EP3251077A1

EP3251077A1 - Method for improving the capacity utilization of a low-voltage network

Info

Publication number: EP3251077A1
Application number: EP16701925.6A
Authority: EP
Inventors: Tobias GAWRON-DEUTSCH; Alfred Einfalt; Jan Wieghardt; Yaroslav BARSUKOV; Jürgen Götz; Nicolas GÜMBEL; Ralf MOSSHAMMER
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2015-01-29
Filing date: 2016-01-26
Publication date: 2017-12-06
Also published as: WO2016120248A1

Abstract

The invention relates to a method for improving the capacity utilization of a low-voltage network (1, 2) using a communications network (13) between components of the low-voltage network, - controlled components (4, 6-11) recurrently generating and supplying load predictions to a central computer (12), - said central computer (12) producing a network condition prognosis from these load predictions and forwarding it to the controlled components (4, 6-11), and - the controlled components (4, 6-11) changing their load profile based on the network condition prognosis.

Description

description

Method for improving the utilization of a

Low voltage network

Technical area

The invention relates to a method for improving the utilization of a low voltage network using a communication network between components of the

Low voltage network.

Low voltage grids are part of the electricity grid

Distribution of electrical energy to most of the final electrical consumers consisting of low voltage equipment. To avoid voltage losses are

Low-voltage networks in the spatial extent limited to a range of some 100 m to a few kilometers. They will therefore be regional over

Transformer stations from a parent

Fed medium voltage network. They are commonly used in Europe with a mains voltage of 230 V (between each

Outer conductor and the neutral conductor) or 400 V (between the three outer conductors), but in any case only up to 1000 V.

operated. Rated power of individual

Local grid transformers may vary depending on the destination grid planning of the respective distribution system operator, but are typically 250 or 400kVA for rural areas and 630 or 800kVA for inner city areas.

The term low-voltage network in the sense of this invention designates a part of the distribution network, ie one

Section that is powered by a particular local power transformer with electrical energy.

Components of the low-voltage network can be:

Generators (eg photovoltaic systems, Small wind turbines), storage (eg batteries, heat pumps), eg charging stations for electric vehicles, flexible consumers (eg electric storage heaters, buildings with and without building automation system and

corresponding actuators (= converters or drive elements, convert electrical energy into mechanical motion or other physical quantities (eg pressure or temperature)) and network resources (transformers, lines,

Fuses, measuring devices such as smart meters, ...).

State of the art

The classical grid operation in the electricity supply is due to the increasing penetration of decentralized, usually renewable, power generation plants (DEA, usually in the power range from 3 to 100 kW) before large

Challenges posed. Added to this is the development of electromobility and thus an increase in the substitution of other forms of energy transmission with electricity. The so-called "smart grid" will be the solution for this

Seen problems. The smart grid or intelligent power network includes the communicative networking and control of power generators, storage, electrical consumers and network resources in energy transmission and power

Energy distribution networks of the electricity supply.

In the future, so-called "smart buildings", also referred to as smart 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 included, or about the charging infrastructure for electric vehicles. The building becomes "smart" or intelligent through the use of a modern building automation system.Building automation encompasses the entirety of monitoring, control, and control systems

Optimization facilities in buildings. The aim is,

Functional sequences independent of components across components (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 must therefore optimize their own requirements for electrical and thermal energy for the individual components of the building, create local (building-related) forecasts and have flexible tariff specifications that have market- or network-specific proportions.

consider.

In electricity generating plants> 100kW is about 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 generation plants on their own for static and dynamic grid stabilization

need to contribute. Similar requirements could therefore be met in future by smaller electricity generation plants, such as those in smart buildings.

In addition, distribution grid operators in Germany can restrict the decentralized generation of electrical energy if the network constraints require it. The current trend in decentralized power generation and the parallel delay in grid development make it likely that this will be increasingly used. At the same time, the energy producing units are in increasingly complex contexts, e.g. one

Combined heat and power plant generates electrical energy and heat for a district heating network and / or it is in addition to Water treatment used. However, any intervention of the distribution network operator of the electrical network is blind (with regard to, for example, the combined heat and power plant), so that unwanted cascades can arise. So can about the

Network operator of the electric distribution network

Cogeneration plant prescribe a reduction in the supply of electrical energy, with the result that less district heating is supplied, but by the operator of the

District heating network is not desired or intended.

One problem to solve is that of the outside

compulsory regulatory throttling of energy for as long as possible delay. A low voltage network has various active components that are used in the

Working together low voltage grid. There are several types of consumers, producers and hybrids. The

Connected buildings can not have meters that can be read remotely, equipped with a so-called "smart meter" or even equipped with a building management system.There is also the distribution system operator who operates a possibly adjustable local network transformer (RONT) and thus the relevant low-voltage network Together, they form the local branch, in which the network boundary conditions must be adhered to.Prosregional operate so-called Virtual Power Plants (VPP), which buy and sell electrical energy regardless of the local situation.

None of the above components can be any

Correct network problems without throttling. The VPP knows the local networks and thus the objective

Low voltage network not. The distribution system operator knows neither the producers' feed-in schedules nor the contracts between the producers and the VPPs. It can be in the case of throttling so disadvantages in terms of

Compensation energy costs for individual market participants or the VPP operator result because the planned timetables can not be met. On the other hand, the Timetables of the VPP, which have not yet been considered in the strategic planning of the low voltage grid, will cause network congestion that will lead to an overload of the

Low-voltage network.

So far, e.g. The inverter is equipped with a P / Q feed-in limitation which prevents too much power from being fed into the low-voltage grid in the event of a local limit violation. Thus, although the local boundary conditions are then ensured locally, but it is not certain that the throttling of this

Component is sufficient, nor that not too strong

is throttled and thus less energy is gained as possible.

An attempt to disentangle the market and to disentangle the network supervision represents the so-called "network traffic lights"

States red, yellow and green reflect the respective

Network state. The individual components, in particular the generators, can only be in the green state, where there are no restrictions from the network view and all market mechanisms can be used without restriction, or in the state red, where the network constraints demand hard requirements for the supply and thus local market mechanisms for a limited time are restricted, work. In the yellow state, within the network boundary conditions, a market-based

Optimization of the utilization of the low-voltage network

be made, so an optimization of the

individual components (e.g., the producer in the

Low-voltage grid) or the energy supplied to the individual market participants (for example VPP, ONS) with regard to the currently valid energy price.

This task of optimizing in the yellow state could now be transferred to the VPPs. However, this is not expedient, because it allows all market participants in this

Low-voltage grid would dictate to whom they need to sell their energy. If more than one VPP in the considered low voltage network (= a branch of the

general low-voltage network), they would have to work together, even if they were different

Operated by market participants. This mixture of market-oriented and network-oriented behavior with several participants can not be separated and harbors clean

regulatory issues in terms of the

Unbundling (separation of network and distribution in

Energy supply company).

An intermediate stage in which attempts are made without hard specifications to make optimum use of the resources and, despite strong feed-in from DEA, to comply with the network boundary conditions, does not yet exist.

Alternatively, there is the possibility of centrally coordinated throttling of the producers by the grid operator. However, this can not take into account the local conditions of the producers.

Presentation of the invention

The aim of the present invention is to provide the technical

Meet the requirements of the low-voltage grid and also, if possible, the economic aspect

consider. The fulfillment of the technical task includes compliance with the network constraints and the guarantee of the permanent power supply of the

Consumer. The economic aspect implies compliance with the utilization of the low-voltage grid (for example by the VPP, producers or consumers) so that the individual components are as economical and efficient as possible

can maximize profit. For this, the individual components must be able to communicate with each other.

This object is achieved by a method having the features of patent claim 1, - where of controllable ("intelligent") components

repeatedly supplied by these self-generated load forecasts to a central computer,

- The central computer from these load forecasts

Network state forecast created and sent to the controllable

Sends components, and

- that the controllable components are based on the

Network state forecast change their load profile. With controllable components are so-called

"Intelligent" components referred to, which has its own controller (usually in the form of software) of the

Have load pick up from the low voltage network or the load delivery to the low voltage network, e.g. virtual

Power Plants (Virtual Power Plants, VPP), photovoltaic systems and their storage, small wind turbines, smart meters or smart buildings.

With the invention, a kind of pre-stage network protection can be achieved, which essentially consists of a central computer

(computerized system), e.g. is housed in a distribution station of the low voltage network, with a

Communication unit exists. Firstly, it supports the distribution system operator in predicting the network situation in the future by collecting production and consumption forecasts of the controllable producers and taxable consumers connected to the low-voltage grid. Secondly, it may prevent the taxable producers and consumers connected to the low - voltage grid from future intervention of the

Distribution system operator warn. Producers and consumers can then assess the consequences of such an intervention and take timely countermeasures. If e.g. of the

Distribution system operator wants to throttle the supply of energy via the transformer of the low-voltage network in the superimposed medium-voltage network at a given time, can from this point on more energy from producers in the low-voltage network or from storage in the Low-voltage network can be fed, and / or the

Load reduction of a smart building can be reduced or postponed to later. The network state forecast may be e.g. as a result, the states of the low voltage network provide similar to the network traffic lights: the network may be in the green state, where there are no restrictions from the network view, or in the state red, where in some or all network nodes there are injuries

Network boundary conditions exist. In the yellow state sees the

Network state forecast a red state in the future. A network state forecast consists e.g. be used from a set of network nodes for each existing time series or created by substitution value generation based on available data time series. The most important time series are the load curve (feed-in power and / or consumption), the expected voltage and the traffic light levels. If required, other time series such as e.g. Current and thermal load of the cables / cables are included in the grid condition prognosis.

The central computer notifies all controllable

Components about the created grid state forecast and when e.g. With shutdowns of the low-voltage network is expected. This ensures grid stability and, secondly, provides grid operators and energy suppliers with planning security. All thus have an interest in participating in the method according to the invention.

The mesh condition forecast can be of varying complexity

be carried out: it can be aggregated about only the load predictions supplied by the individual controllable components.

It can also be provided that from the central computer for further, non-controllable components a - especially generic - load profile created and this in the

Net State Forecast is recorded. This can also "non-intelligent" components, such as households or buildings without smart meter, to be considered in the grid condition forecast.

It is also beneficial if the grid condition forecast based on the load predictions of controllable

Components is created, supplemented by forecasts based on weather data and / or historical data. This makes it possible to refine the grid condition forecast.

Weather data allow the central computer, the

Injection of photovoltaic and small wind turbines predict if they do not already contain the weather data in their load forecasts. Due to weather data (e.g., outside temperature curves) and / or from

historical data (previous load recordings or loads on days with the same or similar weather data or days of the same date) can predict the consumption of non-taxable consumers.

If, when creating the network state forecast, the

Network topology is taken into account, this has the advantage that much more selective individual controllable components can be selected for the solution of the network bottleneck. Thus, as a further constraint, the power loss in the network can be considered.

The central computer is for a low voltage network

(Low-voltage network in terms of this invention disclosure) responsible. Conceptually, he is in the

Local network station next to the transformer of the

Low-voltage network. This has the advantage that the computer is connected directly to the controller of the transformer and, in the case of Powerline Communication (PLC), the data from the smart meters and possibly also the

Building management systems (more precisely their

Energy Management Systems = Customer Energy Management

Systems) directly from the PLC modem. The advantages of this setup are the proximity, the reduced distance communication and the fact that the failure of one machine does not mean the whole

Area of influence of the distribution system operator, but only the comparatively small low-voltage grid. The disadvantage of this lineup is the large one

Number of additional hardware components to maintain. An alternative is to combine several central computers of different

Low voltage networks, e.g. through virtualization. Ideally, the virtualization computer is located at a network-topologically useful node, such as in a substation. For example, in the medium-voltage substation, the control units are located for all connected

Low-voltage networks. It is of course also possible to connect all low - voltage networks in the control room of the

Distribution system operator together. The technical implementation of the summary of tasks of computers is not limited to virtualization. It is only important that each low-voltage network is treated separately by the others.

When the central computer is accessible from the controllable components (e.g., the building management system or the

Energy management system for photovoltaic systems) in

regular intervals of these self-created

Catching up load forecasts can always be a current one

Network state prognosis are calculated, with the time intervals best correspond to the times in which experience has shown that it must respond to changes in the low-voltage network. The time intervals are preferably in the range of 15 minutes to one hour. A higher clocking brings the need for more powerful computers in the

Building management systems as well as a better

Communication connection and thus higher costs. On the other hand, there are the network boundary conditions, which tolerate a certain overshoot of the limits over several minutes. Thus, the higher costs would be at a

Time interval of less than 15 minutes only a comparatively little improvement in the overall system. The longer it takes to re-evaluate the situation, the more drifting forecasts and actual conditions drift apart and decisions based on outdated information are made.

The invention also relates to a system for carrying out the method according to the invention, comprising

Communication network between components of

Low-voltage network and a central computer, with controllable components are provided with which

repeatedly from these self-generated load forecasts can be delivered to the central computer, and wherein the central computer is designed such that it can create a network state forecast from the load forecasts and send to the controllable components, and that the controllable components based on the network state forecast their load profile can change. The invention realizes a first

communication-based, cooperative network protection, which prevents the harsh crackdown (e.g.

Low-voltage network) by providing

Information in the form of network state forecast largely prevented or reduced. Can the penetration despite

Network state forecasting can not be prevented so are

at least all controllable components or all am

Low voltage network stakeholders prepared for it. For example, each feed-in node may have its profit

maximize with the information, when he probably can not keep his contracts with a supraregional VPP due to network problems. The economic damage as a result of penetration can thus be minimized.

The network protection according to the invention is regional, since it is a small part of a low-voltage distribution network

takes care. The concept is based on the fact that the individual Components information not only about their current state, but also about their schedules (ie their

planned future load profiles). The invention is a pre-stage network protection, which the

Although low-voltage network protects, but intervenes before the classic network protection (for example, based on

Fault current analysis) must act.

In classic network protection, fault currents are interrupted quickly and as selectively as possible. Protection devices of this type are used in the model of the network traffic light in the red state. The invention allows the efficient utilization of

Equipment of the low voltage network up to the limits of the nominal load capacity by cooperative behavior of the

Components of the low-voltage network. From the central computer can with the network state forecast also the

Network edge conditions (e.g., the nominal load capacity) to the

Components are sent so that they can be taken into account by the components, so are not exceeded.

Due to the fact that the method or system according to the invention does not exist on already existing control levels, such as the

classical network protection or the intelligent local network station, builds up, it does not affect the orderly

Operation of these elements. The use of the invention can make the low voltage grid more operable, a

Deterioration is not possible because then the classic electrical network protection would take effect.

Brief description of the figures

To further explain the invention, reference is made in the following part of the description to the figures, from the further advantageous embodiments, details and

Developments of the invention can be seen. Show it: Fig. 1 is a schematic representation of two conventional

Low-voltage networks,

Fig. 2 is a schematic representation of two

Low-voltage networks according to the invention,

3 is a flowchart for the method according to the invention in connection with the different ones

Network conditions according to the so-called network traffic lights

Embodiment of the invention

Fig. 1 shows an example of the scheme of two similar low-voltage networks 1, 2, which are supplied via an energy distribution network 3 and each a local power transformer 4 with electrical energy. Each low-voltage grid 1, 2 has non-controllable components, such as buildings 5 or households, and controllable components, such as smart buildings 6 (intelligent buildings - both residential and

Commercial buildings), small wind turbines 7, photovoltaic systems 8, charging stations of electric vehicles 9, smaller

Manufacturing plants, farms,

Combined heat and power plants 21, larger cooling systems 20, buildings with battery storage 19. All components of the respective

Low-voltage network 1, 2 are connected via electrical lines 10 with each other and with the local power transformer 4. The electrical lines 10 themselves can also for

Data transmission between the individual components are used (Powerline Communication, PLC). Smart Buildings 6 have an energy management system that generally coordinates the procurement, conversion, distribution and use of energy, in this case electrical energy. Coordination is foresighted, organized, systematic and taking into account environmental and economic objectives. It includes organizational and information structures including the necessary technical measures such as Software. One

Energy management system therefore includes according to the invention at least one computer or a PLC with energy management software as well as data connections (eg data lines) to information sources, measuring devices and the to be controlled

Components of the building.

Furthermore, in FIG. 1, two virtual power plants VPP1, VPP2 are provided, each with

Components of various low-voltage networks 1, 2 are connected, namely in this example with decentralized power generators (photovoltaic 7, wind turbines 8,

Cogeneration Plant 21 or Smart Buildings 6, if they also have generating / storage facilities). A virtual power plant is an interconnection of decentralized - generally relatively small - power generation units, such as photovoltaic systems, small hydropower plants and biogas plants, but also small wind turbines and mini or micro combined heat and power plants to a network that can provide demand-driven electrical power. The power plant is called virtual because it has more than one location. The power generation units of a virtual

Power plant VPP1, VPP2 are interconnected via their own data links 11.

If, then, a network problem (for example, very strong overvoltage across a plurality of power supply circuits shown in FIG

Minutes) occurs in the first low-voltage network 1, the controllable local power transformer 4 is first adjusted to the lowest level. In the example, this is not enough and the distribution system operator must prescribe a reduction of the feed-in power to the systems that can receive the signals (Smart Buildings 6 in this example).

Otherwise, he violates the network conditions and does not meet his quality requirements. In extreme cases, this can lead to a total ban on feed-in (especially if many feed-in systems can not handle this signal). The affected plant operators can therefore not comply with their pre-negotiated supply contracts with the VPP operators. In Fig. 2, the same system as shown in Fig. 1, but has in Fig. 2, each low-voltage network 1, 2 via a central computer 12, with the help of the

inventive method is performed. The central computer 12 is connected by a communication network 13 to the individual components of the low-voltage network 1, 2

connected. The communication network 13 may be in a

Embodiment of the electrical leads 10 of the

Low-voltage network 1, 2 exist, so that a power line communication (PLC) is realized. However, for the method according to the invention, also separate data connections can be made or other existing data connections (for example from smart meters) can be used.

Again, the same starting position applies: the overvoltage is very strong in the network and can by changing the

Trafostufen alone can not be compensated. In contrast to the previous example, here the smart buildings 6 and generating plants 7, 8, 21 report their timetables, which they have negotiated with the respective VPP operators of the virtual power plants VPP1, VPP2, to the central computer 12 in the respective local network station. For example, at 11am, the buildings and power plants send the

Infeed timetable for the next day (0-24h). This consists, for example, of a feed-in power in watts for each 15-minute time window (ie 96 values). In the case of buildings, the value can also be negative - the building then draws energy from the grid. To get a more complete picture will not be pre-announced for all

connected components load profiles due to

historical data and standard load profiles.

These values can now be used to create an entire image over the next day (when to expect a peak load, when with a feed tip, what will it be, etc.). This then results in a

"Traffic light profile" - a time series every 15 minutes it is indicated in which state the

Low voltage grid is likely to be located. Over the next day, this grid condition forecast will become

updated and adapted to the real conditions. Each newly created network state forecast is transmitted to the buildings 6 and generating plants 7, 8, 21 in a timely manner.

The earlier, e.g. An intelligent building 6 knows that there is a risk that all feeders 7, 8, 21 will be shut down due to a strong overvoltage at 12 o'clock at the tip of the lunch feed, it may still change its timetables. One possibility would be to inform the virtual power plant VPP1, VPP2 in advance and apply this to the new one

Situation can adjust. The internal self-consumption optimization could also be changed so that the boiler is heated at noon, the refrigerator is cooled, the electric vehicle is charged, etc. Although this would be a suboptimal solution under an ideal network (= it never comes to a yellow or red network state), it may be better to risk a curtailment.

The consideration of the grid condition forecast is purely voluntary and only according to internal criteria. Therefore, it is a cooperative system. If each participant acts purely selfish and does not change his behavior, all participants will be punished by Abregein.

The inventive method can as follows in the

Traffic light model, which was developed as a basis for discussion in the National Technology Platform Smart Grids Austria

(see Fig. 3) are embedded. The states Red R, Yellow GE and Green GR then each reflect the different network state. The same is true for all local

Components.

The individual controllable components of the

Low-voltage network are here in power generator 7, 8, 21, electric vehicles or their charging stations 9, energy storage Divided 19 and 22 and flexible consumers 14. They are all controlled or controlled via control and regulation units 15, which are controlled by a higher-level control 16 (an object manager, eg an energy management system of a

Building) is monitored.

In the state yellow or green can be market-based

Energy services 17, so about market mechanisms, affect the higher-level control 16. In the green state, information about energy price and / or amount of energy can be exchanged and the controller 16 or the control and regulation units 15 send correspondingly different control commands to the controllable components. In the status yellow, information about energy price and / or electrical power can be exchanged and the controller 16 or the control and regulation units 15 send correspondingly different control commands to the controllable components.

According to the invention is now between the market-based

Energy services 17 on the one hand and the controller 16 and the control and regulating units 15 on the other hand, the central computer 12 connected, which in turn due to the network state forecast in turn changes in the load profiles of

performs controllable components.

In the network state Red R is provided that a

Safety device 18 with regard to electrical

Power or load (continuous arrow) sends control commands that also run on the central computer 12 according to the invention and from this now according to the

Modified network condition forecast and then to the

Control 16 and the control and regulation units 15 are forwarded. Only control signals of

Safety device 18 with high priority (dashed arrow) are without interference by the central computer 12 directly to the controller 16 and the control and

Control units 15 sent. The invention

operated central computer 12 should be such a case direct penetration, for example, by the distribution system operator (which corresponds to the accident and its treatment in Fig. 1) largely avoided. However, it is necessary to provide the possibility of direct penetration.

Reference sign list:

I first low voltage network

2 second low voltage grid

3 energy distribution network

4 local power transformer

5 buildings

6 Smart Building

7 small wind turbine

8 photovoltaic system

9 charging station of electric vehicles

10 electrical lines of the low voltage network

II Data connections of the virtual power plant

12 central computer

13 communication network

14 flexible consumers

15 control units for controllable

components

16 higher-level control

17 market-based energy services

18 safety device

19 energy storage

20 cooling system

21 combined heat and power plant

22 battery

GE power status Yellow

GR network status green

R Network status Red

VPP1 first virtual power plant (Virtual Power Plant)

VPP2 second virtual power plant (Virtual Power Plant)

Claims

claims

1. Method for improving the utilization of a

Low-voltage network (1, 2) using a communication network (13) between components of the low-voltage network,

wherein controllable components (4, 6-11) are repeatedly provided by the self-generated load forecasts to a central computer (12),

- The central computer (12) from these load forecasts created a network state forecast and to the

controllable components (4, 6-11) sends, and

- That the controllable components (4, 6-11) change their load profile based on the grid condition forecast.

2. The method according to claim 1, characterized in that the central computer (12) for further, non-controllable components (5) creates a load profile and this is included in the network state forecast.

3. The method according to claim 1 or 2, characterized

characterized in that the network state forecast, which is created on the basis of the load forecasts of controllable components (4, 6-11), is supplemented by forecasts based on weather data and / or historical data.

4. The method according to any one of claims 1 to 3, characterized in that the network topology is taken into account.

5. The method according to any one of claims 1 to 4, characterized

in that the central computer (12) is a separate computer in the local network station of the

Low-voltage network, or a virtualized computer is used for multiple low-voltage networks.

6. The method according to any one of claims 1 to 5, characterized

in that the central computer (12) of the controllable components (4, 6-11) in regular

Intervals from these self-created load forecasts overtakes.

7. System for carrying out the method according to one of claims 1 to 6, comprising a communication network (13) between components of the low-voltage network (1, 2) and a central computer (13), wherein controllable

Components (4, 6-11) are provided with which repeatedly from these self-created load forecasts can be supplied to the central computer (12), and wherein the central computer is designed such that it from the load forecasts create a network state forecast and to the controllable components (4, 6-11) and that the controllable components (4, 6- 11) can change their load profile based on the grid condition forecast.