DE102019122867A1 - METHOD FOR REGULATING ELECTRICAL POWER FLOWS - Google Patents

Abstract

A method for regulating electrical power flows in a multiphase electrical sub-network (10) is described, the sub-network (10) being connected to a higher-level network (20) via a network connection point (11) and wherein a plurality of actuators (12-16 ) are single-phase or multi-phase connected to the sub-network (10) and exchange electrical power (Pi) with the sub-network (10), whereby, by controlling the actuators (12-16), a specification linked to a higher-level control target for a network connection point (11 ) flowing electrical power (PNAP) is met. The method comprises the following steps: - Determination of a target power (PNAP, Soll) to meet the specification, - Determination of a momentary differential power (ΔPNAP) between the desired power (PNAP, soll) and a momentary actual power (PNAP, actual) at the network connection point (11) - Presetting a weighting (Gi) of the differential power (ΔPNAP) per actuator (12-16), - Presetting a value (Wj) per phase (j) of the sub-network (10), - Controlling the actuators (12-16) on the basis of phase-resolved exchange performance specifications (L1, L2, L3), which are determined as a function of the weightings (Gi) and the values (Wj). The sum of all exchange performance specifications (L1, L2, L3) corresponds to the differential power (ΔPNAP)

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to a method for regulating electrical power flows in a multi-phase electrical sub-network that is connected to a higher-level supply network via a connection point.

STATE OF THE ART

A multi-phase electrical sub-network, for example a house network, a network section of a distribution network for supplying an extensive property or a distribution network for supplying a locality, is regularly connected via a node to a higher-level distribution network or transmission network. An active electrical power that flows via this node, for example via a network connection point, depends essentially on the behavior of the electrical devices in the sub-network. Different electrical devices can be connected to the sub-network, in particular energy generation systems, energy consumers and energy stores.

The active power at the grid connection point can be controlled within certain limits by influencing the electrical equipment. Electrical devices whose power consumption or output can be adjusted (hereinafter referred to as "actuators") and which are electrically connected to the sub-network can be used as manipulated variables in a control structure to determine the active power at the network connection point adjust or regulate. The subnetwork can in particular include actuators such as a photovoltaic system (PV system), a battery storage system, an electric car and / or an electric heat generator, that is to say a heat pump and / or a heating element.

The exact capabilities of the individual actuators, i.e. the value range of the currently adjustable active power, may not be known in advance, but can only be recorded indirectly via the effect of a switching action of an actuator on the active power at the grid connection point. If, for example, the active power at the grid connection point is to be reduced because it exceeds a specified target value (so-called peak load shaving), the individual actuators in the sub-network can be switched on or off gradually until the active power is below the target value.

In known methods, for example, a setpoint value for a change in the active power is transferred to a cascade of actuators. The setpoint can include, for example, a reduction in the active power at the grid connection point. This setpoint can first be transferred to a PV inverter or its control unit, which can increase the fed-in power and thus lower the load at the grid connection point. If the available power reserve of the PV inverter (or the PV generator connected to it) is less than the setpoint, i.e. not sufficient to achieve the required change in active power at the grid connection point, the remaining change in power can be transferred to a first e-car as the remaining setpoint be specified, which reduces its charging power within its possibilities; If this is still not enough to achieve the required change in active power at the grid connection point, the updated residual setpoint can be transferred to a second electric car, a heating element and / or a battery, all of which try to do their part to contribute to achieving the desired change in active power. At the end of this cascade, the sum of the changes in power of the actuators should at least correspond to the desired change ΔP in the active power at the grid connection point.

Such a cascaded control can be refined by different weighting of the individual actuators, provided that these actuators can not only be switched on and off, but can also make a specifiable change in their active power. It can make sense to integrate several (similar) actuators into the control system at the same time, but to different degrees, i.e. with different weighting. For example, the memory of a first electric car can be charged with the maximum possible active power, while the memory of a second electric car is not charged at all; alternatively, both e-cars could be charged at “half power”.

Such a weighting of the actuators that can be influenced can be specified, for example, by a higher-level energy management system. User specifications can be taken into account, for example the urgency of charging a storage device in an electric car or supplying a consumer. Any further electrical storage devices can also participate in the regulation, with different boundary conditions being relevant for different storage types, which depend on the intended use of the stored electrical power. For example, a battery can participate in the above-mentioned peak load shaving by emitting electrical power and thus reducing the active electrical power flowing into the sub-network via the network connection point, although it should be noted that energy required for other purposes should remain in the battery, for example for later removal to avoid Active power consumption via the grid connection point, ie in particular to increase self-consumption.

In addition, several battery storage systems can be prioritized against one another, especially if they are assigned to different actuators within the subnetwork independently of one another. For example, if the sub-network has several PV systems that are spatially oriented differently and each coupled with its own battery storage system, it can make sense in the mornings to involve the battery of a PV system facing west more strongly in peak load shaving than the battery of a PV Facility with east orientation, as the former can be charged with higher power in the afternoon due to the relatively stronger solar radiation.

Simultaneous use and weighting of the actuators to achieve a control goal is therefore particularly advantageous if the actuators are required for another purpose that deviates from or even contradicts the control goal, for example the battery of the electric car for driving, a stationary battery for (later) increase in self-consumption, a heat generator and / or a heat storage system to provide heat, etc.

A disadvantage of such methods is that no further actuators are addressed as soon as the setpoint is reached. Therefore, actuators called up first contribute with their full capacity to achieving the setpoint, which in the case of consumers regularly means a complete shutdown, while all other actuators can continue their operation unaffected. This procedure does not result in optimal behavior with regard to the actual, primary purpose of the actuators used.

OBJECT OF THE INVENTION

The invention is based on the object of providing a method for regulating power flows of electrical power in a multiphase electrical sub-network, with which the real power exchanged with the sub-network can be reliably regulated, the actuators connected in the sub-network within the scope of their technical possibilities, taking into account their primary Operational purpose and further user specifications are optimally operated and at the same time optimally contribute to the regulation of the total power exchanged with the subnetwork.

SOLUTION

The object is achieved by a method with the features of claim 1. Preferred embodiments are defined in the dependent claims.

DESCRIPTION OF THE INVENTION

In a method for regulating power flows of electrical power in a polyphase electrical sub-network, the sub-network is connected to a higher-level network via a network connection point. A plurality of actuators is connected to the sub-network in one or more phases and exchanges electrical power with the sub-network. By controlling the actuators, a specification linked to a higher-level control target for electrical power flowing via the network connection point is met. In this case, a target power to meet the specification and a current difference in power between the target power and a current actual power at the network connection point are determined. Furthermore, a momentary weighting of the differential power per actuator and a momentary weighting per phase of the multiphase sub-network are specified. The actuators are then controlled on the basis of phase-resolved exchange performance specifications, the exchange performance specifications being determined as a function of the weightings and the values, and the sum of the exchange performance specifications corresponding to the differential performance.

By means of this method, in particular an actuator that is connected in multiple phases and can be operated asymmetrically can thus be controlled in such a way that power is actually exchanged with the sub-network in a targeted manner. This can be used to avoid overloading individual phases and to minimize unbalanced loads.

A higher-level control goal can be the maximization of self-consumption of electrical energy. In the case of a multi-phase sub-network, the calculation of this self-consumption relates to the sum of the electrical power flowing over the individual phases of the network connection point. The superordinate regulation target can include a target value for an active power at the network connection point, so that the target power correlates with the target value. As an alternative or in addition, the regulation objective can include a limitation of the active power and / or a limitation of the unbalanced load at the grid connection point.

In one embodiment of the method, the actuators can independently set their performance based on the phase-resolved exchange performance specifications or can be allocated a performance preset using the phase-resolved exchange performance specifications from an additional device connected upstream of the respective actuator. This makes the process flexible for a wide variety of actuators applicable, wherein the sub-network can in particular comprise single-phase connected actuators and multi-phase connected actuators.

In embodiments of the method, the actuators can comprise a renewable energy source, in particular a PV system, and an energy store, in particular a battery, and alternatively or additionally an electric car and / or an electric heat generator, in particular a heater. The sub-network itself can be a house network, a network section of a distribution network for supplying an extensive property or a distribution network for supplying a locality or a municipality.

In one embodiment of the method, the actuators have a respective primary benefit which is taken into account when specifying the weighting of the target power per actuator. The primary benefit is the actual operational purpose of the actuator; For example, a heat generator is primarily set up to generate heat and pursues the primary goal of making a requested amount of heat available at the right time, while an electric car is primarily set up for driving and pursues the primary goal of ensuring a sufficient range. The primary benefit can in particular include a minimum reference power of an actuator, for example in that charging an electric car requires a minimum charging power, or in that a compressor of a cooling device requires a minimum start-up power.

In the procedure, the values per phase can represent the relative resilience of the individual phases. Taking into account the power currently exchanged over the individual phases at the grid connection point, it can be identified within the framework of the procedure which power reserves exist in which phases, and this knowledge can be used to redistribute the power over the individual phases.

Figure list

• 1 zeigt ein mehrphasiges Teilnetz mit Anschluss an ein übergeordnetes Netz, und
• 2 zeigt ein erfindungsgemäßes Verfahren zur Regelung von elektrischen Leistungsflüssen in einem mehrphasigen elektrischen Teilnetz.

In the following, the invention is further explained and described with reference to the exemplary embodiments shown in the figures.

• 1 shows a multi-phase subnetwork with connection to a higher-level network, and
• 2 shows a method according to the invention for regulating electrical power flows in a multiphase electrical sub-network.

FIGURE DESCRIPTION

1 shows a multi-phase electrical sub-network 10 that has a network connection point 11 to a higher-level network 20th connected. The network 20th is an electrical AC voltage network and can in particular comprise a distribution network or a transmission network. The subnet 10 can in particular be a house network, a network section of a distribution network for supplying an extensive property or a distribution network for supplying a locality or a municipality.

Within the subnet 10 are different actuators 12-16 arranged over the grid connection point 11 and corresponding power lines electrical power from the grid 20th refer to or in the network 20th feed in. In particular, are in the subnet 10 a burden 12th , for example a commercially available consumer such as a refrigerator or a washing machine, an energy generation system, here in particular a photovoltaic system (PV) 13th , an electrical energy storage device, here in particular a battery 14th , an electrically operated heater 15th , for example a heat pump or a heating rod, as well as an electric car 16 connected.

The subnet 10 is designed in multiple phases, so that the grid connection point 11 and the connections to the actuators 12-16 basically also comprise several phase conductors. The individual actuators 12-16 can be single-phase or multi-phase to the sub-network, depending on requirements 10 be connected.

The subnet 10 includes an energy management system 30th , for example a computer or a controller. The energy management system 30th records the electrical power at the grid connection point 11 by means of suitable measuring devices (not shown) and generates control commands that are sent to the actuators via appropriate communication links (dashed lines) 12-16 be transmitted. The control commands include, in particular, power setpoints generated by the actuators 12-16 each have to be set individually. The actuators 12-16 even be equipped with receivers for the control commands and suitable control devices for setting the respective power setpoints. Alternatively, additional devices (not shown) can be provided that control the actuators 12-16 are connected upstream that receive control commands and one to the actuators 12-16 set allocated or withdrawn electrical power depending on the control commands; Such additional devices can be designed as simple (remotely) switchable sockets for smaller loads or as powerful electrical converters, in particular as (bidirectional and / or multi-phase) inverters, for larger storage units.

Some of the actuators 12-16 , especially the PV system 12th and the battery 14th , can act as an energy source and single-phase or multi-phase electrical power into the sub-network 10 feed in. Due to the multi-phase design of the sub-network 10 and the grid connection point 11 Situations can arise in which the sum of the electrical power in the individual phases at the grid connection point 11 is equal to or close to zero, so there is effectively no real power between subnetwork 10 and network 20th is exchanged. At the same time, however, there can be a significant unbalanced load in that there are significantly different services with opposite power flow directions over the individual phases at the grid connection point 11 flow. For example, the PV system 12th as a single-phase energy source on a first phase of the sub-network 10 be connected and feed in an electrical power, which, however, due to the lack of an energy sink at this first phase within the sub-network 10 is not removed and via the network connection point 11 in the higher-level network 20th drains while an energy sink, for example the load 12th is connected to a second phase of the sub-network and, in the absence of an energy source, electrical power to this second phase via the network connection point 11 from the higher-level network 20th must relate.

On the one hand, such unbalanced loads can occur in conventional subnetworks 10 can be regarded as uncritical if at the grid connection point 11 a balancing electricity meter should be arranged, which only determines the total power over all phases and, if necessary, an operator of the sub-network 10 bills. On the other hand, it does not prove to be very expedient to calculate the sum of the electrical powers in the individual phases at the network connection point when such an unbalanced load is present 11 to be minimized in such a way that the absolute difference between the services on the individual phases and thus the unbalanced load is increased even further. For example, if the power of the PV system fed into a first phase 13th as an energy source higher than that by the load 12th as an energy sink is the power drawn from a second phase, i.e. in total a power from the sub-network 10 in the higher-level network 20th flows, the drawn power of the load could be 12th to be increased on the second phase. This would allow the total power to be minimized, but at the same time the unbalanced load would also be increased, possibly even beyond a normatively permitted level.

Furthermore, some of the actuators 12-16 multi-phase to the sub-network 10 be connected and act as an unbalanced load, ie an asymmetrical electrical power with the individual phases of the sub-network 10 change. Such actuators can act as energy sources, especially the PV system 13th or the battery 14th , or represent energy sinks, especially the load 12th , the heating system 15th or the electric car 16 . In addition, individual actuators can also be operated bidirectionally, ie, if required, they can draw electrical power from the sub-network in one or more phases or feed it into the sub-network.

The energy management system 30th can know both the specific unbalanced load capabilities of the multi-phase connected actuators and the phase actually used by the single-phase connected loads, for example by including or using a method for identifying the phase assignment of an electrical device.

2 shows an embodiment of a method for regulating power flows of electrical power in a polyphase electrical sub-network 10 that has a network connection point 11 with a higher-level network 20th connected is. Via the grid connection point 11 should be an electrical target power P _{NAP, target} from or into the higher-level network 20th flow. The target power P _{NAP, Soll} represents a specification of a higher-level control target, which for example minimizes the energy from the higher-level network 20th related electrical energy includes. In this respect, the specification of the regulation goal can minimize the momentary over the network connection point 11 related electrical power P _NAP , so that the higher-level control target in this example can be represented by a target power P _{NAP, target} equal to zero.

In one acquisition section 31 of the method, the setpoint power P _{NAP, setpoint is combined} with an actual electrical power P _{NAP, lst} at the network connection point 11 compared and a difference in power .DELTA.P _{NAP formed} between target and actual power. This desired differential power .DELTA.P _NAP is sent to a control section 32 passed the procedure. The regulatory section 32 generated by means of an energy management system 30th phase-resolved exchange power specification for the actuators 12-16 who have favourited the actuators 12-16 in an action section 33 of the procedure and, if possible, implement it.

In order to set the target power P _{NAP, Soll} , the exchange _{powers P i of} several of the actuators are thus used 12-16 in the subnet 10 based on the regulation section 32 influenced as a function of a higher-level control objective, in particular by adding individual exchange performance specifications ΔP _i to these actuators 12-16 or their controls or ballasts are transmitted. An exchange power specification ΔP _i can be an absolute value for the exchange power P _{i of} one of the actuators 12-16 or also a change in the exchange power P _{i of} one of the actuators 12-16 pretend.

To determine a suitable exchange performance specifications .DELTA.P _i are the actuators 12-16 in each case individual weightings G _i with values between 0 and 1 assigned. The weightings G _{i can} be normalized in such a way that their sum is equal to one. The weightings can concretely from the energy management system 30th calculated and by means of a distributor 34 can be applied to the differential power ΔP _NAP. This results in weighted performance targets 12a-16a for the actuators 12-16 calculated by dividing the power difference ΔP _NAP required for setting the setpoint power P _{NAP, setpoint} with that of the respective actuators 12-16 assigned weighting G _{i is} multiplied.

On the performance targets 12a-16a become phase factors 35 applied. For this purpose, the energy management system 30th Weights W _j for the individual phases of the sub-network 10 given. The weights W _j include values between 0 and 1, it being possible for the sum of the weights W _{j to be} equal to one. Specifically, for example, a phase j to which predominantly non-controllable electrical loads are connected can be assigned a lower weight W _j than the other phases.

The performance targets 12a-16a are with a on the respective actuator 12-16 applicable set of phase factors 35 multiplied. This results in phase-resolved exchange performance specifications for the actuators 12-16 , in the 2 are named redundantly with L1, L2, L3 for the sake of clarity. With these phase-resolved exchange performance specifications L1, L2, L3, the actuators 12-16 in the action section 33 controlled.

When determining the exchange performance specifications ΔP _i for the actuators 12-16 it is thus taken into account which phase j has which value W _j . For this purpose, a differential power ΔP _{NAP is used} at the network connection point 11 , which should be minimized by the exchange _{performance specifications ΔP i,} for example, on the actuators 12-16 divided by the differential power .DELTA.P _NAP multiplied by the weightings G _i and distributed to the individual phases j on the basis of the weights W _j.

For an actuator that is connected in multiple phases and can be operated asymmetrically, for example for the battery 14th or the electric car 16 , the exchange performance specification consists of three values L1, L2, L3 by adding the corresponding performance specification 14a or 16a is multiplied by the weights W _j; the sum of the values L1, L2, L3 for each of the actuators 14th or. 16 essentially the respective performance specification 14a or. 16a correspond. The resulting phase-resolved exchange performance specifications are sent to the actuators 14th , 16 transmitted so that they exchange electrical power with the subnetwork asymmetrically.

Specifically, for example, a phase j with a low value W _j , from which a relatively high power is already drawn, can be less due to the asymmetrically operated electric car 16 are burdened as a phase j with high value W _j , which is still relatively little burdened. This avoids an overload on phase j with low significance W _j and at the same time minimizes an unbalanced load at the network connection point NAP. In this example, the value represents the relative load capacity of the individual phases, ie their possible contribution to an increase in active power. Basically there are many more definitions or derivations for the weights W _j and the application of the phase factors 35 conceivable, with the specific values also being able to depend in particular on the overriding control objective.

For the single-phase connected actuators, for example the load 12th or the PV system 13th , the phase-resolved exchange performance specifications consist of only one value. This value can also result from the multiplication of the corresponding performance specification 12a or. 13a with the value W _{j of} the respective phase j to which the load 12th or the PV system 13th connected. The exchange power specification is all the smaller, the lower the value W _{j of} that phase j to which the actuator is connected. As a result, a phase j with a low value W _j , from which, for example, a lot of electrical power is already drawn by the uncontrollable loads, is only _{used to a small extent to compensate for the differential power ΔP NAP} . Conversely, those single-phase actuators can preferably _{contribute to the differential power ΔP NAP} which are connected to phases j with the highest valency W _j ; In the above example, these are precisely the phases j from which the least amount of electrical power is drawn by the uncontrollable loads.

The actuators are now instructed to implement the phase-resolved exchange performance specifications L1, L2, L3 by in particular the exchange performance P _{i of} the actuators 12-16 is changed accordingly. Subsequently, based on the measured values at the grid connection point 11 evaluated to what extent the actual power P _{NAP, actual corresponds} to the target power P _{NAP, target} . If the differential power .DELTA.P _NAP still has a value not equal to zero, the described method can be iteratively run through again in order to regulate the remaining difference between the actual power and the target power by means of further optimized exchange power specifications.

In one embodiment it can be determined to what extent the actuators 12-16 have actually implemented the exchange service specification instructed to them. This determination can be made by measuring the exchange powers P _{i of} the actuators 12-16 take place, this measurement by the actuators 12-16 made by itself and communicatively with a control unit, for example the energy management system 30th can be provided. Especially if one or more of the actuators 12-16 does not provide the respectively required (phase-resolved) exchange performance specification, the weightings G _{i of} these actuators, which do not or could not provide the required exchange performance P _{i, can} be set to 0 in one iteration of the method. The other weights are re-normalized and the remaining differential power ΔP _NAP is distributed to the remaining actuators. This iteration is continued until the actual power P _{NAP, actual corresponds to} the setpoint power P _{NAP, setpoint} at the connection point and thus the specification that is linked to the higher-level control objective is met.

In further embodiments, the weighting can take into account already known boundary conditions of individual actuators, such as, for example, predetermined minimum powers of certain actuators. This ensures that the corresponding actuators are not placed in an invalid operating state, for example in that an actuator receives a power specification that is lower than the respective predetermined minimum power.

In other embodiments, instead of the (balanced) active power at the network connection point, other variables can also be regulated, such as the active power at critical points in the sub-network or phase-resolved active and / or apparent power.

List of reference symbols

10

Subnet

11

Grid connection point

12-16

Actuators

12a-16a

Performance specification

20th

network

30th

Energy management system

31

Acquisition section

32

Regulatory section

33

Action section

34

Distributor

35

Phase factors

Claims (11)

Method for regulating electrical power flows in a multi-phase electrical sub-network (10), the sub-network (10) being connected to a higher-level network (20) via a network connection point (11) and wherein a plurality of actuators (12-16) are single-phase or multi-phase are connected to the sub-network (10) and _{exchange electrical power (P i} ) with the sub-network (10), whereby, by controlling the actuators (12-16), a specification linked to a higher-level control target for an electrical flow via the network connection point (11) Power (P _NAP ) is met, the method comprising the following steps: Determining a target power (P _{NAP, soll} ) to meet the specification, - Determining a momentary difference in power (ΔP _NAP ) between the target power (P _{NAP, soll} ) and a current actual power (P _NAP , actual) at the grid connection point (11), - specification of a weighting (G _i ) of the differential power (ΔP _NAP ) per actuator (12-16), - specification of a value (W _j ) per phase (j) of the sub-network (10), - controlling the actuators (12-16) on the basis of phase-resolved exchange performance specifications (L1, L2, L3), which are dependent on the weightings (G _i ) and the values (W _j ), whereby the sum of all exchange power specifications (L1, L2, L3) corresponds to _{the differential power (ΔP NAP).} Procedure according to Claim 1 , wherein the overriding regulation target comprises a target value for an active power at the network connection point (11), so that the target power (P _NAP, target) correlates with the target value. Procedure according to Claim 1 or 2 , wherein the regulation goal comprises a limitation of the active power at the grid connection point (11). Method according to one of the preceding claims, wherein the regulation goal alternatively or additionally comprises a limitation of the unbalanced load at the network connection point (11). Method according to one of the preceding claims, wherein the actuators (12-16) independently set their performance based on the phase-resolved exchange performance specifications (L1, L2, L3) or a performance specified using the phase-resolved exchange performance specifications (L1, L2, L3) of one of the respective actuators (12-16) upstream additional device. Method according to one of the preceding claims, wherein the sub-network comprises single-phase connected actuators (12, 13, 15) and multi-phase connected actuators (14, 16). Method according to one of the preceding claims, wherein the actuators (12-16) comprise a renewable energy source, in particular a PV system (13), and an energy store, in particular a battery (14). Method according to one of the preceding claims, wherein the actuators (12-16) comprise an electric car (16) and / or an electric heat generator, in particular a heater (15). Method according to one of the preceding claims, wherein the sub-network (10) is a house network, a network section of a distribution network for supplying an extensive property or a distribution network for supplying a locality or a municipality. Method according to one of the preceding claims, wherein the actuators (12-16) have a respective primary _{benefit which is taken into account when specifying the weighting (G i} ) of the target power (P _{NAP, soll} ) per actuator (12-16), the primary benefit in particular includes a minimum reference power of an actuator (12-16). Method according to one of the preceding claims, wherein the values (W _j ) represent the relative resilience of the individual phases (j).

Images