AT514766A1 - Method for stabilizing an energy distribution network - Google Patents

Abstract

Method for stabilizing an energy distribution network (3) involving an energy management system (1) of at least one building (2), wherein - in the energy distribution network (3) at a location in the area from the network connection point of the building to the energy distribution cabinet of the building, the voltage and / or at a Current measured from the network connection point of the building in the area up to the nearest transformer of the energy distribution network (3), - the voltage measured values compared with a predetermined, the grid stability ensuring voltage-effective and reactive power characteristic and / or the current measured values with a predetermined , the current stability and reactive power characteristic curve guaranteeing grid stability are compared, - the difference between the measured values and the characteristic is forwarded to the energy management system, and - if it is exceeded by the reactive power characteristic or the active power characteristic Area the energy management system (1) calculates which components of the building must change their power to return to the range within the reactive power characteristic, - and the power change is performed by the component (7).

Description

description

Method for stabilizing an energy distribution networkTechnical field

The invention relates to a method for stabilizing an energy distribution network including a

Energy management system of at least one building, and a corresponding device.

Energy management includes the planning and operation of energy production and consumption units. The aim is to conserve resources as well as climate protection and cost reductions, while ensuring the energy needs of users.

State of the art

The traditional grid operation in the electricity supply is facing great challenges due to the increasing penetration of decentralized, renewable energy generation systems (DEA). Added to this is the development of electromobility and thus an increase in the substitution of other forms of energy transmission by electricity. The so-called "Smart Grid" is seen as a solution to these problems. The smart grid or network comprises the communicative networking and control of power generators, storage, electrical consumers and network resources in power transmission and distribution networks of the electricity supply.

Network stability in energy transmission and distribution networks can be primarily compromised in two areas: The predominant problem in rural networks is voltage maintenance, which is also known as "U-problem". referred to as. In urban networks, which tend to have short line lengths due to the load density, less the maintenance of voltage than the problem of resource utilization is more prevalent. This is also called the "I problem". designated. Distributed feeders initially reduce the high utilization of lines and transformers. In the rarest cases, however, the power limits in the feedback are violated.

And it can also be e.g. In suburban areas, network sections within a network area are more rural and urban in nature. In order to comply with the voltage limits prescribed by standards (such as EN50160) or to overload the equipment at the last instance, either network expansion or an active network management system must be used. The latter specifically targets producers, flexible consumers or even storage in the network in order to maintain network operation in accordance with the standards.

In the future, so-called "Smart Buildings", also referred to as intelligent homes or smart buildings, will also include components such as fluctuating generators (e.g., photovoltaic systems, small wind turbines), flexible consumers and storage for electrical energy, or the charging infrastructure for electric vehicles. The building will be "smart" or intelligently through the use of a modern building automation system. Building automation includes the entirety of monitoring, control, and optimization devices in buildings. The aim is to carry out functional processes independent of the component (automatically) and according to preset settings (parameters). All sensors, actuators, controls, consumers and other technical units in the building are networked together. Processes can be summarized in scenarios. Characteristic feature is the continuous networking by means of a bus system.

The building automation systems of the Smart Buildings, or the energy management systems as part of the

Building automation systems, therefore, must optimize the internal needs of electrical and thermal energy for the individual components of the building, create local (building-related) forecasts and take account of flexible tariff specifications, which have market- or network-specific proportions.

However, this means that the smart grid can not have access to the individual components of a smart building, because otherwise the building-internal optimization, such as the so-called day-ahead optimization, would no longer be possible.

For electricity generating plants > 100kW is therefore approximately in Germany due to the so-called

Medium Voltage Directive (Directive for connection and parallel operation of generation plants on the medium-voltage network) provided that the electricity generating plants of itself for structural and dynamic network stabilization must contribute. Similar requirements could therefore be met in the future by smaller electricity generation plants, such as those in Smart Buildings.

Presentation of the invention

It is also an object of the present invention to provide a solution for SmartBuildings which provide electrical power to the power distribution grid feed, at least contributing to static grid stabilization.

In the case of static grid stabilization, at the request of the grid operator, inverters must be able to feed inductive or capacitive reactive power into the grid in order to balance the wind power balance in the grid and keep the grid voltage in the medium-voltage grid stable.

In addition, the active power should be automatically reduced depending on the mains frequency. This is done according to the medium voltage directive via a static characteristic (40% per Hz) from leaving the normal frequency band at 50.2 Hz (upper frequency limit of the primary control) to the shutdown of the generating unit at a frequency above 51.5 Hz. This behavior was taken from the transmission code 2007, thus Medium-voltage installations behave with respect to the global size of the grid frequency as well as power plants on the transmission grid.

In contrast, dynamic network stabilization provides voltage maintenance for small, manageable network faults to prevent unwanted concurrent shutdown of the feed-in power and thus whole network crashes. Thus, in accordance with the medium-voltage directive, the generating installations must not simply switch off themselves in the event of faults in the grid and must provide a defined short-circuit current in the event of a short-circuit in the public grid.

In both static and dynamic network stabilization, SmartBuilding's producers should be actively involved in the operation of the smart grid, and producers should be involved in the smart building's internal optimization processes and would not be able to grid-stabilize the smart grid.

It is therefore the object of the present invention to balance these conflicting requirements.

This object is achieved by a method having the features of claim 1, in which - in the energy distribution network, at a location in the area from the network connection point of the building to the energy distribution cabinet of the building, the voltage and / or at a location remote from the building's grid connection point in the area up to the nearest to the building transformer of the energy distribution network Current are measured, - the voltage measured values are compared with a predetermined voltage-real and -blind characteristic which ensures grid stability and / or the current measured values are compared with a predetermined grid-power and reactive-power characteristic which ensures the grid stability, - the difference between measured values and characteristic curve to the energy management system be forwarded and - calculated when exceeding the specified by the reactive power characteristic or by the active power curve area the energy management system, which components of the building it must change its power to return to the range within the reactive power characteristic, and the power change is performed by the component.

The voltage measurement is carried out according to the invention near the building, ie somewhere between the network connection point (including this) and the energy distribution cabinet of the building. The current measurement should not be made at the grid connection point of the building, but at a point in the area to the next transformer, or where a high power load is expected.

The change in performance may be provided by a component of the building or by several components.

By having the energy management system calculate how to maintain the external specified reactive power characteristics, the needs of the building can be considered accordingly.

In the case of voltage measurement, it is advantageous if the voltage at the grid connection point from the building to the power distribution network is measured. In this case, but also generally, either only the voltage of one phase is measured or an average value is formed over all phases, depending on whether one can assume that there is no or at least an unequal load on the phases.

In the case of current measurement, it is advantageous if the current is measured at the nearest transformer and / or at the highest loaded line segment of the network string from which the building is supplied. The most heavily loaded conduit segment, in the case of negligible production power in the strand of interest, is typically the first conduit segment from the transformer. With high penetration with generators, this may also be another line segment. In general, either only the current in one phase is measured, or an average value is formed over all phases, depending on whether there is no or at least an uneven loading of the phases.

For the distribution system operator to be able to change the effective and reactive power characteristics on a daily or seasonal basis, a variant of the invention provides that the power characteristic curves stored in the energy management system are changed by the operator of the energy distribution network via a data connection to the energy management system, in particular running.

Another problem in low-voltage networks is the uneven loading of infrastructures and thereby overloading or violating the voltage limits of individual phases. If the method according to the invention is also to be used for reducing such asymmetries in the load, it is provided in the case of the voltage measurement that the voltage of several phases, in particular of all three phases, is measured and in the case of an unequal

Load balancing the energy management system calculates from which phases real or reactive power is reduced or increased to reduce the unequal load distribution, and corresponding switching of components of the building from one phase to another.

Similarly, in the case of current measurement, it can be provided that the current is measured in several phases, in particular in all three phases, and in the case of an unequal load distribution on the phases, the energy management system calculates from which phases active or reactive power is reduced or increased in order to reduce the unequal load distribution. and corresponding switching of components of the building from one phase to another.

The component of the building whose power is changed, may be about an inverter of a photovoltaic system.

A possible device for carrying out the method according to the invention is characterized in that - in the energy distribution network near the building, ie at a location remote from the building's grid connection point in the area up to the transformer of the energy distribution network closest to the building, at least one measuring device for measuring current and / or at one point in the area from

A power management system is provided, with which the voltage measured values are compared with a predetermined, the grid stability guaranteeing voltage-real and reactive power characteristics and / or the current measured values with a given, the grid stability can be compared with the energy management system when the current or reactive power characteristic curve is exceeded

Area can be calculated, which components of the building must change their power to return to the range within the reactive power characteristic, and data connections of the energy management system to the components are provided to perform the power change through the component.

Further embodiments of the device according to the invention are given in the dependent device claims.

The invention offers the following advantages:

Because the scheme is related to performance, if multiple buildings in a network section of the power distribution network operate according to the invention, several or even all of the buildings can work together to stabilize the network, but at the same time contribute only in accordance with their performance. There is thus no overshoot of the system, as would be the case with an uncoordinated rule.

By matching the setting parameters of the individual building energy management systems, it is possible to ensure that buildings with "weak" grid connection points are not disproportionately influenced in the internal optimization by requiring constant adjustments of the performance.

With the method according to the invention, the available network capacity of the energy distribution network can also be better utilized. More expensive expansion due to increased feed-in of renewable producers with low full load hours (which causes a high power load) or due to the increase in load due to the substitution of other forms of energy can be avoided or delayed.

If similar guidelines were to be issued for smart buildings, such as the German medium voltage directive, they could be complied with by the present method.

The new functionality of the Smart Buildings can lead to an increase of the added value by the energy management system, in that the contribution to the network stability is offered to the network operator in return for compensation.

Brief description of the figures

To further explain the invention, reference is made in the following part of the description to the figures, from which further advantageous embodiments, details and further developments of the invention are to be taken. Show it:

1 is a diagram of a device according to the invention,

Fig. 2 shows an example of a combined active and

Reactive power characteristic as a function of the voltage,

Fig. 3 shows an example of a combined active and

Reactive power characteristic as a function of the current.

Embodiment of the invention

Fig. 1 shows an example of the scheme of a

Energy management system 1 of a building 2, namely a smart building, which is connected to the energy distribution network 3.

So-called energy management generally coordinates the procurement, conversion, distribution and use of energy, in this case electrical energy. Coordination is anticipatory, organized, systematic and taking account of environmental and economic objectives.

An energy management system is the implementation of energy management and the realization of the necessary organizational and information structures, including the necessary technical measures, such as Software. An energy management system according to the invention therefore comprises at least one computer or a PLC with power management software as well as data connections (e.g., data lines) to information sources, meters and the components of the building 2 to be controlled.

Only one part of the energy management system 1 is shown here, namely the so-called Building Energy Agent (BEA) 4, which is generally realized by software. It communicates via data links (shown here generally with double-headed arrows) in information exchange with the individual components of the building, which are essentially subdivided into three groups: the consumers 5, the memories 6 and the generators (generators) 7. An input possibility 8 is provided for customer requests by means of which users of the building 2 themselves can influence the energy distribution in the building and for example start or stop the loading of memories 6 by the generators 7.

The BEA 4 is used to optimize consumers 5, storage6, generators 7 and possibly also the electromobility (eg in the form of a charging station for electric vehicles) by day-ahead deployment planning under external factors (meteorological data, market prices of the energy exchange (EEX), customer requests, ..). .).

The BEA 4 as well as the consumer 5, memory 6 and generator 7 components are also in communication with the smart meter 9 of the building 2. This indicates to the terminal user the actual energy consumption and the actual usage time and is integrated in the communication network of the energy distribution network.

These smart meters 9 are typically controlled by a microprocessor and can automatically transfer the collected data to the power company. Electrical power, here generally indicated by single-black arrows, from and to the power distribution network 3 is sensed via the power line measured by the smart meter 9 fed.

However, the BEA 4 is also connected to data sources outside the building 2, such as those for weather forecasts10 or for the energy market 11 (in particular relating to electricity price development). This allows the BEA 4 to plan when energy needs to be taken into the building 2 from outside (because, for example, no sunshine is to be expected and the photovoltaic system as generator 7 supplies less energy) or should (because the electricity price is currently low).

Essential to the invention, however, is a component of the BEA 4, which forms a formal access point to the energy distribution network 3, in particular to a smart grid, namely the so-called building-to-grid adapter for ensuring network stability, BGA-SN, 12 for short. SN 12 now become concrete critical network states, eg as a result of deviations from the day-ahead operational planning of the BEA4, actively prevented. The main objective is to prevent possible violations of the applicable standards for voltage limiting or overloading of the resources of the energy distribution network 3 and thus actively contribute to the protection of damage to components of the energy distribution network 3, such as transformers, to blackout prevention.

The BGA-SN 12 has a data connection, represented by a dashed arrow, using a first protocol PI for measuring the voltage and / or the current. With another data connection and using a second protocol P2, the BGA-SN12 is connected to the Building Energy Agent (BEA) 4, which in turn is connected to the distribution system operator 13 via a data link and using a third protocol P3.

For solving a U-problem by means of the BGA-SN 12, for example, the following is done: at the connection point (network connection point) of the building 2 to the power distribution network 3, a three-phase measurement of the voltage in a high resolution. For this purpose so-called power quality measuring devices or smart meters of appropriate suitability are required. The gauges transmit the data to the BGA-SN 12 with a first protocol PI (e.g., M-Bus Radio, MODBUS, IEC60870-5-104, ...).

Depending on the power consumption of building 2, the grid connection point is at grid level Seven (in the low-voltage grid), at grid level Six (low-voltage bus of the grid transformer) or at grid level five (in the medium-voltage grid). Depending on this, the subsequent settings for the operating system or active network management system are to be coordinated in the middle or lower voltage level.

Based on the medium-voltage directive concerning the type of possible influence of a network operator, the BGA-SN 12 ensures a fictitious P (U) / Q (U) characteristic curve for the smart grid according to FIG. 2. The distribution system operator 13 can influence the impressed characteristic curve via the third protocol P3. by changing the characteristic points.

As can be seen from Fig. 2, it is the need for a four-quadrant operation for effective and reactive power. Through the BGA-SN 12, the BEA 4 reduces or increases the real or reactive power according to the voltage value at the node. If necessary, suitable temporal averaging is still necessary from the temporally high-resolution voltage values. When the invention variant is used to compensate for uneven loading of the individual phases, a single measurement is the

Voltages are required in each phase - otherwise they could also be averaged over the phases.

In Fig. 2, an example of a relative characteristic is given. After appropriate parameterization, however, an absolute characteristic can also be impressed. The quotient of voltage difference AU (measured voltage U minus rated voltage U rated) and nominal voltage U rated is plotted on the horizontal axis, while the quotient is plotted on the vertical axis

Reactive power difference AQ (measured reactive power Qminus nominal reactive power Qnenn) and rated reactive power Qnennsowie the power difference AP (measured electric power P minus rated power Pnenn) and nominal power Pnenn.

Specifically, the BGA-SN 12 reports the currently required active or reactive power change to the BEA 4 via protocol P2 according to the set characteristic. It decides according to the instantaneous optimization by which components of the building 2 these changes are to be made in order to disregard the building-internal optimization as little as possible. To pass on this information, the protocol P2 is also used.

The protocol P3 for data transmission between BEA 4 and distribution network operator 13, specifically its active network management system, serves to provide the

Not only to change characteristic points one-time through engineering, but also dynamically (for example, daily or seasonal).

However, the BGA-SN 12 can also contribute to the solution of an I-problem: for this expression, the same requirements apply to the solution of a U-problem, it follows analogously, only that instead of a voltage measurement, a current measurement takes place by means of the protocol PI.

Based on the medium voltage directive concerning the type of possible influence of a network operator, the BGA-SN 12 ensures a fictitious P (I) / Q (I) characteristic curve for the smart grid according to FIG. 3. The distribution system operator 13 can influence the impressed characteristic curve via the third protocol P3. by changing the characteristic points.

As can be seen from Fig. 3, it is the necessity of four-quadrant operation for real and reactive power. Through the BGA-SN 12 the BEA 4 reduces or increases the active or reactive power according to the current value at the measuring point. Optionally, from the time-high-resolution current values still a suitable temporal averaging necessary. If the invention variant is used to compensate for unequal loading of the individual phases, a single measurement of the current in the individual phases is required - otherwise it could also be averaged over the phases.

In Fig. 3, an example of a relative characteristic is given. After appropriate parameterization, however, an absolute characteristic can also be impressed. On the horizontal axis the quotient of current difference ΔΙ (measured current I minus rated current Inenn) and nominal current Inenn is plotted, on the vertical axis the quotient of power difference ΔΡ (measured electric power P minus nominal power Pnenn) and rated power Pnenn.

The two forms of voltage or current measurement can be separated depending on the network characteristics, in the case of suburban networks, where U and I problems occur in combination, can also be used in combination.

If there are asymmetries between the individual phases of the power dividing network 3, in the case of a U-problem, after measuring the voltage of all three phases of the BGA-SN 12 may

Suggest how to reduce which effective or reactive power and which should be increased. According to the invention, the BGA-SN 12 provides only one suggestion, e.g. Reduce active power to 20KW on phase LI. The BEA 4 decides by optimization then how the proposal is implemented. The components controlled by the BEA 4, such as e.g. The inverter of the photovoltaic system, for example, have a physical switching device (e.g., three-phase photovoltaic inverters) that can change the phase occupancy.

In the case of an I problem, the procedure is analogous, but instead of the voltage, a three-phase current measurement is used to reduce or even balance out any asymmetries in the utilization in critical network components (transformer, certain highest load line sections).

List of Reference Signs: 1 Energy Management System 2 Buildings (Smart Building) 3 Energy Distribution Network 4 Building Energy Agent (BEA) 5 Consumers 6 Storage 7 Generators (Generators) 8 Input Options for Customer Needs 9 Smart Meters (Smart Meters) 10 Data Source for Weather Forecasts 11 Data Source for the Energy Market 12 Building grid-to-grid adapter to ensure network stability (BGA-SN) 13 distribution system operator (operator of the power distribution network) PI first protocol P2 second protocol P3 third protocol

Claims (14)

1. A method for stabilizing an energy distribution network (3) including an energy management system (1) at least one building (2), wherein - in the energy distribution network (3) at a point in the range of the network connection point of the building to the energy divider cabinet of the building, the voltage and / oran Current measured in the area up to the building closest transformer of the energy distribution network (3), - the voltage measured values compared with a given, the grid stability ensuring voltage-power and power curve and / or the current measurements with a predetermined, the grid stability ensuring current-Wirk and the reactive power characteristic curve are compared, the difference between the measured values and the characteristic curve is forwarded to the energy management system, and in the event of the energy being exceeded by the reactive power characteristic curve or by the active power characteristic curve In the given area, the energy management system (1) calculates which components of the building must change their power in order to reach the area within the active or non-active area. Reactive power characteristic to return - and the power change is performed by the component (7). A method according to claim 1, characterized in that the voltage at the grid connection point is measured from the building (2) to the power distribution network (3). A method according to claim 1 or 2, characterized in that the current is measured at the nearest transformer and / or at the highest loaded line segment. Method according to one of claims 1 to 3, characterized in that the active and reactive power characteristics stored in the energy management system (1) are changed by the operator of the energy distribution network (13) via a data connection to the energy management system (1). Method according to one of claims 1 to 4, characterized in that the measurement of current and / or voltage is carried out on a single phase or on several phases with subsequent averaging over the phases. A method according to any one of claims 1 to 4, characterized in that the voltage of several phases, in particular of all three phases, is measured and, in the case of unequal load distribution on the phases, the energy management system (1) calculates from which phases effective or reactive power is reduced or increased to reduce the unequal load distribution, and corresponding switching of components (7) of the building (2) from one phase to another. Method according to one of claims 1 to 4 or 6, characterized in that the current is measured in several phases, in particular in all three phases, and in case of an uneven load distribution on the phases, the energy management system (1) calculates which phases are active or reactive power is reduced or increased to reduce the uneven load distribution, and a corresponding switching of components (7) of the building (2) from one to another phase takes place. A method according to any one of claims 1 to 7, characterized in that the component of the building whose power is changed is an inverter of a photovoltaic system. 9. A device for carrying out a method according to one of claims 1 to 8, wherein - at least one measuring device in the energy distribution network (3) at a location from the network connection point of the building (2) in the area up to the building (2) nearest transformer of the energy distribution network (3) Measuring current and / or at a location in the area from the grid connection point of the building (2) to the energy distribution cabinet of the building (2) is provided at least one measuring device for measuring voltage, - an energy management system (1) is provided, with which the voltage measured values with a predetermined, the Power stability and performance characteristic curve can be compared and / or the current measured values can be compared with a given current stability and performance characteristic guaranteeing grid stability, with the energy management system (1) if the range specified by the active or reactive power characteristic is exceeded s it can be calculated which components (7) of the building (2) need to change their power to return to the range within the reactive power characteristic, and - data links of the energy management system to the components are provided to perform the power change by the component (7). 10. The device according to claim 9, characterized in that the measuring device for measuring the voltage at the network connection point from the building (2) is provided to the energy distribution network (3). A device according to claim 9 or 10, characterized in that the measuring device for measuring the current is provided at least at the nearest transformer and preferably additionally at the highest loaded line segment. Device according to any one of Claims 9 to 11, characterized in that a data link is provided between the distribution system operator (13) and the energy management system (1) to enable the active and reactive power characteristics stored in the energy management system (1) to be determined by the distribution system operator (13 ) can change constantly. Device according to one of claims 9 to 12, characterized in that the measuring device for measuring the voltage and / or the current is connected to a plurality of phases, in particular all three phases, and the energy management system (1) is designed such that it can calculate from which phases active or reactive power is reduced or increased to reduce an uneven load distribution, and the components (7) of the building (2) via a switching means to change the phase assignment. 14. Device according to one of claims 9 to 13, characterized in that the component of the building (2) whose power is variable by the energy management system (1) is an inverter of a photovoltaic system.