Siemens Energy, Inc. Power Technology Issue 110 Smart Grid Offering Within PSS®SINCAL Ulrike Sachs ® PSS SINCAL Project Manager ulrike.sachs@siemens.com A fast growing sector in energy systems is the so called “Smart Grid” area where a tremendous change in the networks can be seen. The term smart grid has different meanings for different entities, but overall most would agree that smart grid deals with at least these three components: Intelligence in the transmission and distribution networks, such as automation and remote control, intelligent meters, blackout prevention or condition monitoring Smart generation like distributed generation, energy storage, virtual power plants, wind or photovoltaic generation, and decentralized energy management Smart consumption such as meter reading and remote meter controlling, load management, and new tariff models. All this changes the expectation the engineers have for network planning systems such as PSS®SINCAL. PSS®SINCAL offers a full range of analysis methods, from standard load flow to enhanced dynamic simulation for balanced and unbalanced networks, and deals with voltage levels from extra high voltage to low voltage. There are several ways that PSS®SINCAL greatly benefits utilities in modeling analysis and in network operations. Modeling PSS®SINCAL offers the full range of network modeling including the unbalanced network structures and new smart grid network elements (such as wind generation, PV cells, e-cars, etc.) for this first step in network analysis. Figure 1 – Icons of Elements Available in PSS®SINCAL Power Technology January 2012 PSS®SINCAL is versatile – offering a full range of network modeling, including modeling of substation models and heavily meshed networks that can be presented in synchronized schematic and topologic form. These may be based on internet maps in Bing Maps or Cloudmade formats. Figure 2 – Example of PSS®SINCAL Maps Figure 3 - PSS®SINCAL – Network Displayed in Google Earth Page 2 Power Technology January 2012 Figure 4 - PSS®SINCAL Networks and Results can be displayed in Google Earth PSS®SINCAL supports the user in modeling all details from transposed systems for long lines in high voltage down to specialized single or two-phase transformer models with specific wye point connections for distribution networks. There is no need to transfer data between different planning tools, as PSS®SINCAL allows the simulation of all necessary tasks within the same model. Of course, the complexity of the element description differs. For instance, for smart grid elements – e.g., PV, batteries, ecars, wind, micro turbines – PSS®SINCAL models new technologies accurately in all simulation methods, such as load flow, short circuit, harmonics, dynamics and protection simulation. Figure 5 - PSS®SINCAL Modules – Electricity Networks Page 3 Power Technology January 2012 Generation and load profiles, and dynamic data, can be associated with each smart grid equipment model for long- and short term dynamic calculations. This also includes single-phase dynamic models for synchronous and asynchronous machines and DC equipment (converter/inverter). Figure 6 - Example of Smart Grid Network Element DC-Equipment Input Data and the Presentation in the Network Including Interactive Diagrams Simulation Requirements After the user has inserted and validated the data in PSS®SINCAL, the next requirement is the algorithms to correctly simulate the networks which include smart grid elements. Due to the smart generation, the distribution networks change from passive to active networks having all the problems of transmission networks, with the even more critical problem of low short circuit power and simply no detailed knowledge of what is going on in the networks. Therefore there is no reduction allowed in technical presentation of the distribution networks. Micro Grids demand even more automation and control, as the link to the grid is not constantly available and the power management has to include load/generation shedding – according to power limits of the generators or the voltage limits in the network based on load/generator priorities. Generation has to control the voltages in the network by regulating the power factor. Islanding of networks has to be supported and capacity transfer between generators up to the power limits has to be supported as well. Analysis Methods In addition to new smart grid models and simulation requirements the analysis methods have to be enhanced as the conclusions from the existing ones are no longer sufficient. During the last 40 years network planning was based on load flow simulation. However, due to the new realities of smart generation and consumption it is no longer reasonable to study one particular load flow for a network, but instead at least the complete day (if not periods of months or years) needs to be evaluated creating a load profile. This load profile showing load for every quarter of an hour enhances the traditional load flow simulation in large load flow simulations. PSS®SINCAL fully supports load profiles. Page 4 Power Technology January 2012 Figure 7 - Network with Load Profiles and Voltage Plot for a Specific Time Step during the Day Load trimming algorithms (also known as feeder load estimation algorithms) have to take into consideration the generation in the distribution networks and the minimum and maximum load situation. To operate the networks in an optimized way algorithms are needed for optimal branching that lead to recommendations for the SCADA systems. Harmonic studies have to take into consideration the voltage disturbances by the DC equipment and the protection simulation has to handle overcurrent and distance protection in the same networks with directional elements and voltage-dependent tripping. PSS®SINCAL meets all these needs. Support of Network Operations In addition to the network planning the network operation planning is a task of increasing importance. This means that information from the grid (smart meter values from consumption and generation, generator data, and distribution equipment status) has to be transferred to PSS®SINCAL to provide a realistic simulation of the existing network. Here PSS®SINCAL offers different options to link to meter data management systems. All of the data is stored in an SQL database, therefore it is possible to pass load/generation profiles together with the switching state of network devices to PSS®SINCAL, for example via SQL or XML or even with Excel. In this case the network model and the load data will be taken from the database while simulating the network. Figure 8 - Architecture of MDM Integration (eMeter) in PSS®SINCAL Page 5 Power Technology January 2012 Due to the fact that the number of elements with profiles is high and profiles can have many measurements, this can lead to very large memory demand. A solution for this is using the Smart Load Flow of PSS®SINCAL. In this case only the static network model will be read from the database while the profiles are linked by COM-servers from SCADA and/or MDM systems on the fly directly during the simulation. Figure 9 - Smart Loadflow Interface to Meter Management System Figure 10 - Embedded Meter Reading in PSS®SINCAL and Results from Smart Load Flow The most advanced level of simulation for smart grids is the real-time evaluation of the network (for distribution networks in general, this means a latency of 15 minutes) offering recommendations to the network operation. This is based on steady-state but also on new stability simulation in low voltage Page 6 Power Technology January 2012 systems. PSS®SINCAL can request a meter data reading on demand. The results of the load flow are stored in the database and can be used to support network operation. PSS®SINCAL can enhance the SCADA system by determining the state of the distribution network as the SCADA system currently does not have insight into these network components. Even for the dynamic (short term) simulation – both transient stability and EMT studies are needed. The challenge here is the large number of components that have to be modeled with dynamic behavior in three-phase and single phase, and the unbalanced network structure that needs special simulation algorithms. This was done with EMT studies in the past, but PSS®SINCAL can now offer a new transient stability method that also works in unbalanced networks. Models can be built using the graphical model builder, or using existing models (for example from Matlab Simulink), if special measures have been taken during the development of the model. Figure 11 - Micro Grid with three Diesel Generators, Unbalanced and Meshed Network and Results from Long Term and Short Term Dynamic Simulation With these advanced features PSS®SINCAL enables engineers to more accurately model new Smart Grid technology and gives them better insight into the distribution system. With this improved understanding they can operate the system in an optimized way. Page 7