DE102014208396A1 - Electric consumer and method of operating an electrical consumer - Google Patents

Abstract

Electric consumer (100), comprising: - an interface device (10) by means of which the load (100) can be connected to an AC mains (W), - a power converter device (20) which can be controlled by means of a first control device (30), and - A second control device (40) to which an electrical characteristic (K) of the AC network (W) can be supplied, wherein by means of the power converter means (20) in dependence on the electrical characteristic (K) of the AC network (W) an electrical voltage of the AC mains ( W), wherein a control variable (R) for the first control device (30) can be provided by the second control device (40).

Description

The invention relates to an electrical load and a method for operating an electrical load.

State of the art

Electric heat pumps play an increasingly important role in the heating and air conditioning of buildings (eg for cooling, heating, hot water treatment, etc.). This electrical energy is used to provide heat or dissipate. Using electrical power can reduce the electrical voltage in the power grid to which the electric heat pump is connected. For permissible electrical voltage changes in the public power grid, limits defined in standards, such as the EN 50160 , As a result, it is possible that power grids may be overloaded, possibly preventing the connection of additional heat pumps.

• – Für Erzeuger und Verbraucher kann eine Senkung bzw. eine Begrenzung der eingespeisten Wirkleistung vorgesehen sein. Dies ist zum Beispiel bekannt aus DE 10 2012 016 846 A1 .
• – Für Erzeuger (z.B. Fotovoltaikanlagen, Kraft-Wärme-Kopplungsanlagen, usw.) ist ein Blindleistungsbezug während der Einspeisung, das heißt eine Einstellung des Phasenwinkels φ zwischen elektrischer Spannung und elektrischem Strom vorgesehen. Dies ist beispielsweise aus den Normen VDE AR N 4105 und EN 50438 bekannt.

It is known from the prior art that the electrical mains voltage is kept within a permissible range by the following possibilities:

• - For producers and consumers, a reduction or limitation of the injected active power can be provided. This is known for example DE 10 2012 016 846 A1 ,
• - For producers (eg photovoltaic systems, combined heat and power plants, etc.) is a reactive power reference during the feed, that is, an adjustment of the phase angle φ between electrical voltage and electric current provided. This is for example from the Standards VDE AR N 4105 and EN 50438 known.

It is also known that although a regulation of the reactive power positively influence the electrical voltage, it can increase the load on the electrical supply network, in particular of a transformer used therein.

Disclosure of the invention

It is therefore an object of the present invention to provide an improved use of an electrical load in an electrical power grid.

• – eine Schnittstelleneinrichtung, mittels der der Verbraucher an ein Wechselstromnetz anschließbar ist,
• – eine Stromrichtereinrichtung, die mittels einer ersten Regelungseinrichtung ansteuerbar ist, und
• – eine zweite Regelungseinrichtung, der eine elektrische Kenngröße des Wechselstromnetzes zuführbar ist, wobei mittels der Stromrichtereinrichtung in Abhängigkeit von der elektrischen Kenngröße des Wechselstromnetzes eine elektrische Spannung des Wechselstromnetzes regelbar ist, wobei von der zweiten Regelungseinrichtung eine Regelgröße für die erste Regelungseinrichtung bereitstellbar ist.

The object is achieved according to a first aspect with an electrical consumer, comprising:

• An interface device by means of which the consumer can be connected to an AC mains,
• - A power converter device which is controllable by means of a first control device, and
• - A second control device to which an electrical characteristic of the AC power supply can be fed, wherein by means of the power converter device in dependence on the electrical characteristic of the AC power supply, an electrical voltage of the AC power supply is controllable, wherein a control variable for the first control device is provided by the second control device.

• – Erfassen einer elektrischen Kenngröße des Wechselstromnetzes;
• – Zuführen der Kenngröße an eine zweite Regelungseinrichtung des Verbrauchers; und
• – Regeln einer elektrischen Spannung des Wechselstromnetzes in Abhängigkeit von der Kenngröße.

According to a second aspect, the object is achieved with a method for operating an electrical consumer, which is connected to an electrical alternating current network, comprising the steps:

• - detecting an electrical characteristic of the AC network;
• - supplying the parameter to a second control device of the consumer; and
• - Rules of an electrical voltage of the AC network as a function of the characteristic.

In this way, the electrical load is enabled to simultaneously draw active power and simultaneously supply reactive power to or from the AC mains, thereby controlling an electrical voltage level. By way of example, this can be used to maintain or not exceed a desired value of the electrical voltage. Advantageously, in this way electrical voltages can be limited or at least extremes of the electrical voltages can be reduced without impairing the functionality of the consumer.

Advantageous developments of the electrical load and the method are the subject of dependent claims.

An advantageous development of the consumer according to the invention is characterized in that the characteristic used is an electrical voltage of the AC mains or a power absorbed by the AC mains. In this way, different characteristics of the AC network can be used for the consumer, thereby a variety of operating modes for the consumer is supported.

A further embodiment of the consumer is characterized in that the controlled variable is a reactive power or a phase angle. This provides different options for regulating the voltage by the consumer provided. For example, can be specified by a network operator to the consumer a network service to be provided in the form of reactive power, which can meet the consumer with the control variable reactive power substantially.

A further advantageous development of the consumer is characterized in that the second control device is one of the following group: P controller, PI controller, PID controller. In this way, different control strategies for the AC network can advantageously be implemented with different controller types.

A further embodiment of the consumer is characterized in that the second control device provides control signals for semiconductor switches of the power converter device or for passive components of the power converter device. In this way, different options for implementing the selected control strategy are advantageously supported for the consumer.

A further embodiment of the consumer provides that the electrical voltage of the AC mains is detected internally or externally by the power converter device. In this way, different detection points of the electrical voltage can be specified to the consumer, whereby a higher-level control strategy with multiple producers and consumers can be implemented.

The invention will be described below with further features and advantages with reference to several figures in detail. In this case, all features, regardless of their representation in the description and in the drawings, as well as regardless of their dependency in the claims, the subject of the invention. The figures are intended in particular to clarify the principles essential to the invention.

In the figures shows:

1 a schematic diagram for explaining a known method in which by a generator reactive power is fed into the power grid;

2 a diagram for explaining the phase angle in the Verbraucherzählpfeilsystem;

3 an embodiment of an electrical consumer;

4 a characteristic of a regulatory strategy that is feasible with the consumer;

5 a representation of thresholds for the implementation of the regulatory strategy by the consumer;

6 a characteristic of another regulatory strategy that is feasible with the consumer;

7 a characteristic of another regulatory strategy that is feasible with the consumer;

8th a characteristic of another regulatory strategy that can be realized with the consumer; and

9 a basic sequence of an embodiment of the method.

Embodiments of the invention

1 shows in principle that electrical generators feed electrical reactive power Q in a known manner in an electrical AC mains W. In the left-hand illustration, a diagram with four quadrants can be seen, wherein on the x-axis a ratio of an active power P to a nominal active power P _n and on the y-axis a ratio of a reactive power Q to the nominal active power P _{n is} shown. The negative sign on the x-axis indicates an injection of active power P into the alternating current network W. Hatching marks an area that needs to be covered or provided by the producer in terms of performance. This means that the producer must be able to either feed or purchase a certain amount of reactive power while providing some active power.

In the right representation of 1 a characteristic of a control strategy is shown, which provides that the generator below a defined active power value P ₁ and above a defined active power value P _2, a defined reactive power value is fed into the AC grid. In generators, this principle is often used to lower the voltage, otherwise the voltage would rise above a maximum limit.

2 shows a definition of a consumer counting arrow system, which is always used below. Recognizable is a coordinate system with the active power P on the x-axis and the inductive reactive power Q on the positive y-axis and the apparent power S as an amount of power, as a complex sum of active power P and reactive power Q under a defined phase angle φ to the active power P is arranged.

3 shows a first embodiment of an electrical consumer according to the invention 100 , The consumer 100 has an electrical power conversion device 20 on, which may be formed in the case of an electric motor or a brushless DC motor, for example, as a frequency converter or in the case of a DC motor as a rectifier. The consumer 100 may be an AC consumer or a DC consumer, he must in any case an interface device 10 have to realize an electrical connection to an electrically powered AC mains W. In the case of a rectifier / inverter this assumes the function of the interface device 10 ,

The consumer 100 further comprises a first control device 30 that is used to power the converter 20 with control signals for semiconductor switch (not shown) of the power converter 20 head for. The first control device 30 can do this internally or externally by the consumer 100 be arranged. An electrical parameter K of the AC network W is measured or detected and a second control device 40 of the consumer 100 supplied, whereupon the second control device 40 to the first control device 30 a controlled variable R (eg one from the power converter 20 to be set phase angle φ or one of the converter 20 to be set value of a reactive power Q).

As a result, this means that depending on the state of the AC mains W from the power converter 20 in the AC mains W, a reactive power Q is either fed or from the AC mains W, a reactive power Q is obtained. This means a regulating influence on the electrical voltage V of the AC mains W, which allows the electrical voltage V of the AC mains W to remain within predefined limits. It can thereby be achieved that a defined level of the electrical voltage V is not exceeded or undershot. Advantageously, this means that a negative influence of powerful electrical consumers 100 is limited to an electrical voltage level, the power grid W, creating a larger number of electrical consumers 100 can be connected to the power grid W.

The consumer 100 For example, it is equipped with a voltage measurement which can be arranged either at a house connection or at the device itself or at an electricity meter (eg by means of a smart meter) or within a domestic installation. From outside the house, a signal can be transmitted via a communication interface (eg from the network operator, aggregator). In the event that the power supply is outside the consumer 100 is, the measured value via a communication line or via a wireless communication interface (not shown) to the consumer 100 be transmitted. Alternatively, a reactive power demand from the sensor to the consumer may also be directly available 100 be transmitted.

4 shows a characteristic of a first regulatory strategy with the consumer 100 is feasible. It provides that electrical reactive power Q from the consumer 100 is then provided when of the electrical characteristic K of the AC mains W, to which the consumer 100 is deviated. As controlled variable R, the phase angle φ is used, which also defines a phase shift between current and voltage of the alternating current network W. It is set such that reactive power Q is either sourced or fed in, so that the voltage value V moves back to the so-called "deadband range" T of the electrical voltage V.

For this purpose, the electrical mains voltage V is measured or detected, the phase angle φ being set in such a way that the reactive power Q is generated in addition to the active power reference when the voltage Vset_min falls below a specified voltage limit. A reactive power flow against the active power flow leads to a voltage increase at the connection point of the electrical load 100 at the AC mains W. The adjustment of the phase angle φ is preferably done by a control of power electronic switches of the power converter device 20 of the consumer 100 , Alternatively, it is also conceivable that passive components, for example in the form of coils and capacitors (eg stepwise) are switched. In this way is to implement the regulatory strategy in the consumer 100 advantageous not necessarily a power electronics required.

• – maximaler bzw. minimaler Phasenwinkel φ
• – Steigung der Flanken der Kennlinie
• – Schwellwerte Vset_min und Vset_max

4 thus shows a reactive power control, expressed in cos (φ) as a function of the electrical voltage V. The reactive power control is based on a voltage-phase angle φ characteristic, which is characterized by the following characteristics:

• - maximum or minimum phase angle φ
• - Slope of the flanks of the characteristic
• - Thresholds Vset_min and Vset_max

• – Identisch sein
• – Voneinander unabhängig sein
• – Anhand einer Netzspannungsmessung im ausgeschalteten Zustand des Verbrauchers 100 definiert werden (z.B. täglich). Der Sollwert wird auf diese Spannung oder leicht darunter gesetzt
• – Anhand einer Mittelwertbildung über eine Spannungsmessung (z.B. im ausgeschalteten) Zustand des Verbrauchers 100 definiert werden
• – In Abhängigkeit der Position des Verbrauchers 100 am Strang des Wechselstromnetzes W eingestellt werden

The two voltage thresholds Vset_min and Vset_max can have one or more of the following properties:

• - Be identical
• - be independent of each other
• - Based on a mains voltage measurement in the off state of the consumer 100 be defined (eg daily). The setpoint is set to this voltage or slightly below it
• - By averaging over a voltage measurement (eg in the off state) of the consumer 100 To be defined
• - Depending on the position of the consumer 100 be set on the strand of AC mains W.

In this case, it is particularly favorable to set the values of the voltage threshold values Vset_min and Vset_max from a grid feed point, e.g. a medium-voltage / low-voltage transformer, to set the end of the line ascending / descending. In this case, the fact can be used in particular that the voltage drop or increase can be calculated by the reference or the supply of a specific active power P or reactive power Q based on the loop impedance.

Preferably, a definition of the values Vset_min and Vset_max is performed once, for example in an initialization phase of the electrical load 100 , This may in particular be based on one at the connection point of the consumer 100 carried out measurement of the loop impedance of the AC mains W.

5 shows exemplary characteristics of the characteristic values Vset_min and Vset_max as a function of a position of the consumer 100 related to a connection point. In each case, three curves of Vset_max and Vset_min are shown, wherein it can be seen that a profile of the mentioned characteristic values is at a distance d of the electrical consumer 100 depends on the connection point.

6 shows qualitatively a characteristic of another possible regulation strategy for the consumer 100 , Shown is a course of a reactive power control as a function of an electrical voltage V. Visible again are the two characteristic values Vset_max and Vset_min, which limit the deadband area T, within which of the consumer 100 No reactive power control is performed. In the case of a deviation of the voltage V from the deadband region T, it is attempted by means of the reactive power regulation to lead the electrical voltage V in turn into the deadband region or at least approach the deadband region T.

• – Maximale bzw. minimale Blindleistung Q
• – Steigung der Flanken der Kennlinie
• – Kennwerte vset_min und Vset_max

The characteristic of 6 is characterized by the following properties:

• - Maximum or minimum reactive power Q
• - Slope of the flanks of the characteristic
• - Characteristics vset_min and Vset_max

• – maximaler Phasenwinkel φ
• – Steigung der Flanke der Kennlinie
• – Totbandbereich T der Wirkleistung P

Also 7 shows in principle a further characteristic of a control strategy for the consumer 100 , in this case as a reactive power control, expressed in cos φ as a function of the active power P of the consumer 100 is trained. Advantageously, such a refinement of the control strategy is particularly low in vibration. The reactive power control in this case is based on a power phase angle characteristic, which is characterized by the following characteristics:

• - maximum phase angle φ
• - slope of the slope of the characteristic
• Deadband area T of active power P

• – Maximale Blindleistung Q
• – Steigung der Flanke der Kennlinie
• – Totbandbereich T der Wirkleistung P

8th shows in principle a characteristic of another possible control strategy for the consumer 100 expressed in terms of reactive power Q as a function of that of the electrical consumer 100 In this case, power control is based on a power / reactive power characteristic which can be represented by the following characteristics:

• - Maximum reactive power Q
• - slope of the slope of the characteristic
• Deadband area T of active power P

The consumer 100 can be designed in particular as an electric drive motor of a heat pump. In addition to heat pumps, however, other electrical consumers 100 , Such as refrigerators, washing machines, dishwashers, etc. are formed according to the invention.

The previously described setting of the reactive power Q without influence on the active power consumption of the consumer 100 Although a slightly more powerful dimensioning of the power converter device 20 require. Will the power converter device 20 designed for the active power P, the adjustment of the reactive power Q can also be done at a constant apparent power S, the reactive power supply is accompanied in this case with an active power reduction.

Unless a communication of the consumer 100 with a transformer (medium voltage / low voltage transformer) is possible, the transformer can the consumer 100 provide information about its current load. As long as the transformer is not overloaded, it can be the consumer 100 Enable the reactive power control, if it comes close to the overload, the reactive power control is disabled and it reduces the active power of the consumer.

Advantageously, the invention can also be used in the medium-voltage network, wherein instead of the medium-voltage / low-voltage transformer then the next higher voltage level (high voltage / medium voltage transformer) must be considered.

The control strategies described above can thus with the second control device 40 be implemented, wherein the second control device 40 is implemented as a P controller, PI controller or PID controller. The simplest control strategy is represented by the P controller, in which case only a characteristic function without threshold values is implemented.

9 shows a basic sequence of an embodiment of the method. In a first step 201 a detection of an electrical characteristic K of the AC network W is performed.

In a second step 202 is the characteristic K to a second control device 40 of the consumer 100 fed.

Finally, in a third step 203 a regulation of an electrical voltage V of the AC network W as a function of the characteristic K performed.

In summary, the present invention proposes an electrical consumer and a method for operating such a consumer, with which it is possible for the consumer without influencing an active power reference to keep a voltage level of the supplying AC network within normative limits. In particular, it is possible to restrict a negative influence of many powerful consumers on a voltage level of the supply network.

In this way, it is possible to respond to an increased electrical voltage level in the alternating current network W, which results, for example, from an increased energy feed of photovoltaic systems into the alternating current network W, without restricting the operation of the consumer. As a result of the reduced influence on the voltage level of the alternating current network W, a risk of damage / failure of other consumers due to a too low electrical voltage V can thus advantageously be reduced.

Advantageously, the invention as a software for the consumer 100 be implemented, for example, in an electronic computing device of the control devices, whereby an easy adaptability is supported.

Although the invention has been described above by means of specific embodiments, it is by no means limited thereto. The person skilled in the art will thus be able to modify or combine the features described without departing from the essence of the invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012016846 A1 [0003]

Cited non-patent literature

• EN 50160 [0002]
• Standards VDE AR N 4105 [0003]
• EN 50438 [0003]

Claims (14)

Electric consumer ( 100 ), comprising: - an interface device ( 10 ), by which the consumer ( 100 ) is connectable to an AC mains (W), - a converter device ( 20 ), which by means of a first control device ( 30 ) is controllable, and - a second control device ( 40 ), to which an electrical parameter (K) of the AC network (W) can be supplied, wherein by means of the power converter device ( 20 ) in dependence on the electrical parameter (K) of the AC network (W), an electrical voltage of the AC network (W) is controllable, wherein of the second control device ( 40 ) a control variable (R) for the first control device ( 30 ) is available. Consumer ( 100 ) according to claim 1, characterized in that as an indicator (K) is an electrical voltage of the AC mains (W) or one of the AC mains (W) recorded active power (P) is used. Consumer ( 100 ) according to claim 2, characterized in that the controlled variable (R) is a reactive power (Q) or a phase angle (φ). Consumer ( 100 ) according to one of claims 1 to 3, characterized in that the second control device ( 40 ) is one of the following group: P controller, PI controller, PID controller. Consumer ( 100 ) according to one of the preceding claims, characterized in that the second control device ( 40 ) Control signals for semiconductor switches of the power converter device ( 20 ) or for passive components of the power converter device ( 20 ). Consumer ( 100 ) according to one of the preceding claims, characterized in that the electrical voltage of the AC network (W) internally or externally from the power converter device ( 20 ) is detected. Consumer ( 100 ), characterized in that the consumer ( 100 ) is an electric heat pump. Method for operating an electrical consumer ( 100 ) connected to an AC electrical network (W), comprising the steps of: - detecting an electrical characteristic (K) of the AC network (W); - supplying the parameter (K) to a second control device ( 40 ) of the consumer ( 100 ); and - regulating an electrical voltage of the AC network (W) as a function of the parameter (K). Method according to claim 8, wherein the parameter (K) determines the electrical voltage of the alternating current network (W) or one of the consumer ( 100 ) from the AC mains (W) recorded electrical active power (P) of the consumer ( 100 ). A method according to claim 8 or 9, wherein a region (T) of the characteristic (K) is defined in which the electrical voltage of the AC network (W) is not regulated. Method according to claim 10, wherein the range (T) is limited by limit values (Vset_min, Vset_max) which depend on a geometric position of the consumer ( 100 ) are set on a distribution line of the AC network (W). Method according to one of claims 8 to 11, wherein the electrical voltage within the consumer ( 100 ) or externally to the consumer ( 100 ) is transmitted. Use of an electrical consumer ( 100 ), whereby the consumer ( 100 ) by means of an interface device ( 10 ) is connectable to an alternating current network (W), wherein in dependence on an electrical parameter (K) of the alternating current network (W), which to the consumer ( 100 ), an electrical voltage (V) of the AC network (W) is controllable. Computer program product with program code means for carrying out the method according to one of Claims 8 to 12, when it is stored on an electronic control device ( 30 ) or stored on a computer-readable medium.

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