DE102015003802A1 - Method and device for controlling switchable electrical systems - Google Patents

Abstract

In a "smart grid" often intelligent systems that respond individually to the power grid act. A large number of such systems can, because all react to the same system (usually the power grid), have a harmful, synchronized swarming behavior. For example, these systems can get into vibration by stimulating the power grid. In order to prevent a harmful swarming behavior and thus to be able to use the great potential of grid-connected systems for grid control, a device and a method for controlling switchable electrical systems are listed, which does not require higher-level systems, but randomized the individual behavior of the individual grid-connected systems.

Description

The present invention relates to a method and a device for controlling switchable electrical installations. In particular, this means all systems that can shift their operating behavior without significant impairment of the operation time, such as refrigerators or other devices with a (useful) energy storage. In addition, the invention is also applicable to controllable feeder of electrical energy, for. B. combined heat and power plants.

Domestic refrigerators conventionally have a built-in control device that controls the performance of a refrigerant compressor based on the temperature measured in a storage chamber of the refrigerator. The control device of other household appliances, such as dishwashers, washing machines or the like, essentially constitute a user interface through which a user can select and start a function of the machine or a program to be executed by the machine. It has also been proposed to interconnect home appliances with external controllers over a digital network to allow a user to remotely control appliances in his home.

The shortage of fossil fuels, which is likely to increase sharply in the foreseeable future, the effects of global warming, and the environmental and environmental health risks of conventional energy production systems have prompted policy makers to greatly increase the share of renewable generation in the context of the enacted energy transition. But even without politics, the share of renewable energy generation plants in total energy production will inevitably increase. In recent years, for economic reasons are increasingly leading. The growing contribution of renewable, non-renewable sources, such as wind power and photovoltaics, to the public electricity supply poses some serious challenges for those involved in grid regulation. Although the amount of energy from fluctuating generation plants can be predicted to some extent, it can not be controlled in terms of increasing the amount of energy fed in. Any energy shortages must either be addressed in the short term by purchasing energy from other sources or by adjusting consumers' energy consumption behavior. Techniques for this are currently being discussed extensively under the term "smart grid" or intelligent network.

"Smart grid" technologies typically require the existence of a control entity that is able to explicitly or implicitly communicate with both producers and consumers of electrical energy and to influence the power they deliver or absorb to reconcile supply and demand for electrical energy. Explicitly refers here in particular digital information and communication networks. In contrast, the implicit communication designates in particular that network parameters, such. As the frequency and the voltage to be used for information transmission, this is hereinafter referred to as "net-guided". In order for an intelligent network to be successfully implemented, it must first be certain from the electricity supplier that grid-connected systems do not jeopardize grid stability. For this purpose, a control entity is preferably provided which is able to communicate with the consumers in order to influence their power consumption. The grid stability remains safe even when using decentralized controlled systems, if they are properly controlled and regulated. Electrical devices that can function as intelligent consumers in a "smart grid" will be much easier to sell on the market, provided they offer a noticeable advantage. If appropriate control entities are available, Smart Grid enabled devices can gradually spread across the field by replacing old devices. The expected additional costs for the communication interfaces required for new devices may delay the propagation of mains-powered devices.

There is therefore a need for a technique that allows a simple way to modulate the electrical power of an electrical load in accordance with the availability of electrical power in the supply network, without requiring a centralized detection of generated and consumed electrical energy and / or a sophisticated digital Communication between producers and consumers of electrical energy is required.

The integration of such "smart grid" capable smart consumers can support the regulation of the power grid. Due to the individual and non-coordinated behavior of consumers, however, non-linearities can occur at the deficiency level, ie when considering the resulting operating behavior of all grid-connected consumers with regard to the grid. These can cause the electrical network to vibrate, causing adjustment problems. With integration of many network-controlled Devices in the electrical network, the risk of uncontrollable swinging of the electrical network is taken into account. The transmission or distribution system operators will show a much higher willingness to integrate such regulated devices into the network or to be integrated, if appropriate network-based regulations of consumers demonstrably support the network operation.

If a large number of switchable generators (such as CHPs) are network-driven, this swarm of devices can simultaneously react to the network parameters or other information and thus impair network stability. If said swarm responds in the manner described, the net can be made to vibrate. In order to be able to use the potential of mains-powered consumers, a method is required which ensures that the grid-connected devices also exhibit a linear but at least controllable behavior as a swarm and do not additionally burden the electrical network.

In particular, due to the fluctuations of the network parameters, a time-variable shift of the ON and OFF switching thresholds will result from the grid-controlled operation. The movement of the ON and OFF thresholds turns the units ON or OFF, which are in a temperature range that is exceeded by the ON or OFF threshold, and are therefore no longer available for grid control. Influenced by the standard deviation of the described ON and OFF switching threshold movement, an area is formed around the ON and OFF switching thresholds in which no usable devices are left - a so-called dead zone forms (see also FIG Dead zone). Only with a certain shift of the ON or OFF switching threshold can be found again devices that are beneficial to a grid control and can be switched ON or OFF. The crowding-out effects, however, suddenly lead to the emergence of many devices that react abruptly and collectively to the requirements of the grid control system and thus introduce a strong non-linearity into the grid, which can possibly be detrimental. In order to be able to contribute to the grid control, a grid-controlled operation of the devices on the black level should therefore show as linear a behavior as possible.

The above-described object is achieved in such a way by a grid-controlled regulation of the switchable electrical systems, that with every change in the conditions of the network, a predictable number of consumers reacts by a corresponding switching operation from ON to OFF or OFF to ON. Grid-connected systems are available at all times to support grid stability. Between the ON and OFF switching thresholds a desired frequency distribution of the internal system states of the grid-connected systems is to be achieved. In most cases, this will be an even distribution to find the same number of ON-switching or off-switching grid-connected installations at any time and in any load condition. shows this schematically for a swarm net-guided cooling units. On the abscissa is the shift of the ON and OFF switching thresholds, which are shifted depending on the frequency and the voltage. The ordinate represents the resulting change in power consumption of the swarm. The solid line here shows the original operating characteristic, which has jumps. The dotted line corresponds to the adjusted operating characteristic with an underlying uniform distribution.

The present invention is based in a first step on a frequency and / or voltage-dependent limit value for the circuit (see. US 4,317,049 or DE 628 338 ). In this case, the ON and OFF switching value is linearly shifted, and so the energy consumption of the grid-connected system varies with a change in the network parameters, as Equation 1 shows. P _threshold (U, f) = P _soll ± ΔP (U, f) (1)

In a first embodiment, refrigerators are used. The internal system state in this case is the temperature of the various refrigeration devices. shows the internal system state of the swarm forming refrigeration devices as a point cloud that drift with a certain cooling or warming up speed between the temperature limits T _up and T _down back and forth, which is indicated by arrows. The length of the arrow indicates the speed of the movement. In the case of grid-controlled refrigeration appliances, the temperature limits T _up and T _down vary depending on the grid parameters or information from the grid operators or other energy industry players. Considering a large number of line-commutated refrigeration products, this leads to a thinning of the edge regions near T _up and T _down and the formation of a "dead zone (dead zone)," in which only a few are more or no equipment. For the electrical network, this means that changes in the network parameters, which lead to a shift of the ON and OFF switching thresholds in the dead zone, do not change the operating behavior of the refrigeration system swarm and thus initially no support of the grid stability. If the ON and OFF switching thresholds leave the dead zone, there is a sudden increase in the Support of grid stability activated refrigeration appliances. If the jump thus created is large enough, this will result in a disturbance in the electrical network. Between the upper and lower dead zone, a relatively uniform distribution of the devices is likely to occur with only slight change rates of the ON and OFF switching thresholds (cf. ). Strong and rapid movement of the ON and OFF switching thresholds can lead to other distributions as this thins out the area near the ON and OFF switching thresholds when the network parameters are within the setpoint.

In a second step, the present invention deepens the idea that the swarm of controllable grid-connected plants should have a linear operating behavior. Thus, the behavior of the swarm can be better controlled. For this purpose, the plants are operated decentrally and independently of one another by means of corresponding grid-controlled regulations. This reduces the communication effort and the system is robust due to the self-regulating decentralization. Plant-specific parameters should guarantee the properties just mentioned. They modify the operating behavior of the individual plants in such a way that a sufficiently linear behavior is achieved at the higher level of the black coal.

If a large deviation of the ON and OFF switching thresholds occurs, a large number of mains-operated refrigerators starts in the sense of the model to move in the same direction. As the ON and OFF switching thresholds return, a gap results between the previous and current position of the ON and OFF switching thresholds. This effect always occurs when the drift speed of the grid-controlled refrigeration units is slower than the speed of movement of the ON and OFF switching thresholds. Once such a gap has been made, minor changes in the ON and OFF thresholds will not affect the electrical power of the swarm. Such a dead zone can be triggered by the normal vibrations of the ON and OFF switching thresholds. Such a non-linearity is an argument against the integration of grid-connected systems into the electrical network, since the swarming behavior is thus difficult to predict and thus more difficult to control. However, if grid-connected systems are not integrated into the electrical grid, especially on the consumer side, a great potential for supporting grid stability would remain unused.

• – Bewegt sich entweder die EIN- oder AUS-Schaltschwelle entgegen der Bewegungsrichtung des Kältegerätes (Aufwärmen/Abkühlen), wird die durch die Änderung hervorgerufene Verschiebung der EIN- oder AUS-Schaltschwelle als tatsächliche Schaltschwelle des Kältegerätes verwendet.
• – Bewegt sich hingegen entweder die EIN- oder AUS-Schaltschwelle in Richtung der Bewegungsrichtung des Kältegerätes, läuft sie also vom Gerät weg, wird die durch die Änderung hervorgerufene Verschiebung der EIN- oder AUS-Schaltschwelle nicht vollständig übernommen. Stattdessen wird die Differenz der gewünschten EIN- oder AUS-Schaltschwelle zu der aktuellen Temperatur des Gerätes gebildet und diese mit einem vorher per Zufall (z. B. gleichverteilt) festgelegten anlagenspezifischen Parameter c_j, der zwischen 0 (null) und 1 (eins) liegt, multipliziert.

In order to reduce nonlinearities, in this example the ON and OFF switching thresholds of the refrigeration appliances are controlled and regulated as follows (for clarification purposes) ):

• If either the ON or OFF switching threshold moves counter to the direction of movement of the refrigerating appliance (heating / cooling), the shift in the ON or OFF switching threshold caused by the change is used as the actual switching threshold of the refrigerating appliance.
• If, on the other hand, either the ON or OFF switching threshold moves in the direction of the direction of movement of the refrigeration device, ie if it is running away from the device, the shift in the ON or OFF switching threshold caused by the change is not completely taken over. Instead, the difference between the desired ON or OFF switching threshold and the current temperature of the device is formed with a plant-specific parameter c _j previously determined at random (eg, evenly distributed) between 0 (zero) and 1 (one). is, multiplied.

In the event of a jump in the direction of movement, instead of the gap, a distribution of activatable refrigerating appliances is created in accordance with the random distribution of the plant-specific parameter c _j . At the same time, the operating behavior of the swarm approaches a linear operating behavior.

The actual ON and OFF switching thresholds result in this exemplary form according to the following function:

steht für die Bewegung des Kältegerätes j im Temperaturfeld T und

für die Bewegung der EIN- und AUS-Schaltschwelle im Temperaturfeld T durch die Veränderung der Netzparameter, welcher von Kältegerät j bestimmt oder festgelegt wurde. Da die Schwellwertbestimmung nur von der Frage abhängig ist, ob die Richtung der Bewegung gleichgerichtet ist oder nicht, wird der Parameter ν als Skalierungsparameter eingeführt. Entscheidend für die Berechnung der Temperaturschwelle ist, welches Vorzeichen ν hat. Der Parameter c_j ist schließlich der anlagenspezifische Parameter zur Erzeugung der Verteilung in der Lücke. Bei c_j handelt es sich um eine Zufallsvariable, der eine Gleichverteilung zugrunde gelegt ist. Den Kältegeräten wird bei der Produktion ein konstanter Wert zwischen 0 und 1 zugewiesen. Der Zuweisung des Wertes liegt die oben beschriebene Gleichverteilung der Werte zugrunde. Der Index i kennzeichnet, ob es sich um die EIN- oder AUS-Schaltschwelle handelt.T is _{threshold, is, i, j} for the actual temperature _threshold, T _{KS, j j} for the current temperature and T _{threshold, should, i, j} for the calculated from locally measured network parameters and the refrigeration unit j target temperature threshold of the refrigerator j.

stands for the movement of the refrigerator j in the temperature field T and

for the movement of the ON and OFF switching threshold in the temperature field T by the change of the network parameters, which was determined or determined by the refrigeration device j. Since the threshold determination depends only on the question whether the direction of the movement is rectified or not, the parameter ν is introduced as a scaling parameter. Decisive for the calculation of the temperature threshold is, which sign ν has. The parameter c _j is finally the system-specific parameters for generating the distribution in the gap. _Cj is a random variable that is based on an equal distribution. Refrigeration equipment is assigned a constant value between 0 and 1 during production. The assignment of the value is based on the equal distribution of the values described above. The index i indicates whether it is the ON or OFF switching threshold.

T _{threshold, shall, i, j} is determined in this example according to the following equation: T _{threshold, shall, i, j} = T _{i, j} - k _{f, j} · Δf - k _{U, j} · ΔU (3)

Here, k _{f, j} and k _{U, j} control parameters, and .DELTA.f .DELTA.U the deviation of the frequency or voltage actual value from the corresponding desired value and T _{i, j,} the switching threshold as a reference for the non-line-commutated operation.

and show the characteristics with and without the application of the described grid-connected operation for normal operation and after a strong disturbance, as they are exemplary in the simulation of a flock of 800 refrigerators. shows by way of example the resulting swarm behavior with respect to a power reference at different shifts of the ON and OFF switching thresholds (swarm characteristic curve), when the swarm is controlled by an equally distributed system-specific parameter c _j , as described above. The swarm characteristic has no significant break points and even after a strong disturbance of the network, which greatly changes the network parameters, no significant kinks are found. In both cases, no dead zones can be found, which are distinguished by the fact that a shift in the ON and OFF switching thresholds can not cause a power reference change of the swarm. In contrast, shows a chiller swarm that has not been augmented by a plant-specific parameter. Both in normal operation and after a severe power failure, there are strong break points in the swarm characteristics and, much worse, large dead bands in which a slight change in the ON and OFF thresholds will not cause a change in the power draw of the refrigerator swarm. These can sometimes lead to complications in grid regulation. A very similar operating behavior can be achieved with other household appliances, such as washing machines, air conditioners, dishwashers, ovens and hobs (in short: almost all energy-storing household appliances). Again, the recording of electrical energy within certain limits, even taking into account temporal patterns, be temporarily moved. Since this shift in energy intake is systematic and responsive to the shared electrical grid, it can cause a synchronized swarming behavior that can adversely affect the electrical network. To prevent such harmful behavior, as in the above-described refrigeration equipment procedure.

A similar example can also be given for the producer side. If, for example, a combined heat and power plant (CHP) is considered, it can be seen that the operating behavior can also be changed here and the time of the activity can be conditionally postponed. The behavior turns to the consumer side. If the considered network parameters (eg frequency and voltage) are too large an offer of electrical energy in the electrical network, the cogeneration unit (CHP) stops operation or postpones the start of operation. The limits of the shift of the operation are set by the heat storage, as certain temperatures for the useful heat must not be exceeded or fallen below. Within these limits, however, a shift is easily possible.

Analogous to the exemplary embodiment described above with refrigeration appliances, the producers can also be assigned a desired reaction to limit value shifts via a randomly determined plant-specific parameter c. Thus, devices are always in the activatable state and are available to support grid stability. By choosing the distribution of the random variable, the control behavior can also be specifically influenced here.

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

• US 4317049 [0010]
• DE 628338 [0010]

Claims (10)

Method for controlling the power of switchable electrical systems which are connected to the electrical energy supply network and comprise at least one electrical load and / or generator, characterized in that the control responds to locally measured network parameters and the performance of the system of at least one plant-specific parameters is dependent. A method according to claim 1, characterized in that the mains frequency and / or the mains voltage are used as network parameters. Method according to one of claims 1 and 2, characterized in that the response of the plant from OFF to ON is different from the response of the plant from ON to OFF and one or more plant-specific parameters to the reactions of the plant from OFF to ON and / or from ON to OFF and to the other performance of the installation. Method according to one of claims 1 to 3, characterized in that one or more plant-specific parameters are selected according to a random distribution. Method according to one of claims 1 to 4, characterized in that one or more plant-specific parameters control the performance of the electrical systems so that a desired swarm behavior results, in particular a quasi-linear swarm behavior based on the power of the swarm. Device for the performance of switchable electrical installations that are connected to the electrical power supply network and at least one electrical consumer and / or generators include, characterized in that the regulation on locally measured network parameters respond and control the operating behavior of the plant of at least one system-specific parameters is dependent. Device according to claim 1, characterized in that are used as network parameters, the mains frequency and / or the mains voltage. Device according to one of claims 1 and 2, characterized in that the response of the plant from OFF to ON is different from the response of the plant from ON to OFF and one or more plant-specific parameters are related to the reactions of the plant from OFF to ON and / or from ON to OFF and to the other performance of the installation. Device according to one of claims 1 to 3, characterized in that one or more plant-specific parameters are selected according to a random distribution. Device according to one of claims 1 to 4, characterized in that one or more plant-specific parameters control the operating characteristics of the electrical equipment so that a desired resulting swarm behavior, in particular a quasi-linear swarm behavior relative to the performance of the swarm.

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