7. Internationale Energiewirtschaftstagung an der TU Wien IEWT 2011

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2 An overview and comparison of current situation and future scenarios to integrate DSM in the participating countries of the IEA Implementing Agreement on Demand Side Management Task XVII: Integration of DSM, DG, RES and ES Matthias Stifter 1, Wolfgang Prüggler 2, Seppo Kärkkäinen 3 1 AIT Austrian Institute of Technology 1210 Wien, Giefinggasse 2, T +43(0) , matthias.stifter@ait.ac.at, 2 Vienna University of Technology Energy Economics Group (EEG), 1040 Wien, Gusshausstrasse 25-29/E370, prueggler@eeg.tuwien.ac.at, 3 Elektraflex, Finland, seppo.karkkainen@elektraflex.com, Abstract: The objective of IEA-DSM Task XVII is to evaluate the quantitative and country specific effects of DER technologies at customer premises on the power system and the involved stakeholders. Starting from the current situation of the technology penetration, future scenarios of penetration and respective DSM/DR potential will be estimated and costs and benefits quantified. This paper reflects the current status of the task and discusses the findings so far provided by the analysis and comparison of the country specific experts reports. Three technologies for integration with DSM are evaluated: Heat Pumps (HP), Smart Meters (SM) and Electric Vehicles (EV). As an example the estimation of DR potential for future penetration scenarios of HPs in Austria is presented in detail. Keywords: Demand Side Management, IEA, Heat pumps, Electric Vehicles, Smart Meters 1 Introduction Within the Implementing Agreement Demand Side Management of the International Energy Agency, the Task XVII deals with the Integration of Demand Side Management (DSM), Distributed Generation (DG), Renewable Energy Sources (RES) and Energy Storages (ES). The current phase of the task focuses on the assessment of the effects of the penetration of emerging DER technologies of different stakeholders and to the whole electricity system in participating countries (Figure 1). Currently Finland, France, Netherlands, Spain, Austria are active and others like USA, South Korea, Norway or Australia have contributed in the first phase or contributing to the ongoing research activities. Seite 1 von 15

3 The IEA Task XVII is now almost in midterm. Currently the penetration of the technologies heat pumps, electric vehicle, smart meter, µchp and energy storages and the effect on the power system are analysed. In this paper an overview of the technologies and their penetration of the participating countries which have already contributed their findings are compared to the Austrian situation. The emerging DER technologies discussed are: electric vehicles (EV), heat pumps (HP) and smart meters (SM).. A comprehensive analysis and report of the effects respective cost and benefits will be finished at the end of the task in spring Drivers for integrating DER with DR Drivers are: Different peak loads of different countries: Seasonal differences between winter and summer peaks (or none) KlimAdapt [2]; and intra-day differences (e.g. Spain some 12GW). The integration and curtailment of renewables is also a main driver (in Spain currently to GWh per year). Interfaces of Demand Response Resources Beside the interconnection of the appliances and devices to the electric power system, a communication interface is necessary to control and manage the demand resource. Different standards exist and are used to access the resources. There is no single communication protocol or data model used for the existing demand response mechanism. Harmonization activities are underway but many different approaches are possible. It is easier to have independency of the communication protocol but the data model is in most cases not compatible. Model mappings or interoperability is not possible without loss of information and irreversibility. 2 Methodology and Data In the first phase of the task, information about integration of DSM with DER has been collected from participating countries and other IEA agreements (IEA Wind, IEA PVPS, IEA ENARD). The information has been analysed and status and existing gaps have been identified and synthesized in a state-of-the art report, to define the detailed needs for further work. This report is based on a comprehensive directory of over 50 case studies and demonstration projects together with the country descriptions and represents a summary status of integration of the various fields of the electricity system, like electricity generation, electricity demand, communication, control and monitoring, integration analysis and regulation, policy and business [5,6]. In the second phase the penetration of DER technologies in the participation countries at customer s premises, by name HP, EVs, PV, µchp, SM and energy storages (ES), are assessed. An essential part is the discussion of future scenarios for 2020 and above. In parallel the stakeholders and their involvement are investigated. The current and possible future effect of the technology penetration together with the stakeholder s involvement on the power system is the objective of this task. Seite 2 von 15

4 Figure 1 illustrates this approach: 1. Analyse the status quo of DER penetration at customer s premises 2. Derive future penetration scenarios for 2020 and Estimate the DSM/DR potential based on future scenarios 4. Analyse the impact of future penetration scenarios and the benefits of DSM/DR. 5. Estimate of costs which are necessary to facilitate DSM/DR potentials 6. Evaluate the effects on the involved stakeholders. The methodology used is based on the collation and comparison of the country experts reports, following semi structured questionnaires and analysis of the data. The subsequent synthesis of similarities and differences result in the overview comparison for the investigated technologies. Figure 1: Approach of Task XVII second phase. Data The figures and numbers are based on data sources provided from the corresponding country expert s reports of the specific DER technology. Country reports and questionnaires will be published together with the findings at the end of the task. Estimation on future potentials of demand response for HP in Austria have been based on the scenarios developed in Wärme und Kälte aus Erneuerbaren in 2030 [3] and the statistical data from Innovative Energietechnologien in Österreich Marktentwicklung 2009 [4]. Seite 3 von 15

5 3 Heatpumps (HP) 3.1 Country Situation Austria The current Situation shows that the majority of HP installed are below 20kW thermal power. Approximately factor 10 less the next power class of 20 to 80kW and factor 100 less the above 80kW power class (Table 1). Table 1: number of annual installed HP per power class in Austria [1] HP power classification [%] [%] < 20kW % % 20kW-80kW % 991 8% > 80 kw 127 1% 85 1% Total % % Electric Energy Demand Scenarios for 2030 From the data in Table 2 the number of installed HP and the total potential of DR per HP power class can be estimated (Table 3), assuming that the different power classes have a similar distributed share of the total number of installed HP. Table 2: Mean and total thermal and electrical power of installed HP in Austria [1] Use water HP Heating HP Air condition HP Sum Thermal Power (mean) [kwth / HP a] 2,75 10,8 2,67 Thermal Power (total) [MWth] Electrical power (mean / HP) [kwel/ HP a] Electrical power (total) [MWel] Table 3: Status quo for electrical power consumption of HP in Austria and scenarios according to [3]. HP power classification Percentage on the total share [%] 2009 [MWel] Status quo 2020 [MWel] Baseline scenario 2020 [MWel] Accelerated scenario 2030 [MWel] Base scenario 2030 [MWel] Accelerated scenario Installed HP < 20kW 90% kW-80kW 9% > 80 kw 1% Total 100% The share on existing building types provided in [3] makes the share of HP classes plausible. For instance small residential building (single and double family households) have over 90% share on building space. The status quo of the electrical energy demand, heating and use water heat pumps together are taken from [1]. Seite 4 von 15

6 Practical potential of DR for HPs: In this estimation it is assumed, that the relative share of power classes stay the same; in future scenarios the behavior of scaling will be the same between those classes Realistic reduction of DR potentials: Concurrency factor (full load hours) imply that the full potential will not be available. Following estimation has been made according to the full load hour from [1]: A full load hour of 1540h from total 8760h leads to approximately 35-40% availability in the heating period of six month, if it is assumed, that the HP for heating are mainly operating in the cold seasons. Starting with the first 92MW (9MW+83MW in 2030) of the medium and big sized HP, approximately 2000 HPs must be integrated into DR measures. This number result if the total electric power per class is divided by the power class mean value. The practical DR potential would be up to 36,8MW (assuming 40% availability) of estimated 92 MW from the accelerated scenario during winter time. Prerequisites are thermal energy storage or thermal capacity enabling the possibility for a demand shift. Hybrid between cooling and heating HP (reversible HP) could enable more potential especially for winter and summer peaks. Technology trends have this direction. Impact on the electrical power system Standard transformer power rates are between 0,6 to 1MW, therefore the average share on the distribution grid s load would be between 5% and 15%, when a HP of power class 20kW- 80kW and >80kW is connected. According to the absolute number of HPs per power class installed (Table 3) in 2020 a number between and in 2030 at least distribution grids might be affected. A shift-able load of 15% by avoiding peak loads would already have a positive effect on the asset s lifetime or would delay the reinforcement by increasing the safety margin of the transformer. Load flow simulations are needed to analyse these effects in detail. Gradual load control would also improve the facilitation and is seen as important to support possible services for DR Finland The current penetration of heat pumps for heating is about 6% and heating with electricity about 17,9% share of the heating methods by end energy use [16]. From detailed analysis of the load characteristics of the different heating methods in Finland during typical winter day, the load flexibility in the Finnish residential sector has been analysed. Loads are categorized in the four categories (Figure 2) [17]. Easily manageable loads consist mainly of electric heating. Storage electric heating is already controlled by two-time tariff system, and there are considerations for more sophisticated control systems, based for instance on the spot-prices of the electricity. However, while storing electric heating systems have already installed control systems, situation is not the same for the heat pumps. Hence, in order to control heat pumps, the development for the practical load management application to the customer end and modifications in the customer installations are needed, which obviously is a quite burdensome task. Seite 5 von 15

7 Figure 2: Estimated flexibility potential in the residential sector during an average winter week [16,17] Netherlands In the utility building sector heat pumps have found their way in installation system design and configuration. Their use has been awarded in the design performance specification index. Their penetration has reached a % level [16]. In the fields of using DR and storage one project is currently in operation: Hoogkerk is the PowerMatchingCity field test: Software agents coordinate commercial and distribution grid optimization with wind imbalance compensation and valorization of renewables [12]. Simulation studies have been done on the black-start problem in the SmartProofs project [19] that will be followed by a real field test in a hotspot heat pump area. 3.2 Comparison Table 4: Criteria for evaluating integration of HP into DSM measurements Criteria Austria Finland Spain Netherlands Primary usage Control and flexibilty Impact on power system Impact on stakeholders / services Drivers / incentives Use water, Heating system PLC and Interruptable Tariff Penetration for HP low, Currently 333MW electrical Power, Potential for 100MW controllable load in 2030 Energy contracting Lower price tariff, investment incentives 25% of renovation costs; deduction of taxes 1996 GWh total 1 (2007) Between 1 and 3 GWh/h depending on time of day 2 Heating system, cooling Use water and heating in utility (30-40%) and residential hotspots overload on cold days exceed designed connection power - blackouts APX 1h; imbalance market 15min; High tariff customers; Incentives for investment 506GWh per year Electricity demand 333MW Theoretical: MW DSM potential Practical: 92MW/36,8MW permanent available 3 1 Sum of ground source, air source and exhaust air source HP 2 Estimated flexibility potential in the residential sector during winter days (Evens et al. 2010) 3 See Seite 6 von 15

8 4 Smart meter (SM) The regulated functionally of smart meter to support DSM is investigated. For integration of the demand side the functionality of smart meter must support DSM mechanism. SM functional requirements will enable DR at customer premises, it could act as a gateway to communicate and control directly devices. Mandate M/441 Standardisation mandate to CEN, CENELEC and ETSI, M/441 on SM, lists the following main functionalities: Remote reading Two-way communication Support advanced tariffs and payment systems Allow remote disablement Communicate with (and where appropriate directly controlling) individual devices within the building Provide information via web portal / gateway to an in-home / building display This is not seen as a minimum list of SM functionalities and decision on these functionalities is left to the individual member state to determine [7]. 4.1 Country situation Austria It has been estimated that the electricity demand reduced by the introduction of SM will be about 3.5%. Reductions will be due to display of the current demand and the introduction of time-of-use tariffs [8]. Current situation in Austria is that approx SM are installed, and it is planned that 80% of the customers will be equipped in 2020 [19]. In the Austria consultation paper issued from E-Control the following requirements are listed which can enable DSM: Minimum of 4 registers for different tariffs per day (time of use). Communicate with at least 4 external meters - possible use as synergy for energy management systems Interface to external system It is explicit stated, that the SM would not act as a gateway to home automation system to directly control external devices [9] Finland The Task report on Smart Metering [10] lists the requirements for SM in Finland. Differences in functionalities to Austria are: Interface with local automation network or home automation network (eg. ZigBee, Ethernet, etc.) Load management via the meter with a dedicated controlled circuit Seite 7 von 15

9 4.2 Comparison Table 5: Criteria for evaluating SM enabling DSM measurements Criteria Austria Finland France Spain Netherlands Functionalities which enable DSM No, (Interface to display) Yes Yes Yes Yes Penetration scenario 80% (2020) 90% (2020) 100% (2020) 50% (2020) 100% (2020) Impact on power system Reduction of consumption 3,2% Wind is driving Spain to look at DR Wind is a big issue; DNOs will adopt them 5 EV 5.1 Austria Table 6 shows the present situation of hybrid and electric cars [13, Statistic Austria 2010] Table 6: Fleet penetration of hybrid and electric cars ( ) [13, Statistics Austria, 2010] Passenger cars , Hybrid cars Electric cars :The penetration scenarios for passengers EVs in Austria in Table 7 and Figure 3 are taken from [11]. From these scenarios the potential for DR will be estimated for the task report on Electric Vehicles. Table 7: Number of electric vehicles for passengers in Austria [11] Waiting Chasing Steering Figure 3: Share of passenger EVs in Austria [11] Seite 8 von 15

10 Definition of the Scenarios [11]: Waiting Reference scenario and moderate oil price increase Chasing high increasing oil pricing catching up with international developments Steering challenges can be met early enough, measures taken Impact on the power system / distribution network A recent study from Klima & Energiefond has estimated the impact of uncontrolled vs. controlled charging. In case of controlled charging, 2% of total el. consumption at 20% penetration would have no impact from the transmission grid point of view [22]. While detailed study on the rural distribution grid has shown, that the distribution grid is stressed in case not only uncoordinated high power charging at 20% penetration [23]. Studies on the impact on the distribution grid at inner city regions show, that a share of up to 60% doesn t make a problem [24]. Subsidies and fiscal policy In Austria electric cars are excluded from tax on ownership and tax on acquisition (up to 16 %). (Source: Austrian Federal Ministry of Finance) There is one nation wide subsidy program that supports the acquisition of electric vehicles for commercial fleets of up to 10 cars or light-duty vehicles (with curb weight lower than 3.5 t) with 2500 respectively 5000 in the case that renewable electricity is used. The subsidy is financed by the klima aktiv mobil initiative supported by the Austrian federal ministry of environment. [25] There are also subsidies for the acquisition of electric cars in three of the nine federal states: up to 5000 in Lower Austria, 1500 in Styria, 750 in Burgenland. Furthermore, there are subsidies in cities and municipalities [26]. 5.2 Finland The penetration scenario for Finland estimates 25% of all new cars in 2020 are hybrid plug-in vehicles and 10% full electric vehicles. The daily travelling distance in Finland was calculated with 42km in average and 32km for passengers [13]. Impact on the distribution network Results of these studies, similarly as in the nation level studies, reveal that the peak demand would increase, if the charging of the vehicles is uncontrolled, and, again, by employing smart charging, increase in peak demand can be avoided. The results of these studies are illustrated in Figure 4, where the changes in the peak load of a medium voltage feeder in the densely populated area is presented with different charging strategies of the electric vehicles. Relevant input data of the calculations is presented in the figure also [13]. Seite 9 von 15

11 Peak power [MW] EE Direct night-time charging Working-hour and time-off charging Split-level night-time charging Optimised charging City area feeder: - Peak load of the day: 6.6 MW - Minimum load of the day: 4.0 MW - Number of electric cars: Driving distance: 57 km/car,day - Energy consumption: 0.2 kwh/km - Charging energy: 11.5 kwh/car,day à 22.9 MWh/day for all cars - Charging power: 3.6 kw/car - Additional power: MW (depending on charging method) - Charging energy (E) is equal in each charging alternative Figure 4: Peak load of a city area medium voltage feeder with (blue line) and without electric vehicles in four different charging strategies [13,14]. Furthermore, there have been studies about the interface between the plug-in vehicles and power system, including the physical electrical interface and ICT-interface, as well as electricity market models for the billing. The possible principles of these are illustrated in Figure 5. Figure 5: Interface between plug-in vehicles and power system (Rautiainen 2010) Subsidies Purchase tax and an annual tax for passenger vehicles in Finland depend on the CO2- emissions. It is between % from the purchase value; minimum tax is achieved by the CO2-emissions of 60 g/km or less, while maximum tax is for vehicles with the emissions of 360 g/km or more. Similarly, annual tax varies between /a, where the cut-off Seite 10 von 15

12 points are 66 g/km and 400 g/km. Since electric vehicles belong to lowest emission class, they get benefit in the present taxation system. There is an annual fuel-tax for the vehicles, which use other fuels than gasoline or natural gas or biogas. Tax is based on the weight of the car (6.7 snt/d for every 100 kg of mass), and for typical passenger car it is /a. This tax is applied also for electric vehicles, and hence it hinders the economical profitability of the electric vehicle. However, there has been public discussion about the possible development needs in the fuel tax, especially concerning electric vehicles 5.3 Netherlands Currently a field test for controlled charging of EVs is carried out [15]: This project is based on load control and smart charging. The technique which the project depends on is a controlled way of battery charging where the external control signal has direct influence on the charging speed with a response time of seconds. The battery may be installed in a (PH) EV or somewhere stationary. The charging speed of an EV can be tuned externally somewhere between 0% and 100% of the maximum capacity of the charger. Anywhere, anytime whenever the car is connected to the grid. Dutch initiative energy sector / all the independent DSO s and most utilities investigated market models which facilitates smart charging of EV s. Figure 6 shows the measured result on the transformer load from the field test. Figure 6: Impact of the local charge controller on the transformer load [15] 5.4 Spain In the Spanish system 6.5 M full EV could be charged without any additional investment in generation and transmission, if the cars would be charged off-peak hours. The current renewable curtailment in Spain is about to 2.000GWh, which would be 0,32% to 0,71% of the total electric demand in This would be enough for to Seite 11 von 15

13 electric vehicles. According to the penetration scenario, 1.7M EV could reduce of 25% energy curtailment in 2020, by consuming MW of demand in off-peak hours. The penetration scenario for EV in Spain is shown in Figure 7. Figure 7: Number of electric vehicles in Spain [20] It is assumed, that EV could participate in ancillary services and energy market, possible through an Aggregator: Participation in Ancillary services (regulation with response within 5 min, contingency reserves with response within 10 min) Participation in Energy markets (scheduled in day-ahead markets) The strategy establishes an objective of EV in Spain for Four different scopes with a total of nine programs have been formulated in order to fulfill these objectives. Three working groups have been established to plan the EV development: Promotion and demand, Industrialization and R+D, Infrastructure and DSM. For this reason, the law has been already modified: The new subject Charge Manager and the new activity Energy charging services have been established [21]. 5.5 Country comparison Table 8: Criteria for evaluating integration of EV into DSM measurements Criteria Austria Finland France Spain Netherlands Control and flexibility Charging stations Impact on power system Impact on stakeholders / services Wireless is discussed (AMP) IEC (to be likely) > 30 kw: solely DC charging (CHadeMO- Standard18 with a YAZAKI- Plug) Uncontrolled vs. controlled charging, 2% of total el. Consumption with 20% penetration, stress of distribution grid in case of high power charging. In urban / city regions a distribution up to 60% doesn t make a problem EV service provider Energy must be provided PLC and GSM are under discussion TCP/IP is recommended IEC (phase 1) at private premises Intelligent Management is needed to integrate renewables and for efficient system operation EV aggregator Charge 16A A A 400 DSR, load control, peak shaving; Impact on power system utilitzation EV aggregator Seite 12 von 15

14 Incentives/Subsidies from renewables, Tax exclusion / incentives Subsidies benefit in the taxation system fuel- tax increases EV costs Manager 6 Conclusion The analysis of the current country status shows major differences of the penetrations of technologies based on country-specific policy, regulations and market situations: Heat pumps (HP): The technologies and penetrations of heat pumps in the various countries are presented. The problems and promising experiences from field test from heat pump control projects are shown. Some findings are: The Dutch country situation shows, that impact of high concentration of HP ( hotspots ) already cause overload and exceed the designed connection power. Estimation of the potential for demand response of HP in Finland is 2 to 3 times higher compared to Austria. This is most likely due the more frequently use of the built in direct electrical peak heating for cold days, which can be observed in Holland as well. The need for gradual control of the HP load in respect to grid impact and intra-building comfort optimization strategies seems to be obligatory to integrate HP into DSM programs. Market beneficiaries operating such service have to consider and support this. Cooling and heating hybrid HP technology (reversible HP) could enable more potential especially for winter and summer peaks. Technology trend has this direction. Smart meters (SM): The need for recommended and regulated functionality of smart meters in relation to DR functionalities in the participating countries and country specific requirements is discussed in relation to the recommendation of the EU DG-TREN experts group on smart meters (EG 1) and the EU commission mandate 441. Electric vehicles (EV): Various approaches for incentives for electric vehicles exist in Finland, the Netherlands and Norway which are also regionally different as opposed to Austria. The drivers for EV, different tariff models and their impact on the grid together with control mechanisms are introduced - demonstration projects in the Netherlands and Spain are discussed. Spain is among the first country to already have modified the law for the electric sector and introduced the Charge Manager as a new subject and the Energy charging service as a new activity. 7 Outlook The IEA Task XVII is now in midterm. Focus in the second phase of the task will be on the DR potential of microchp, PV systems and electric & thermal storages. A comprehensive analysis and report of the effects respective cost and benefits will be finished at the end of the task in spring/summer Seite 13 von 15

15 References [1] Innovative Energietechnologien in Österreich Marktentwicklung 2009, Berichte aus Energie- und Umweltforschung 15/2010, Bundesministerium für Verkehr, Innovation und Technologie, 2010 [2] KlimAdapt, Ableitung von prioritären Maßnahmen zur Adaption des Energiesystems an den Klimawandel, Energie der Zukunft, Endbericht, November 2010 [3] Haas, R.; et. al.; Wärme und Kälte aus Erneuerbaren 2030; TU-Vienna, EEG, für den Dachverband Energie-Klima und WKO, Oktober 2007 [4] Innovative Energietechnologien in Österreich Marktentwicklung 2009, Berichte aus Energie- und Umweltforschung 15/2010, Bundesministerium für Verkehr, Innovation und Technologie, 2010 [5] IEA Implementing Agreement on Demand Side Management, Task XVII: Integration of Demand Side Management, Distributed Generation, Renewable Energy Sources and Energy Storages, State of the art report, Vol 1: Main report, 2009, [6] IEA Implementing Agreement on Demand Side Management, Task XVII: Integration of Demand Side Management, Distributed Generation, Renewable Energy Sources and Energy Storages, State of the art report, Vol 2: Annexes Country Reports and List of Pilots and Case Studies, 2009, [7] Smart Meters Co-Ordination Group; Standardization mandate to CEN, CENELEC and ETSI in the field of measuring instruments for the development of an open architecture for utility meters involving communication protocols enabling interoperability M/441; Final Report, Version 0.7, [8] PwC Österreich, Studie zur Analyse der Kosten-Nutzen einer österreichweiten Einführung von Smart Metering, Juni 2010 [9] E-Control, Leistungskatalog für fernauslesbare Smart Metering-Systeme im Bereich Strom, Öffentliches Konsultationspapier, Juni [10] IEA-DSM Task XVII Report on Smart Metering, 2011(Draft) [11] Visionen 2050, Identifikation von existierenden und möglichen zukünftigen Treibern des Stromverbrauchs und von strukturellen Veränderungen bei der Stromnachfrage in Österreich bis 2050, Executive Summary, 2010 [12] [13] IEA-DSM Task XVII Report on Electric Vehicles, 2011 (Draft) [14] Lassila J., Kaipia T., Haakana J, Partanen J., Järventausta P., Rautiainen A., Marttila M Electric cars challenge or opportunity for the electricity distribution infrastructure? Proceedings of the European conference on Smart Grids and mobility, June 2009, Germany [15] [16] IEA-DSM Task XVII Report on Heat Pumps, 2011 (Draft) Seite 14 von 15

16 [17] Evens, C., Kärkkäinen, S., and Pihala, H Distributed resources at customers premises. Research report VTT [18] [19] E-Control: Flächendeckende Einführung von intelligenter Zählergeneration (Smart Meter) bis 2016 realisierbar,presse Information, März 2009 [20] RED Electricia de Espana, Electric vehicles and intelligent battery applications, IEA- DSM Task XVII Expert Meeting Vienna, 2010 [21] Royal Crown Decree 6/2010, 9 th April, Modification of law 54/1997, 27 th September, of the electric sector [22] PricewaterhouseCoopers, "The impact of electric vehicles on the energy industry", Klima und Energiefonds Austria, 2009 [23] S. Tselepis, E. Lemaire, J. Mertens, P. Norgaard, H. Bindner, P. Mora, E. Kolentini, M. Stifter, R. Bündlinger, B. Bletterie, D. Burnier, T. Degner, W. Heckmann, Grid integration issues for EVs / PHEVs: the DERlab approach, Smart Grids and emobility, 2009 [24] Bolzer, A; Auswirkungen elektrischer Mobilität im Verteilnetz, Thesis, TU-Vienna, 2009 [25] [26] Seite 15 von 15