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The RiesLing (Germany) and InovGrid (Portugal) projects - Pilot projects forinnovative hardware and software solutions for Smart Grid requirements

S. KÄMPFERABB AGGermany

P. G. MATOSEDP Distribuição

Portugal

C. KÖRNEREnBW Regional AG

Germany

J. BACKESEnBW ODR AG

Germany

SUMMARY

Europe has started its way into a new power supply system driven by the change towards renewableenergies, increasing energy efficiency and reliability. The operation and control of active distributionnetworks with a high share of DER will play a core role to cope with these challenges. The projects‘RiesLing’ and ‘inovgrid’ are developing solutions for the specific challenges in Germany andPortugal. Both projects will be introduced and the results will be compared.The project RiesLing (Projekt im Ries – Leittechnik intelligent gemacht, translated „implementationof an intelligent grid control in the Ries area“) focuses on the development and the practical test ofsolutions which according to the project partners represent core components of a Smart Grid. Theregion of its implementation is the Nördlinger Ries, a region in the north-western part of Bavaria andin close vicinity to the federal state of Baden-Württemberg. This area combines a maximum load ofaround 50 MW with a maximum generation of around 120 MW, mostly from Photovoltaic modulesand biogas fuelled engines. The RiesLing project has been initiated in mid of 2011. Its technicalimplementation is set up as four separate packages. Three of these packages are dealing withinnovative secondary equipment and communication solutions. Additional functions for the gridsupervision and control will be implemented in the fourth package, addressing power flow forecastand grid state estimation. The implementation phase is followed by a test period, lasting untilDecember 2013.With project inovgrid EDP Distribuição seeks to transform its distribution grid and position it as theanswer to several challenges, including: the need for increased energy efficiency; the pressure toreduce costs and increase operational efficiency; the integration of a large share of dispersedgeneration; the integration of electric vehicles and the desire to empower customers and support thedevelopment of new energy services. Beyond the technological aspects, project inovgrid is providingEDP Distribuição with the know-how and experience that will enable a smooth transition of theorganization to the Smart Grid paradigm. The main development of project, so far, has been theimplementation of a Smart Grid infrastructure in the Portuguese municipality of Évora. Theinfrastructure spans the entire municipality, reaching around 32.000 electricity customers with anannual consumption of approximately 270 GWh. This paper shares some outcomes of different studiesthat are being conducted, using the project as test site, including European projects, likeSuSTAINABLE (www.sustainableproject.eu), that develop advanced functionalities, like coordinatedvoltage control or technical virtual power plants, bringing additional distributed intelligence to thegrid, in particular low voltage, and that empower the DSO to cope with future and present challenges.It is consensus among the projects, that an increased grid observability, mainly at secondarysubstations and LV level will be the key for improving the grid capability in coping with highpenetration of renewables especially in terms of optimized grid utilization and selective, target-oriented invests in grid enhancement. In addition to that new tools for grid operation like predictiveload flow analysis will be the basis for more advanced and complex functionalities like coordinatedvoltage control, congestion management and virtual power plants.Despite some national peculiaritiesboth projects had similar major findings which can serve as basis for common European solutions.

KEYWORDSDistribution automation, intelligent secondary substations, voltage control, predictive grid operation,smart grids, distributed energy resources, renewable energy integration, smart metering

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IntroductionEurope has started its way into a new power supply system driven by the change towards renewableenergies, increasing energy efficiency and reliability. The operation and control of active distributionnetworks with a high share of DER will play a core role to cope with these challenges. Besides theincreasing amount of distributed generation, the regulatory frame conditions and decreasing costs forinformation and communication technology will most probably lead to more monitoring andautomation in the distribution grid. Main drivers for this development are benefits for grid operators,and other stakeholders, like the increased efficiency in operational processes or securing the requiredlevel of grid reliability. Major questions are the realization of automation functionalities in secondarysubstations as one key element in distribution grids, new functionalities in the grid control system forutilization of new monitoring and control functionalities for an advanced grid operation as well as theuse of measurements out of smart meters. The projects ‘RiesLing’ and ‘inovgrid’ are developingsolutions for the specific challenges in Germany and Portugal.

1 The RiesLing projectThe pilot project ‚RiesLing’ (Projekt im Ries – Leittechnik intelligent gemacht, translated„implementation of an intelligent grid control in the Ries area“) aimed the development of differentsolutions for the stepwise automation of secondary substations and advanced grid operationfunctionalities in the grid control system as well as the field test within the grid of EnBW ODR.Based on the new challenges for grid operators the following tasks occur, which are considered in theproject- Detection and remote indication of short circuits and pulse signals in case of earth faults

(compensated grid) in the MV grid for the localization and automated isolation and restoration inorder to reduce outage times

- Monitoring of the grid and equipment load in order to optimize assets and operation- Voltage regulation in the MV grid based on distributed measurements- Voltage regulation in the LV grid based on a power electronic voltage regulation unit and different

regulation algorithms including distributed voltage measurements using smart meters- Detection of congestions in the MV grid in advance based on load and generation forecasts- Management of these congestions by changing the topologyThe proposed solution concepts are based on an increased grid observability, new control functionsand new applications in grid operation, which are realized locally, i.e. distributed for instance in thesecondary substations or centralized in the grid control system.

1.1 Automation of secondary substations – increased grid observability and controlFor the automation of secondary substations optimized packages with standardized and modularfunctionalities were developed which are suitable for new stations as well as to equip existing stations.Core component is a standardized hardware platform for the secondary equipment for allfunctionalities, which can be used independently from the installed primary equipment and installedvery easily. According to the application different functional modules, e.g. for advanced softwareapplications like fault detection or different voltage regulation algorithms, can be added. This set ofharmonized equipment is completed by primary components for the realization of further controlfunctionalities and provides scalability for different retrofit and installation demands. This enables anefficient and stepwise automation of secondary substations without extensive engineering efforts.

In the first phase existing secondary substations were equipped with secondary technology in order toprovide measurements and signals to the grid control center. On the LV-side of the MV/LV-transformer the measurement of voltage, current, power and reactive power is provided. Voltageconnectors with piercing contacts, which are also used for the power supply, and simple split corecurrent transformers on the LV and MV side enable easy installation. In order to reduce the number ofmeasurements, the current measurement on one MV cable feeder is left out. One major challenge isthe measurement of the MV side voltage without the extensive installation of voltage transformers.This task is solved by calculating the MV voltage from the voltage and current measurement at theLV-side of the transformer based on an implemented transformer model, which considers the load

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dependent voltage drop and the according phase shift. With the MV current measurement the activeand the reactive power on the MV cable feeder can be calculated. With the resulting values also thepower flow on the not measured MV cable feeder is calculated. Based on a three feeder ring main unitall relevant values (V, I, P, Q) on MV and LV level can be provided with one voltage and two currentmeasurements.The measurement transducers for the MV level include also phase selective overcurrent detection, sothat they additionally act as a fault pass indicator. By using the LV voltage the direction of symmetricfaults can also be determined. For the localization of earth faults in the compensated grid the pulsemethod is used. Based on the periodic variation of the earth inductance a pulse signal is generated onthe zero sequence system current through the fault location, which can be detected.In the second phase existing secondary substations are additionally equipped with new ring main unitswhich include motorized load break switches and partly combined sensors based on capacitivedividers and rogowski coils. In the third phase a new intelligent compact secondary substation wasimplemented, which includes a power electronics based active voltage regulator (AVR). In case ofinterruptions of the power supply an UPS enables the communication of signals for the fault location.The UPS is integrated in the standardized secondary package and supplies also the MV switches.

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Ortsnetzstation (ONS)

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b) c)Figure 1: a) Technical concept (1 Measurement transducers; 2 RTU; 3 communication module; 4 UPS; 5motorized load break switches; 6 voltage regulation unit); b) automation package; c) smart station with AVR

1.2 Voltage regulation for the LV gridThe active voltage regulator is based on power electronic converters and is integrated at the lowvoltage side independently from the transformer. The power electronic module provides a steplesscorrection voltage which is injected by a series boost transformer. The correction voltage is based onthe actual grid voltage and the online set point from the RTU. In the project RiesLing three differentvoltage control methods were implemented. The first one comprises a fixed set point which isdetermined by the grid control system. In this case the regulation potential of the voltage regulator andthe available voltage band is not fully exploited. The voltage at critical grid nodes is not considered.The second method uses the smart meters as distributed voltage measurements in order to calculate anoptimized voltage set point. The voltage on critical nodes as well as the resulting voltage isconsidered. The exploitation of the voltage band is dependent on the selection of the measured gridnodes. The third method is based on load flow dependent voltage set point using a proportional factor.Therefore the power flow through the transformer is used as a local value in the secondary substation,so that no further measurements and the according communication infrastructure in the grid arerequired. The adjustment of the proportional factor determines the regulation behavior and theexploitation of the voltage band. Despite no direct information about the critical voltage is used, theexploitation of the voltage band is improved significantly compared to the fixed set point.

Figure 2: voltage regulation results: fixed set point, set point with distributed measurements, load flowdependent voltage set point (red: voltage at LV bus bar; blue: minimum and maximum voltage in the LV grid)

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Due to the voltage regulator more distributed generation units can be integrated into the grid withoutviolating the voltage band, which can avoid or delay traditional grid extensions.

1.3 New functionalities in the network control systemThe following new functionalities are realized within the RiesLing project:- Forecast of expected load and generation some days ahead- State estimation based on real measurements, forecasts of renewables and typical load profiles- Automated short circuit and earth fault location- Wide area voltage control with topology based assignment of measurementsThe automated short circuit and earth fault location is based on the processing of the fault signals fromthe secondary substations (directional short circuit detection and pulse detection for earth faults). Aftersuccessful location the remote controllable switches are used to automatically isolate the fault andreconfigure the grid for restoration.The wide area voltage control generates a control command for the on load tap changers of theHV/MV power transformers based on distributed measurements e.g. in the secondary substations. It isbased on a voltage-var-control function which is also able to control the reactive power. Thedistributed measurements are automatically assigned to the correct transformer according to the actualtopology of the grid.One core functionality is the state estimation and the predictive load flow calculation. For this purposea load profile is implemented for every secondary substation based on the analysis of the load profilesof different customer categories and their share of the station load. In a second step the total generationpower per station and generation type, mainly photovoltaic, is determined based on the forecasts. ThePV forecasts are provided as a normalized power value referring to zip code areas and available up to3 days in advance (‘3 days ahead’). The forecast time series are scaled according to the installed powerper secondary substation. Thus a generation forecast is calculated. The supervision of load andgeneration profiles generates the total power profile for the dedicated substation. Based on themeasurements these profiles are calibrated on feeder level and the resulting load flow including thenode voltages is calculated. The forecasts can be used to identify possible congestions or voltageproblems in advance. Violations will be reported by the system and can be solved by adequatemeasures like creating a switching sequence to change the topology or curtailment of DER.Additionally the predictive load flow can be used to plan maintenance and outages.

Figure 3: Load flow forecast and calibration

1.4 Communication infrastructureSecured, reliable and cost efficient communication is a crucial aspect in Smart Grid. Within theRiesLing project a communication service provider supplied a managed and secured communicationplatform, which is targeted to be a commercial product for grid operators. This platform is universaland transmits smart meter reading data as well as the substation control signals and the onlinemeasurements. One feature of the platform is a SCADA interface which provides the smart metermeasurements according to IEC 60870-5-104 and acts as a virtual RTU. Data security using a virtualprivate network (VPN) is implemented by the industrial partner, requiring no specific knowledge onthe side of the grid operator. Communication cost using commercial mobile IP providers is cost-

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efficient, but not buffered against interruption of electrical supply. For substations with higherrequirements on reliability communication interfaces connecting to two redundant grids (e.g. DSL plusGPRS) are implemented.

2 The inovgrid project

inovgrid is EDP’s umbrella project for smart grids. With project inovgrid EDP Distribuição seeks totransform its distribution grid and position it as the answer to several challenges, including: the needfor increased energy efficiency; the pressure to reduce costs and increase operational efficiency; theintegration of a large share of dispersed generation; the integration of electric vehicles and the desireto empower customers and support the development of new energy services. Beyond the technologicalaspects, project inovgrid is providing EDP Distribuição with the know-how and experience that willenable a smooth transition of the organization to the Smart Grid paradigm.

inovgrid is a distinctive project in the European landscape because it combines a reasonable size, interms of the number of customers reached, with a strong focus on the Smart Grid vision (as opposed toother projects, which are purely smart meter oriented). After compiling a catalog of all EuropeanSmart Grid projects, the Joint Research Center (JRC) of the European Commission has recognized theunique positioning of project inovgrid by choosing it as the single case study on which to base thedevelopment of its “Guidelines for Conducting a Cost-Benefit Analysis of Smart Grid Projects”[Report EUR 25246 EN]. Moreover, inovgrid has been labeled under the European Electrical GridsInitiative as a “Core Project”, showing the alignment with European targets.

EDP believes that smart grids have the potential to help DSOs address the technical challenges posedby new technologies, such as dispersed generation and electric vehicles, while contributing to the ever-present challenges of efficiency and quality of service. The evolution towards a smarter grid istouching a number of different areas at EDP Distribuição; with project inovgrid EDP seeks anintegrated approach to this change process.

The main development of project inovgrid, so far, has been the implementation of a Smart Gridinfrastructure in the Portuguese municipality of Évora. The infrastructure spans the entiremunicipality, reaching around 32.000 electricity customers with an annual consumption ofapproximately 270 GWh. Additionally, there are 140 Medium Voltage customers with an annualconsumption of 110 GWh. Industrial activities account for 57% of electricity use, while servicesaccount for 34% and agriculture and other activities for the remaining 9%. Currently the project isscaling up, and is expected to reach 150 thousand new customers in Portugal, as it is expanding to 7new locations.

2.1 inovgrid Architecture

From a technical perspective, the architecture of the system deployed in Évora includes the followingcomponents.

• EDP Box (EB)Installed in all low voltage customers (~32 thousand), offering advanced smart meterfunctionalities, such as real time readings on demand, load diagrams, voltage monitoring andremote services (connect/disconnect, contracted power and tariff setup, tampering alarms, etc.)The EDP box main features to perfectly integrate SMART GRIDS and AMM solutions are:

· Single and three-phase meters for direct connection to low voltage network;· Active and reactive energy and power measurement (consumed and produced);· Multi tariff and capable of operating simultaneously with 2 tariff structures;· Load profiling;· Maximum demand registration;· Power control management, with capability to remotely change maximum demand

threshold and connect/disconnect supply;

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· Demand management;· Events registration and alarms management;· Anti-fraud detection;· Quality of Service logging;· Integrated LAN communication module (PLC or GPRS) for communication with DTC

and central system;· Local communication interface to enable communication to in-house equipment

• Distribution Transformer Controllers (DTC)Installed in every secondary substation (about 300), acting as data concentrators and localmetering, monitoring and automation devices (PQ monitoring, MV switching, local sensors, etc.);The DTC is a local control equipment installed in distribution transformer stations, the maincomponents being a measurement module, control module and communications module. Its mainfunctions are: collecting data from EDP boxes and MV/LV substation, data analysis functions,grid monitoring and interface with commercial and technical central systems.DTC also acts as a data concentrator with PLC communication installed at secondary substation(MV/LV transformer), that by integrating multiple automation functions enables true smart gridsolutions from MV and LV network automation through street lighting, demand-sidemanagement, EV smart charging and micro-generation control.

• A communication network based on PLC and GPRS technologies, linking EBs and DTCs to headend systems;

• EV charging stations;

• Efficient public lighting systems, based on LED luminaries with advanced control.

Figure 4: inovgrid architecture

inovgrid embraces all the different aspects of the smart grid ecosystem, from the central informationsystems to the end users, from the smart meter to the electric vehicle charging infrastructure, and beingan open platform by construction it fosters innovation from all the participants in the ecosystem andprovides the favorable environment that allows the evolution and creation of new business models,services and products that will ultimately benefit the different stakeholders. There is a strong drive to

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push open and standards protocols, as well as interoperable equipment from different suppliers inorder to be able to arrive to a solution can be escalated and replicated not only within the EDPgeometry (already being addressed in Brazil and Spain) but also at broader level.

2.2 Outcomes and progress of inovgrid

By putting the inovgrid infrastructure into place EDP Distribuição is today able to have increased gridobservability in the municipality of Évora. From the DSO perspective before having the Smart Gridproject in place, it was not possible to have detailed information about the Low Voltage grid, asproblems had to be reported by consumers, who detected them, thus the DSO had a reactive approachto the LV grid management. Today it is possible to be proactive by receiving information from theSmart Grid infrastructure and acting upon it. The EDP Boxes installed in clients are also capable ofmeasuring volts and amps, and informing the systems in case some fault occurs. Besides that, the DTCcan monitor the secondary substation, and add increased observability over the grid. DTCs have fault-detection modules that allow also finding very efficiently where a network fault occurred and incooperation with other grid equipment isolate faults and restore service in some cases. Furthermore,the integration of all this new information in the company systems allows performing remoteoperations in customers’ premises, such as automatic disconnection of non-paying clients or changesin contracted power. These operations can be directed from the contact center, saving physicaldisplacement of field teams and customers, and contributing to a more efficient service.

Advanced Voltage Regulation in LV grid is also addressed, as the EDP Box has the capability tomeasure and communicate instantaneous power (active and reactive). This feature is key to implementan advanced voltage regulation system, which not only integrates the load information, but alsodistributed generation, allowing to properly implementing the best strategy for grid optimization.Local distributed intelligence based on the DTC is being implemented, so that the DTC has thecapability to adjust some network parameters in a coordinated way, so that voltage levels remainwithin acceptable limits. Some of this advanced functionalities are under development in Europeanprojects, that will leverage in the inovgrid project to demonstrate and validate its results, in particularthe FP7 project SuSTAINABLE (www.sustainableproject.eu) coordinated by EDP Distribuição. Thisprojects aims at maximizing RES integration in the grid using dispersed information that can be usedfor improved network management, increasing capacity for accommodating Distributed EnergyResources (DER). Having better information about grid state, renewable injection and load, allows tohave an optimized grid operation, and to come up with the best strategy to maximize the integration ofRES, maintaining security of supply and voltage at desired levels. Concepts as Virtual Power Plants(VPP) will play an important role within aggregation of DER, and will leverage on the informationcoming from the different assets. Still, it is the DSO that has to ensure the technical validation of thedesired operation plan and, by incorporating the distributed information from various grid connectedsensors, the evaluation of the impacts.Other results from the project include a complete study on energy efficiency and smart grids roll-outbusiness case. From the beginning of the pilot in Évora, EDP understood the crucial impact of energyefficiency gains on the value of the project. Considering the critical role that customer engagementplays as a prerequisite to change behaviors and increase energy efficiency, EDP implemented in Évoraa mix of initiatives aimed at raising awareness about the project and creating a special InovCitydynamic. Regarding residential low voltage clients, a very broad study, was developed together withQmetrics, an independent company specialized in market studies. The basis of the study consisted inmonitoring the electricity consumption of customers in Évora and comparing it to a control group in anearby municipality, with similar socioeconomic and climatic conditions. The group under evaluationincluded the low voltage consumers in Évora - about 32.000. These customers started receivingmonthly invoices based on real consumption (instead of estimates), had the possibility to permanentlymonitor their consumption online and were exposed to the general project communication effort inÉvora, which included generic energy efficiency advice.The results in terms of energy efficiency are highly encouraging; in the first year a reduction ofconsumption of 3.9% vs. the control group was observed. Furthermore, this was a statistically

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significant result, with the result falling in the interval of 1.8% to 6% for a 95% confidence interval(2.1% error margin). The data gathered so far also shows that the effect is persistent, at least two yearsafter the project was launched. This result of about 4% increase in energy efficiency provides acomfortable margin when compared with the conservative estimate of 2% used in EDP’s businesscase. Beyond the impact of the project in the general population of Évora, EDP used the pilot to testthe impact of more sophisticated smart grids products and services, using smaller test groups,conducting surveys and focus group sessions to understand customers’ preferences.The business case for inovgrid is based on a set of benefits of the project accruing to severalstakeholders, including: network operators, regulators, electricity users, energy services companies,electricity retailers, distributed generation promoters and vendors, electric vehicle owners and vendorsand, considering the economic and ecological impact, society in general. The deployment in Évoraprovided strong evidence about many of these benefits,

2.3 Conclusion

Results from Évora provide ample support for EDP’s business case for a nationwide rollout.Furthermore, EDP’s results are aligned with those of the Portuguese regulator in concluding that therollout would create value for society. EDP believes that inovgrid project is of utter importance toalign the EDP Group strategy with the European 2020 Energy objectives, because it has an holisticapproach to the different involved aspects and plays a central role acting as an integrated platform,which can leverage the development of new business models, that will allow to reduce the CO2emissions, inject more renewables in the grid and promote energy efficiency, thus giving a majorcontribution to meet the European Energy targets.

3 Synergies for a European Smart Grid perspectiveBoth presented projects have shown the feasibility of similar and different approaches for Smart Gridpurposes.It is consensus among the projects, that an increased grid observability, mainly at secondarysubstations and LV level will be the key for improving the grid capability in coping with highpenetration of renewables especially in terms of optimized grid utilization and selective, target-oriented invests in grid enhancement. As a second step new services and operation processes need tobe leveraged in order make DSOs more efficient. The increase of the DER integration capacity atlowest possible cost is the major focus for new tools. In German rural grids integration of DER ismostly limited by the voltage bandwidth while there are still current reserves left. Therefore voltageregulation is the most established smart grid tool in Germany. The inovgrid project addresses alsovoltage control but not as a main focus. In terms of secondary substation automation similarapproaches can be found in both projects. The RiesLing RTU-platform and the inovgrid DTC aretargeting to integrate all measuring and control functions in one universal module for different usecases like monitoring, fault detection for increased reliability, power quality and voltage control.Besides some specific concepts functionalities are comparable and new components are introduced.Being open for future advanced applications is one core feature in both cases.Benefitting from smart meters is one focus of the inovgrid project, but was less focused in theRiesLing project. Common result is, that, once installed, smart meters can create benefits for energyefficiency and the measured data can successfully be used for new applications in grid operation likecoordinated voltage control. Furthermore the inovgrid project has shown, that using the meterssensoring capabilities allows an increased performance of operation. The interaction with consumers issimpler and more cost effective. Smart meters enable the DSOs to act proactively on LV gridproblems and anticipate solutions.Both projects have developed the confidence, that a predictive grid operation can be a core tool fortodays and future grid with high share of renewables in order to ensure a secure grid operation.Congestions and critical grid areas can be identified in advance and management efficiently.Furthermore load and distributed generation forecasts as well as state estimation for MV and LV gridwill be the base tools for more complex functionalities, like coordinated voltage control or virtual

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power plants, which include several DER connected to the DSO grid. Open question is still the marketdesign to ensure the unbundling.The RiesLing and inovgrid projects agree, that communication is a key enabler for smart gridapplications. Different approaches have been chosen. On the one hand communication as anoutsourced service from a provider, who guarantees a certain level of availability independently of thephysical realization, on the other hand the operation of an own communication infrastructure, e.g.mainly based on PLC. The outsourcing can provide a ‘buy and forget’ package, which may beattractive especially for smaller DSOs, who do not want to build up the required resources andknowledge. The own infrastructure allows a better control on the communication and the orientation tothe respective use case and can enable new business cases and services for the DSO. At the end noneof the projects can give the answer, which is the best approach, since this decision is depending ondifferent costs, benefits and frame conditions.Despite some national peculiarities both projects had similar major findings which can serve as basisfor common European solutions.

BIBLIOGRAPHY

[1] Backes, J. et al.: The RiesLing project – pilot project for innovative hardware and softwaresolutions for smart grid requirements, CIRED 10.-13.06.2013, Stockholm, 2013

[2] Kämpfer, S., et al.: Das Projekt ‚RiesLing’ – Verteilnetzautomatisierung im Praxistest. VDE-Kongress 05.-06.11.2012, Stuttgart, 2012

[3] Kämpfer, S., et al.: Delikates Gleichgewicht; energy 2.0, 08/2013, pages. 22-26; 2013[4] Backes, J. et al.: Das Pilotprojekt RiesLing - effiziente Automatisierung und innovative

Leitsystemfunktionen für Netze mit hohem Anteil an dezentraler Erzeugung, VDE-Kongress05.-06.11.2012, Stuttgart, 2012