/or the AC system is located in the housing.

This will allow for better use of space in the network node where such a control transformer is located.

This integration into the housing makes a particularly useful design, in which the switch unit of the load switch and the shield switches are closely connected in space, so that the drive for the load switch and the shield switch can be integrated into a single drive, and the control of all the switching units can be taken over by the control calculator of the load switch.

If the control transformer is designed as an oil transformer with an oil boiler, the housing may be, for example, the oil boiler.

It may be provided that: the control transformer contains inside it at least one temperature sensor capable of generating a temperature signal and/or at least one pressure sensor capable of generating a pressure signal;the control unit is coupled to each temperature sensor and/or pressure sensor and is so designed that: It shall be capable of operating at least one of the protective switches in such a way as to open it, depending on at least one of the temperature signals and/or at least one of the pressure signals.

This opening shall preferably be immediate or immediate or without delay.

The temperature sensor may, for example, include a bimetallic switch or a thermometer with a limiting trigger.

If the control transformer comprises a housing, the temperature and/or pressure sensors shall preferably be located in the housing.

The invention proposes, in accordance with a third aspect, a method for operating a power grid node, including the grid node, which is in particular designed as one of the grid nodes proposed in accordance with the first aspect. a control transformer with a primary side and a secondary side, specially designed to resemble one of the control transformer proposed under the second aspect;a primary or access line connected to the primary side;a secondary or output line connected to the secondary side;a protective switch located in the access line or output line; where at least one electrical parameter in the access line or the outlet line is monitored and/or measured and/or recorded;if at least one of the parameters meets a fault criterion, in step (a), the control transformer, in particular depending on at least one of the parameters, is controlled to have a predetermined and/or predeterminable and/or predetermined and/or predeterminable and/or suitable translation ratio, and in step (b), the protective switch, in particular depending on at least one of the parameters, is opened;the protective switch in step (b) is opened as soon as or after the control transformer has the predetermined translation ratio.

The control transformer can, for example, reduce the current flowing through the protective switch which has not yet been switched off, i.e. which is closed, by setting an appropriate translation ratio, for example, in the event of a failure event such as a grounding, short-circuit or lightning strike which can be detected by monitoring.

The proposed procedure may be designed in any way necessary, for example to ensure that the predetermined appropriate translation ratio corresponds to a predetermined or prescribed protection design; the protection design may be selectable and/or arbitrarily chosen as necessary, for example as a surge protection design or a surge protection design or a surge protection design or a combination of at least two of these protection designs.

The proposed procedure will, for example, allow the operation of one of the proposed network nodes.

Any electrical parameter may be chosen as desired, for example as the current or voltage or phase shift or power factor or power factor or displacement factor. The monitored parameters may be combined and evaluated in any way desired, for example to obtain, determine or calculate another parameter not directly monitored or measured or recorded. For example, the voltage may be determined from the two parameters current and phase shift as additional parameters.

The error criterion can be chosen as appropriate, for example to check whether the parameter is greater than a first threshold and/or its rate of change is greater than a second threshold.

It may be provided that: (c) a first control signal is sent to the control transformer in step (a); and/or (b) a second or first control signal is sent to the control switch in step (d).

It may be provided that: The following steps are followed:

It may be provided that: (d) is performed before or at the same time as step (c); in step (b) the opening of the shield is delayed.

It may be provided that: the temperature and/or pressure inside the control transformer is monitored; if the temperature and/or pressure meet a fault criterion, the protective switch is opened.

This opening shall preferably be immediate or immediate or without delay.

The terms and conditions of the invention shall be such that they are not subject to any limitation or restriction.

The following illustrations explain the embodiments of the invention in more detail. The individual features resulting from the embodiments are not, however, limited to the individual embodiments but may be combined and/or combined with the individual features described above and/or with individual features of other embodiments. The details in the drawings are intended to be illustrative only and not to be interpreted in a restrictive manner. The references in the claims are not intended to limit the scope of the invention in any way but merely to refer to the embodiments shown in the drawings. Figure 1a first embodiment of a network node integrated into a ring-shaped power grid;Figure 2a second embodiment of a power grid node comprising a preferred embodiment of a control transformer.

Err1:Expecting ',' delimiter: line 1 column 417 (char 416)

In this embodiment, the network node 10 shall comprise a control transformer 11 with a primary side and a secondary side, an access line 12 connected to the primary side, an output line 13 connected to the secondary side, a protective switch 14 located in the access line 12, a sensor 15 capable of detecting an electrical characteristic in the access line 12 and generating a measurement signal, a control device 16 coupled to the control transformer 11 , the protective switch 14 and the sensor 15, and a low voltage distribution device 22, which is an example of a low voltage distribution device.

Err1:Expecting ',' delimiter: line 1 column 252 (char 251)

The control transformer 11 is an example of an adjustable local power transformer, also known as a RONT, comprising an active component 26, a control device 18 to change the transmission ratio of the control transformer 11 and a housing 27 containing the active component 26 and the control device 18, the control device 18 is connected to the primary side of the active component 26 which comprises a non-displayed control winding with several taps for each phase of the power supply 19, coupled to the control device 16 for control purposes, and, for example, a load step switch.

The substation 22 shall comprise a multiple-connector bus 23 through which, for example, energy consumers such as households receiving low voltage from the network node 10 and/or energy generators such as photovoltaic and wind turbines can feed their generated electricity into the electricity grid 19.

The sensor 15 is an example of a current sensor and is designed as a current converter, so that it can measure the current in the access line 12 as a characteristic and generate a current signal as a measuring signal.

The control unit 16 is designed to control the control unit 18 and therefore the control transformer 11 depending on the current signal in such a way that the control transformer 11 has a suitable translation ratio corresponding to a given protection design and thus a predetermined suitable translation ratio, and that it can control the control switch 14 depending on the measurement signal in such a way that it opens, the opening of the control switch 14 being effected by the control as soon as or after the control transformer 11 has the appropriate translation ratio.

An example of a protection concept is a surge protection concept stored in the control unit 16 where the control unit 16 determines the maximum translation ratio as the appropriate translation ratio if the current translation ratio is the maximum translation ratio and, otherwise, the translation ratio as the appropriate translation ratio which is the next largest to the current translation ratio.

In this embodiment, the control device 16 is designed to operate the shield switch 14 simultaneously with the control of the control transformer 11 and the shield switch 14 is coupled to a delay device 28 designed to delay the opening of the shield switch 14 by a predetermined time interval. The shield switch 14 is operated, for example, by an unshielded relay, and the delay device 28 includes, for example, an unshielded coil that is connected in series with the relay actuator. The preset time is selected so that the control transformer 11 can be converted to the appropriate switching ratio.

A first embodiment of a process for operating a network node 10 for an electricity network 19 will be described below, where the network node 10 is an example of the network node 10 shown in FIG. 1.

In this embodiment, the current in the access line 12 is monitored, for example by means of the sensor 15 and the control unit 16. The monitoring is carried out, for example, by checking whether the current is greater than a threshold corresponding to the given overcurrent protection concept and thus a predetermined threshold and thus whether it meets a fault criterion.

If this test shows that this is the case, i.e. if the current meets the fault criterion, then in step (a) the control transformer 11 is controlled to the prescribed appropriate transition ratio and in step (b) the protective switch 14 is opened, e.g. by means of the control device 16.

In order to control the control transformer 11 in step (a), a first control signal is sent to the control device 18 and thus to the control transformer 11 in step (c), for example by means of the control device 16.

To open the shield switch 14 in step (b), a step (d) sends the first control signal to the shield switch 14 and executes step (d) simultaneously with step (c), for example by means of the control device 16.

In step (b), the opening of the protective switch 14 is delayed, for example by means of the deceleration device 28.

In Fig. 2 a second embodiment of a network node 10 for an electricity network 19 is shown schematically.

In this embodiment, the control transformer 11 is trained according to a preferred embodiment and the deceleration device 28 is eliminated.

The control transformer 11 comprises, for example, the access line 12, the output line 13, the protective switch 14, the sensor 15, the control device 16, the AC system 17, a temperature sensor 29 which can generate a temperature signal and a pressure sensor 30 which can generate a pressure signal. It is designed as an oil transformer and its housing 27 is a hermetically sealed oil boiler filled with oil and the access line 12, the sensor 15, the AC system 17, the temperature sensor 29 and the pressure sensor 30 are housed.

The control device 16 shall be coupled to the temperature sensor 29 and the pressure sensor 30 and shall be so designed that, depending on the temperature signal, for example, if the temperature inside the housing 27 exceeds a predetermined threshold, and the pressure signal, for example, if the pressure temperature inside the housing 27 exceeds a predetermined threshold, the protective switch 14 can be controlled to open immediately.

In this embodiment of the power supply node 10, the control device 16 is designed to operate the protective switch 14 at the predetermined time interval after the control transformer 11 is operated, so that a delay device 28 as in the first embodiment of the power supply node 10 is not required.

A second embodiment of a process for operating a network node 10 for an electricity network 19 will be described below, wherein the network node 10 is an example of the network node 10 shown in FIG. 2. This second embodiment is similar to the first embodiment, so the differences are explained below in particular.

In this embodiment, step (d) sends a second control signal to the control switch 14 and steps (d) to (c) are executed, for example by means of control device 16.

In step (b), the protective switch 14 shall be opened immediately or immediately or without delay after receipt of the second control signal.

The following shall be added:

10 Network nodes, local power transformer 11 Control transformer 12 Access line 13 Outlet line 14 Protection switch 15 Sensor 16 Controller 17 Surge switch.18 Control device 19 Power supply 20 Circuit 21 Power transformer 22 Subvoltage distribution device 23 Collector rail 24 Access connection 25 Further protection switch 26 Active part of 1127 Housing of 1128 Retardant 29 Temperature sensor 30 Pressure sensor

Claims (14)

1. A network node (10) for a power grid (19), in particular, for a substation or a local network station, comprising

   - a regulating transformer (11) with a primary side and a secondary side;

   - an input line (12), which is connected to the primary side;

   - an output line (13), which is connected to the secondary side;

   - a protective switch (14), which is positioned in the input line (12) or in the output line (13);

   - a sensor (15), which can detect an electrical parameter in the input line (12) and/or in the output line (13) and generate a measurement signal;

   - a control device (16), which is coupled to the regulating transformer (11), to the protective switch (14), and to the sensor (15), and which is formed such that

   • it can control the regulating transformer (11) in dependence on the measurement signal in such a manner that the regulating transformer (11) has a predetermined transmission ratio;

   • it can control the protective switch (14) in dependence on the measurement signal in such a manner that the protective switch (14) opens;

   wherein

   - the opening of the protective switch (14), which is effected by the control, is carried out as soon as the regulating transformer (11) has the predetermined transmission ratio.
2. The network node (10) according to the previous claim wherein

   - the control device (16) is formed such that the control of the protective switch (14) is carried out after the control of the regulating transformer (11).
3. The network node (10) according to the claim preceding the previous claim wherein

   - the control device (16) is formed such that the control of the protective switch (14) is carried out prior to or simultaneously with the control of the regulating transformer (11);

   - the protective switch (14) is coupled to a delay means, which is formed such that it delays the opening of the protective switch (14).
4. The network node (10) according to one of the previous claims, comprising

   - a primary side switchgear (17), comprising

   • the protective switch (14), which is positioned in the input line (12);

   • two input connections;

   • two further protective switches, which each connect one of the input connections to that end of the input line (12) that is not connected to the primary side.
5. The network node (10) according to one of the previous claims, comprising

   - a filter, which is coupled to the input line and/or to the output line and comprises, in particular, a dynamic filter and/or an active filter; and/or

   - a capacitor bank, which is connected to the input line and/or to the output line; and/or

   - an energy storage, which is coupled to the input line and/or preferably to the output line and comprises, in particular, an electrical energy storage and/or a chemical energy storage and/or a thermal energy storage and/or a compressed air reservoir.
6. A regulating transformer (11) for a network node (10) of a power grid (19) wherein the network node (10) is formed, according to one of the previous claims, comprising

   - a primary side and a secondary side;

   - an input line (12), which is connected to the primary side;

   - an output line (13), which is connected to the secondary side;

   - a protective switch (14), which is positioned in the input line (12) or in the output line (13);

   - a sensor (15), which can detect an electrical parameter in the input line (12) and/or in the output line (13) and generate a measurement signal;

   - a regulating device (18) for changing the transmission ratio;

   - a control device (16), which is coupled to the regulating device (18), to the protective switch (14), and to the sensor (15), and which is formed such that

   • it can control the regulating device (18) in dependence on the measurement signal in such a manner that the regulating transformer (11) has a predetermined transmission ratio;

   • it can control the protective switch (14) in dependence on the measurement signal in such a manner that the protective switch (14) opens;

   wherein

   - the protective switch (14) opening, which is effected by the control, is carried out as soon as the regulating transformer (11) has the predetermined transmission ratio.
7. The regulating transformer (11) according to the previous claim, comprising

   - a primary side switchgear (17), comprising

   • the protective switch (14), which is positioned in the input line (12);

   • two input connections;

   • two further protective switches, which each connect one of the input connections to that end of the input line (12) that is not connected to the primary side.
8. The regulating transformer (11) according to one of the previous claims, comprising

   - a housing, in which the active part of the regulating transformer (11) and the regulating device (18) are arranged;

   wherein

   - the protective switch (14) and/or the primary side switchgear (17) are arranged in the housing.
9. The regulating transformer (10) according to one of the previous claims wherein

   - the regulating transformer (11) comprises, on its inside, a temperature sensor, which can generate a temperature signal, and/or a pressure sensor, which can generate a pressure signal;

   - the control device (16) is coupled to the temperature sensor and/or to the pressure sensor and which is formed such that

   • it can control the protective switch (14) in dependence on the temperature signal and/or in dependence on the pressure signal in such a manner that the protective switch (14) opens.
10. A method for operating a network node (10) for a power grid (19) wherein the network node (10), which is formed according to one of the previous claims, comprises

    - a regulating transformer (11) with a primary side and a secondary side;

    - an input line (12), which is connected to the primary side;

    - an output line (13), which is connected to the secondary side;

    - a protective switch (14), which is positioned in the input line (12) or in the output line (13);

    wherein

    - an electrical parameter in the input line (12) or in the output line (13) is monitored;

    - if the parameter meets an error criterion, then

    • the regulating transformer (11) is controlled in a step a)in dependence on the parameter, in such a manner that the regulating transformer (11) has a predetermined transmission ratio, and

    • the protective switch (14) is opened in a step b) in dependence on the parameter;

    - the opening of the protective switch (14) is carried out in step b) as soon as the regulating transformer (11) has the predetermined transmission ratio.
11. The method according to one of the previous claims wherein

    - a first control signal is sent to the regulating transformer (11) in a step c) for the purpose of controlling the regulating transformer (11) in step a); and/or

    - a second or the first control signal is sent to the protective switch (14) in a step d) for the purpose of opening the protective switch (14) in step b).
12. The method according to the previous claim wherein

    - step d) is carried out after step c).
13. The method according to to the claim preceding the previous claim wherein

    - step d) is carried out prior to or simultaneously with step c);

    - the opening of the protective switch (14) is delayed in step b).
14. The method according to one of the previous claims wherein

    - the temperature and/or the pressure is monitored on the inside of the regulating transformer (11);

    - if the temperature meets an error criterion and/or if the pressure meets an error criterion, then the protective switch (14) is opened.