Abstracts - VGB PowerTech Journal 10/2016
Editorial: The VGB “Hgcap(ture)” initiative
Further reduction in mercury emissions from coal-fired power plants
Dr.-Ing. Oliver Then
The use of fossil fuels in electricity and heat generation, and especially hard coal and lignite, will continue to make an important contri-bution to a safe and competitive energy supply system and to industry in Europe. Also with a view to the technical challenges of the energy transition, conventional power plants continue to be indispensable as a partner of the renewables. [more...]
Energy in transition – Between regulation and market
Günther Horzetzky
Actually, the energy industry is affected in a changing market environment. The expansion of the renewables led to a share of about 30 % of the German electricity production and is always rising. The renewables energy levy has reached a level of 6.35 €Cents per kWh, which is actually a high level. Investments in new power plants are stopped due to low market electricity prices. The market pressure on the utilities is high and their business models have to be scrutinised. The NRW state government supports the magic political triangle of a secure, affordable and environmentally friendly energy supply. Instead of further interventions we have to develop our existing energy system cautiously. Anything else would not meet the requirements for invests in the energy supply and the magic triangle of energy politics.
From base-load to flexible operation – An innovative operation approach for CCGT plants
Christof Fischer, Thomas Zimmerer and Florian Röhr
The commercial terms for conventional power plants have substantially changed in the recent years. The strong increase of preferential feed-in of renewable generation and the resulting overcapacity in power generation is the main reason. Plant closures of older fossil power plants are still exceptional. This article describes realised optimisations to enhance the operational flexibility of a combined cycle power plant with steam extraction for process and district heating purposes. In detail, the technical implementation of a fast start routine and active heating of heat recovery steam generator and steam turbine will be presented as well as its commercial aspects.
Information security in operation and control of electricity generation plants
Kay Tidten
In the context of the “Energiewende” (turnaround in national German energy policy) and increasing digitalisation the existing requirements for security of information systems are rising. These recent debates have lead to numerous increased regulatory requirements in this area. In summer 2015, German Bundestag adopted the “IT-Sicherheitsgesetz” (IT-Security Act), in summer 2016, the European Parliament and the European Council adopted the Directive for the security of network and information systems (EU-NIS-Directive). This article gives an overview over the increased requirements in information security in generation plants in the context of new regulatory requirements in Germany and the European Union.
About design and operation of large-scale virtual power plants
Sleman Saliba and Sebastian Hölemann
The architecture of the control system for a virtual power plant is crucial for success in the challenging energy market environment. Because of the huge variety of business models there is no single solution for a control system, on the contrary, it needs to be tailored around the requirements of the VPP operator. The purpose of this paper is firstly to show the design and modelling of VPPs, secondly to describe current experience in the field, and finally to point to further applications that can be implemented by means of an adaptable platform for the control and optimisation of decentralised power generation units, storage devices and flexible consumers. Based on experience gained in the successful running of one of Europe’s biggest VPPs, it can be seen that demand-oriented operation combined with grid services increases revenues and ensures a high level of renewable energy system integration. In fact, pooling renewable sources in virtual power plants contributes substantially to grid stability.
Development and comparison of a central and decentral coordination approach for virtual energy storages
Leander Grunwald, Sebastian Ruthe and Christian Rehtanz
In urban areas, decentralised generators and loads can be pooled to operate as a virtual energy storage. Therefore, the flexibility of thermal storages (e.g. in CHP units) can be used to increase the storage capacity of the electrical grid in the future. This approach is evaluated in the project “Die Stadt als Speicher”, funded by the Federal Ministry for Economic Affairs and Energy. Various types of objective functions such as spot markets and residual load minimisation are considered in two different model regions. Within the scope of this publication, the central and decentral aggregation concept will be introduced including the state of implementation. Then, both will be compared particularly with regard to non-functional requirements such as robustness, scalability and single point of failure.
Power System Restoration: Interactions between wind energy generators and thermal power plants
Holger Becker, Tobias Hennig, Alev Akbulut, Denis Mende and Lutz Hofmann
Large area electrical system breakdowns (blackouts) cause economic losses and restoration is a major challenge for the transmission system operator. Planning and analysis of restoration strategies is usually performed by the simulation of large electrical systems because experiments can rarely be conducted at the system. These simulations require dynamic mathematical models which represent the functions of all generators being involved. An analysis of historical blackouts and the causes that have brought upon the situation are presented, followed by some potential functions that wind energy generators could provide to system restoration, as well as results of analysis of the interactions between wind energy generators and thermal power plants during the process.
Challenges at grid connection and operation of offshore wind farms
Steffen Schüler and Dirk Matzke
The development of wind energy is already an ongoing progress since over more than 20 years in Germany. Thereby the offshore wind energy is one essential part of the transformation of energy sector. But the responsibility of those power plants to the entire supply system increases with the expansion of their installed power. This means that capacities has to be provided and system services has to be overtaken which are currently performed for the most part by the conventional power plants. First operation experiences demonstrate the current challenges and give an outlook on future possibilities for more sustainable and powerful system concepts to meet all requirements of the constantly increasing requests on the way to an efficient and intelligent energy supply system.
The new control room for the Niederaußem power plant
Hartmut Erler and Uwe Kimmeskamp
Utility company and power plant operator RWE assigned Mauell with the task of designing and constructing a new large-scale central control room for Niederaußem power station. The project involved the following steps: assessment of the initial situation, requirements specification taking into account the technical/ergonomic conditions and the workflow processes, analysis of the spatial conditions. The implementation of the control room design required comprehensive architectural changes. The control room was converted in two phases while the plant was operating.
The new high-flexible Chemiepark Marl power plant
Marl Norbert Hönings
E.ON plans and realises distributed industrial power plants on the basis of contracting schemes, allowing customers to reduce energy costs without own investment from their part. Gas turbine CHP plants are very flexible and offer many possibilities for the operator to adjust optimally to a constantly changing energy market. In the chemical park of Marl, a highly flexible industrial CHP plant was realised in time and in line with the budget and is now successfully in operation. The plant has a power generating capacity of 60 megawatts and a thermal capacity of 100 megawatts. The fuel utilisation rate is 89 per cent, which helps to save approximately 280,000 tons of CO2 annually.
Heat recovery from a fluidised-bed combustion unit
Stefan Seele
Changes in the energy market present a major challenge for the operators of power generation plants. Declining revenues in the power market require more flexible fuel input strategies, which aim at lowering fuel expenses. One method in use at the Pforzheim cogeneration power plant is a circulating fluidised-bed combustion unit fuelled with coal from Germany and Poland. The former ash-transporting screw conveyors cooled by river water, were replaced by so-called vibrating-cooling conveyors, which shift out the impurities from the ash stream in two stages, thereby ensuring pneumatic conveyance. Now, the system is cooled by the return water of the local district heating network system cycle. In doing so, heat is recovered, which also reduces primary fuel consumption. In addition, this creates more flexibility when considering the already limited opportunities available when river water is used for cooling purposes.
Experience in examination of curved last stage blade roots on steam turbines
Chris Ward
There is an increased possibility that final-stage steam turbine blades will fail because blade designs are becoming more complex and operating conditions are becoming more demanding. Because of this increased risk, requests for inspections are increasingly frequent and it is important for turbine owners/operators to understand the scope and limitations of these inspections in order that they can effectively manage the integrity and availability of their turbines. RWE Inspection Management have more than twelve years of experience of inspecting both the final-stage steam turbine blades with complex curved-root fixings and the corresponding rotor slots. These inspections have been undertaken with a variety of inspection methods.
Interlaboratory comparison for SRFs and waste wood for recycling: influences on quality and the comparability of analytical results
Monika Denner and Michael Ghobrial
The first interlaboratory comparison study for SRFs (secondary recovered fuels) and waste wood for recycling (Umweltbundesamt 2014) was carried out on behalf of the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management (BMFLUW) in order to describe the status quo or current quality of the practical implementation according to the requirements of the Austrian Waste Incineration Ordinance (AVV) and the Waste Wood Recycling Ordinance. The proficiency test designed by the Environment Agency Austria, included the development of sampling plans and the preparation and analysis of real samples of commercially available SRFs and waste wood.