Harald Weber

HIGH QUALITY MODELLING OF HYDRO POWER PLANTS FOR RESTORATION STUDIES

The verification of existing plans for network restoration after blackouts in European electrical energy systems becomes more and more important with the ongoing deregulation process. For this verification high quality computer models of the electrical system are necessary which are able to generate exact results for all possible restoration scenarios. The most important elements of these models are the power plants, which have to be developed with high accuracy. Therefore in this contribution the possible quality of power plant modelling will be shown exemplarily for a francis type and a pelton type hydro power plant, both located in the Swiss Alps. Copyright

Dynamische Netzreduktion zur Modalanalyse von Frequenz- und Leistungspendelungen in ausgedehnten elektrischen Energieübertragungsnetzen

ÜbersichtEs wird ein neues modales Netzanalyse-Verfahren vorgestellt, mit welchem auch die in großen ausgedehnten Energieübertragungsnetzen sporadisch auftretenden langsamen Frequenz-und Leistungspendelungen analysiert werden können. Mit dieser Methode können nicht nur Dämpfungsgrad und Periodendauer einer Netzpendelung bestimmt werden, sondern es können auch jene Kraftwerke ermittelt werden, welche diese Pendelungen im wesentlichen verursachen. Dadurch können gezielt im Bereich dieser Kraftwerke geeignete Stabilisierungsmaßnahmen eingeleitet werden.Um bei der Untersuchung großer Netze den Berechnungsaufwand nicht zu groß werden zu lassen, ist der Modalen Netzanalyse-Methode eine dynamische Netzreduktion vorgeschaltet, welche die Systemordnung des jeweils betrachteten Netzes vorab reduziert, und zwar unter Beibehaltung der dominanten Eigenbewegungen sowie der wesentlichen Zustandsgrößen.ContentsThis paper presents a new procedure of modal power system reduction and analysis.With this procedure the model structure and model order can be reduced dynamically, which is necessary especially in the case of large power systems. By this the degree of damping and the period duration of frequency and power oscillations occuring in interconnected networks can be analyzed.Moreover, those power stations, which are the main cause of these oscillations, can be determined.

Reality oriented simulation models of power plants for restoration studies

Abstract With the deregulation of the European Electricity Network a reduction of the stability of the electrical power system has to be expected. In this context the availability of simulation models of power plants becomes more and more important. These models are necessary for pre-fault-scenarios concerning the estimation of stability limits in normal operation and for post-fault-scenarios concerning the restoration process after blackouts. In this paper, the development of a simulation model of a high pressure hydro power plant in the Swiss Alps will be presented. This power plant is a very important one in the restoration plan of the Swiss grid.

Combining LP and MIP approaches to model the impacts of renewable energy generation on individual thermal power plant operation

A common method of modeling the operation of power plants in competitive electricity markets is mixed integer programing (MIP). Despite the advantages of the method, it requires solving an NP-hard problem. Modeling all of Europe with several thousand power plants thus would take enormous computational power. In order to reduce problem complexity in this large scale system, while still including detailed behavior of individual plants, we develop an approach where MIP is applied only to focus regions that are analyzed in detail combined with a linear programming model (LP) of all other regions. This combination allows for the prediction of impacts of renewable integration all over Europe on individual power plants in Germany. The results indicate that operational hours of thermal power plants will go down significantly, while the number of start-ups will increase. In order to avoid curtailments of renewable power, enhancements in power plant flexibility will be inevitable.

Development of Reality Oriented Simulation Models of Power Plants and Power Systems for Restoration Studies

Abstract With the unbundling, deregulation and liberalisation of the European Interconnected Network a reduction of the security and stability limits of the electrical power system has to be expected. In this context the availability of reality oriented simulation models of power plants and power systems becomes more and more important. These models are necessary both for pre-fault-scenarios concerning the estimation of stability and security limits in normal operation and for post-fault-scenarios concerning the reconstruction process after blackouts. In this paper, the development of reality oriented simulation model of a high pressure hydro power plant in the Swiss Alps will be presented. Today this power plant is a very important one in the reconstruction plan of the Swiss grid. In this contribution all development steps such as modelling, measurements, identification and verification will be depicted explicitly. As result of the investigations it can be shown that even comparatively simple simulation models can guarantee a very good dynamic behaviour compared with the real power plant, and this for the whole working range from zero to full power production.

New Frequency and Power Oscillations in the Enlarged Westeuropean Interconnected Network Reasons and Counter Measures

Abstract After the interconnection of the networks of Poland, the Czech and Slovak Republic and Hungary (CENTREL-System) to the UCPTE-System of West-Europe in Oct. 1995 low damped or even undamped frequency and power oscillations were observed. This oscillations occur up to now if more than ca. 1000 MW active power is exported from the east part to the west part of the system or vice versa. In this paper in principle the relations and chains of causality which can lead to such low damped and dangerous oscillations not only in the UCPTE System are shown.

Impact of Increasing Wind Power Generation on the North-South Inter-Area Oscillation Mode in the European ENTSO-E System

Abstract After the enlargement of the European ENTSO-E power system towards Turkey at the end of 2010, the East-West Inter-Area Oscillation mode in the enlarged the European ENTSO-E power system has been identified in the frequency range of 0.15 Hz (T P = 7s) accompanied by insufficient damping. By the end of 2012, more than 107 GW of wind generation capacity had been installed across Europe, representing about 25% of the peak demand of ENTSO-E power system. In this paper, the impact of large scale wind power generation in the European ENTSO-E system on the North-South Inter-Area Oscillation mode using a detailed dynamic model of the European ENTSO-E system is investigated by gradually replacing the power generated by the synchronous generators in the system either Full Size Converter or Doubly Fed Induction Generator (DFIG) wind turbines. Because the whole system is extremely nonlinear, the analysis method in state space is senseless; therefore the damping behavior of Inter-Area-Oscillations of the whole system was analyzed in detail using the analysis method in time domain. The model was created using DIgSILENT software.

Technical Framework Conditions to Integrate High Intermittent Renewable Energy Feed-in in Germany

The first part of this chapter gives a short overview about the general problems of integration. Therefore a control theory based description of the basic fundamentals of the power system control concepts is given. The second part of the chapter concentrates on the technical framework conditions of conventional power plants to follow the intermittent power feed-in because as long as no large-scale storage systems are available these conventional power plants will be necessary to integrate the renewable energy at least for the next 20 years. Therefore different methods and tools to analyze and simulate the power plant scheduling and to determine the additional life time consumption of highly stressed components of fossil fueled power plants will be presented and illustrated by different scenarios.

INFLUENCE OF WIND ENERGY ON THE POWER STATION PARK AND THE GRID

Abstract The energy supply in Germany was steered by the current demand of the consumers till now. It will change in an adjustment process to an energy supply led by stochastically arising energy offer by wind power stations. The development of the wind energy is pushed at suitable onshore and offshore sites. Up to the year 2030 onshore wind parks are expected with an installed power of approx. 22 GW and offshore wind parks with 26 GW installed power. The planned offshore wind parks with partly more Giga watts of power must be connected to the existing high-voltage transmission system. Another problem is that the wind energy is mostly produced in northern Germany, but is mainly needed in the middle and Southern part of Germany such as the Rhine-Main and Ruhr district. In order to compensate for the fluctuating feeding from the wind power stations backup power plants are needed. They must be able to provide reserve power. A simplified model of the German energy generation and transmission system was used for this investigation. Based on this model a conceivable scenario of the energy supply in Germany in the year 2030 will be discussed in this paper.

Integration of Large-Scale Renewable Energy Sources: Challenges to Thermal Generation in Germany

Abstract In Germany up to 100 GW of intermittent wind and solar power feed-in is expected until 2020. The network load probably will be between 45 GW and 85 GW. Therefore the influence of renewable power production especially onto thermal power generation is investigated by this paper in detail. An adjusted mixed-integer optimization model using the CPLEX solver 11.2 is used to calculate power plant schedules for the thermal generation system with up to 160 single thermal power plants (TPPs). Inter-temporal constraints like minimum up and down times, time depending startup costs, maximum power transients and a detailed allocation of spinning reserve power for primary and secondary control are considered. The load covered by fossil and nuclear power plants is determined considering the currently projected power from offshore wind farms, solar panels, combined heat and power in combination with the German pumped storage power stations (PSPSs) in 2020. The paper includes several scenarios to illustrate the heavy influence and show the results of the used model and time series.