Penetration Of Energy Sources Research Articles

A cogeneration scheme with biogas and improvement of frequency stability using inertia based control in AC microgrid

Abstract Currently, penetration of the renewable energy sources (RES) like solar photovoltaic (PV) panels, wind turbine-based plants is increasing in the conventional power grid to combat pollution, global warming, and to enhance energy sustainability. Fast power electronic converters are necessary to extract power from these sources which do not have any inertia. When more renewable sources are connected to the power grid, it reduces the effective system inertia which results in unacceptable grid frequency changes for any transient. This leads to frequent tripping, cascading fault, and instability of the overall system which can create large-scale blackouts. This work is related to the generation of physical inertia through the biogas plant and emulates inertia from the dc-link capacitor to control the rate of change of frequency (RoCoF) under abrupt load change. The stored energy in a biogas plant and dc-link capacitor in an AC microgrid (MG) can support momentary power requirement which improves the transient performance of grid frequency under unavailability of PV power. A storage system can help to compensate for abrupt frequency change during transient but due to its higher cost and relatively lesser lifetime, these systems can’t be relied upon in the long run. The proposed scheme of cogeneration and frequency control can provide better performance which is simulated in MATLAB 2013 (b). The control system is implemented in hardware using NI-cRiO 9082 in 500 W AC MG which shows 53.57% improvement in RoCoF which complies with the requirement of IEEE/IEC 60255-118-1.

Voltage Regulation of Hydro Standalone 1-Φ Micro Grid using Fuzzy Logic Based Adaptive Sliding Mode Control Algorithm

This paper presents an adaptive sliding mode control (ASMC) of an improved power quality standalone single phase microgrid system. The proposed microgrid system integrates a governor-less micro-hydro turbine driven single- phase two winding self-excited induction generator (SEIG) with a wind driven permanent magnet brushless DC (PMBLDC) generator, solar photo-voltaic (PV) array and a battery energy storage system (BESS). These renewable energy sources are integrated using only one single-phase voltage source converter (VSC). The ASMC based control algorithm is used to estimate the reference source current which controls the single-phase VSC and regulates the voltage and frequency of the microgrid in addition to harmonics current mitigation. The proposed ASMC estimates the reference real and reactive powers of the system, which is adaptive to the fluctuating loads. The sliding mode control is used to estimate the reference real power of the system to maintain the energy balance among wind, micro-hydro, solar PV power and BESS, which controls the frequency of standalone microgrid. The proposed microgrid is implemented in real time using a DSP (Digital Signal Processor) controller. Test results of proposed microgrid shows that the grid voltage and frequency are maintained constant while the system is following a sudden change in loads and under intermittent penetration of wind and solar energy sources.

Hybrid Intelligent Technique SFLA-PSO for Control and Intellectual Process of Power System with Huge Penetration of Non Conventional Energy Sources

Due to the pressure of decreasing the carbon emission and inadequate sources of fossil fuels being a major reason, Renewable Energy is being incorporated rapidly throughout the globe. Smart grids have a substantial prospective towards tapping the non-conventional energy sources in their grid-connected mode or stand-alone mode [2]. Such limited systems across the sectarian domains of distributed generation systems despite the fact of tapping non-conventional energy sources, stay expected to be the advanced networks which may assist in transmuting the power and energy segment through not only delivering energy to distant and isolated communities, but also through better safekeeping and dependability of electrical energy resource in the urban zones [2][3]. Predominantly, due to a very large or bulk dispersion of non-conventional energy, the system units are expected to practice substantial encounters in sheltered and steady state process, very prominently on advanced stages of inconstant and spasmodic non-conventional sources (solar and wind). This paper is aimed to investigate the influence of the distributed generation like Wind and PV on the power system due to the large diffusion of non-conventional sources.

Support mechanisms for renewable energies: their respective strengths and weaknesses. A comparison with the common agricultural policy

A debate is now underway in Europe to decide whether or not the present system for promoting the penetration of renewable energy sources, in particular wind and solar (photovoltaic) energy, should be maintained in the energy balance. This system, based on feed-in tariffs, is increasingly contested because of the undesirable effects which have been observed. Other incentive schemes are possible and the aim of this article is to draw up a balance sheet of the advantages and disadvantages of the main mechanisms likely to assist the penetration of these renewable energy sources.

Fault level prediction for distribution network using fuzzy logic identifier

With the increasing penetration of the renewable power energy sources, the potential fault current of the distribution power systems changes more frequently as the connection structure of the distribution power system varies from time to time. Traditionally, the fault level can be estimated through short circuit analysis which is time consuming and sometimes difficult as it needs to know the parameters of the transmission line and transformers as well as the structure of the power system. In this paper, an online-used fault level prediction method is proposed via monitoring the phasor value of the local positive-sequence voltage and current. The ratio of the voltage change and current change are used to distinguish the natural deviation of the load from the switching operations or disturbances on the grid side. Several continuous changes of the voltage and current caused by load fluctuations are recorded and used to parameterize the equivalent circuit of the power system and to estimate the fault current level. A fuzzy logic identifier is used for adaptively selecting and recording the satisfactory changes by defining an index of confidence level. The implementation of the proposed scheme is demonstrated in a relay after introducing a low-voltage blocking function. A typical distribution power system with renewable generators is established in PSCAD/EMTDC and is used to verify the effectiveness and accuracy of the proposed method under various load changing conditions.

Commodity Price Cycles: Explained by an Expert

Economist’s Corner Oil and natural gas are the lifeblood of modern economies. Together, they account for close to 60% of global commercial energy consumption. Even in future scenarios with a high penetration of alternative energy sources or technologies, oil and gas are expected to maintain a share of about 50% by the middle of this century; more business-as-usual scenarios forecast a share of 60% or more. The transportation sector depends on oil products such as gasoline, diesel, bunker fuel, and jet fuel almost exclusively. The ability to travel and ship goods are the key ingredients for a successful economy; the lack of transportation infrastructure or its low quality has often been a major roadblock for emerging economies to attract investment. It will be difficult and time-consuming to switch millions of vehicles on land, sea, and air to alternative fuels. None of the alternatives, including biofuels, electric cars, and fuels derived from natural gas, appears to be ready to replace oil products in necessary scale although they are certainly making progress. What is the Interplay Between Oil, Natural Gas, and Alternatives? Natural gas is an important feedstock in many industrial processes such as methanol or fertilizer plants, but the growth in gas use has come primarily from the electric power sector, where it has been replacing oil and other fuels (primarily coal) in many countries, in addition to meeting new demand growth. In some markets, more than half of the electricity is generated in gas-fired power plants. The share of natural gas in power generation is expected to increase in most countries as countries try to lower their emissions and as more gas resources are proven and developed across the globe.

The Proof Is in the Putting: Large-Scale Demonstrations of Renewables Integration Showcase Real-World Solutions

The safe and reliable integration of the levels of renewable energy source (RES) penetration expected in the European Union (EU) by 2020 requires the implementation of new technologies to demonstrate the effectiveness of new practices for managing the system and the assessment of the economic impact and replicability potential of the proposed solutions.

Expanding interconnection capacity to integrate intermittent generation in the Iberian Peninsula

Increasing penetration of intermittent energy sources in power systems has been requiring higher operational flexibility and cross-border transmission capacity. Intermittent generation, especially wind and solar power, has grown significantly in the Iberian Peninsula during the last decade and it will keep growing in the next year. Owing to limited interconnection capacity with the French and the Moroccan power systems, generation intermittency has been dealt with mostly within Spain and Portugal, helped by a flexible generation mix. Despite the relatively high flexibility of the Iberian system, in some situations, renewable generation output had to be curtailed. In general, renewable energy curtailment is an emergency action taken in case of network constraints or in case of generation surplus at single node. This emergency action is expected to be more common in the near future if no additional operating measures are taken. This study focuses on the expansion of interconnection capacity that would be required in order to integrate intermittent generation surplus in the Iberian Peninsula in the period 2020-2050. For this purpose, the trade-off between transmission investment costs and the costs of renewable energy curtailment is analysed. Results for different intermittent generation levels and price scenarios are presented and discussed.

Integrating renewable energy sources in the Portuguese power system

The integration of large amounts of renewable energy is an important challenge for the future management of electric systems, since it affects the operation of the electric power system and the design of the transmission and distribution network infrastructure. This is specially due to the connection requirements of the renewable energy technologies, to the extension and adjustment of the grid infrastructure and to the identification of new solutions for operational reserve, in order to maintain the overall system flexibility and security.In this paper, the impact of high penetration of intermittent energy sources, expected in long term in the Portuguese Power System, is analysed and the operational reserve requirements to accomplish a reliable and reasonable electrical energy supply are identified. It was concluded that pumped storage power plants, special power plants with regulating capabilities, will have an important task to provide the operational reserve requirements of the Portuguese Power System. This technology assumes a fundamental role not only to ensure the adequate levels of security of supply but also to allow the maximum exploitation of the installed capacity in renewable energy sources.

Effects of wind energy supplied by independent power producers on the generation dispatch of electric power utilities

Integration of wind power plants into the existing isolated system presents challenges to power system operators. The problem is further complicated to the generation dispatch imposed by the presence of wind turbine generators (WTGs), owned by independent power producers (IPP) with a large penetration of dispatchable wind energy sources. An evolutionary simulated annealing (ESA) algorithm combined with the direct search method (DSM) is developed in this paper for the solution of wind-thermal coordination dispatch (WTCD) problem without restrictions on the shape of cost functions. The proposed hybrid algorithm can be used to maximize the contribution of non-utility wind farms to reducing the cost of thermal dispatch while maintaining an adequate level of supply reliability. The developed WTCD software is also a useful tool for the evaluation of avoided generation cost (AGC) due to purchase of IPP wind energy by the utility. Numerical experiments are included to understand the wind generator output variations in system operating cost analysis and to assess the impact and economic benefits of the installation of non-utility wind farms.

Structural comparison of the models in EMF 12

This paper analyses the structures of the energy and economic models represented in the recently completed Energy Modeling Forum (EMF) study, EMF 12: Economic Impacts of Policies to Reduce Energy-Sector Carbon Dioxide Emissions. The 14 models in the study are heterogeneous, which has a number of advantages. Chief among these is the greater number of insights obtainable by comparing the models' results in and across global warming policy scenarios. To fully appreciate the results, however, it is necessary to understand how a model's structure affects its output. The disadvantage of a diverse set of models is that it complicates structure comparison, and thereby the interpretation of results. The relevant model characteristics fall into three broad areas of comparison. The first is the model type, including market representation. Despite the many differences among the models, five distinct classes of market representations are seen within which models have great similarity. This simplifies understanding the remaining areas of comparison: energy demand and supply modelling. The foci here are the representation of capital stock dynamics and market penetration of carbon free energy sources respectively.

Outlook for New Energy Sources

Examination of the constraints to market penetration of new energy sources indicates that, for all new sources combined, there will be a minimal market share for possibly two decades -Thereafter, however, the new sources' market share will increase rapidly, but they still will not effectively combat rising prices, OPEC, or regulation and control of oil and gas prices. Introduction Energy sources that are either new or potential alternatives or supplements to sources now in use are finally receiving some attention, publicity, and research and development funds. Some energy projections anticipate rather fantastic market penetration by a few of these new sources in a relatively short time, perhaps even a decade. The projections for conventional energy sources range from -20 percent for 1985 to -50 percent for 1995. But the range for new sources is in thousands of percent. Some evaluations of the short-term potential of percent. Some evaluations of the short-term potential of new sources are so optimistic that conventional sources would be threatened; other evaluations have led to the conclusion that there will be little, if any, net energy derived from most of these new sources - solar, geothermal, tidal, wind, hydrogen, and fusion. The issue is not a small one. Financing of conventional sources is already overextended. Also, our technological conceit could be blinding us to impending disaster for the world - the cause would not be too much energy from nuclear warfare, but too little energy that can be harnessed economically. The uncertainty surrounding these new sources is very high. The outlook for all the new sources combined indicates a minimal market share for the next decade and possibly for two decades, but a rapidly increasing share thereafter that will rise to 25 to 50 percent of our energy supply in 50 years. However, we percent of our energy supply in 50 years. However, we write a new report on the energy outlook every 3 to 4 months, and regardless of the statements made here, I would not hesitate to revise these conclusions in the light of new evidence. Some Characteristics of the Item, Sources It is difficult to discuss the characteristics of all the new sources at once, but there are, some fairly common characteristics. In general, they do not offer much promise of low cost and, in fact, they tend to be promise of low cost and, in fact, they tend to be highcost sources of energy even compared with the present price of oil. Geothermal sources may be the exception, price of oil. Geothermal sources may be the exception, certainly if more Geyserville-type resources can be discovered. However, the steam contracts I have examined peg their price to that of oil, so unless there is enough peg their price to that of oil, so unless there is enough developed to create surplus oil and, thereby, force down prices, geothermal energy should not be counted on to prices, geothermal energy should not be counted on to alter the trend in energy prices. Another general cost characteristic is high initial cost, which always tends to work against market acceptance. In many studies over the past 20 years of markets for new materials and equipment for housing or for construction in general, we have always found that higher initial cost placed two strikes against the new source. A lower total cost in use over the life of the item, if it could be clearly and conclusively demonstrated, might give the item a chance for some share of the market; but such a demonstration is extremely difficult, if not impossible, for something new. JPT P. 21