**9. Long-distance transmission**

All countries emphasize on use of clean and alternate energy. As discussed in previous subsections, with the rapid development of RES fresh set of technological requirements pops up on the grid: the location of RE resources distant from load centers, and the power-variability. The characteristics and its control of the electricity grid need a modification to integrate RE [100]. At present many countries lack affordable storage facilities for renewable power. But on a positive note, the excess power is transmitted through the national grid by internal transmission lines. However, connectivity to the national grid should be even or balanced. The large scale intermittency demands to switch in fast-acting conventional reserves on the basis of climatic forecasts on short to long time frame; by setting up grid-scale storage or; by long-distance transmission of RE generation connecting to larger reserves for resources in order to equalize regional and local surplus or shortfall. This section discusses opportunities for renewable energy transmission over a long distance.

Long-distance transmission capacity is necessary to despatch a huge quantity of renewable power a thousand kilometer or more across the country. The construction of transmission tower is given low priority by historically low investment in transmission, community concern over the required right of way in more dense urban areas. Further many long transmission lines are aged and of inadequate capacity. Both remote solar PV and wind energy generation require "Green power Superhighways." HVDC transmission [100] and use of superconductors [100] are costly alternatives as RE itself cost more to the user. HVDC lines offer transient as well as short term voltage stability. Variability of the source can be well managed via an extensive and robust transmission line network. The transmission capacities based on power electronics devices starts to change the grid characteristics and control requirements. The key power electronic technology has a high impact on the power quality because of its fast control and sensitivity to fault and other abnormal conditions of the grid.

So, research is still going on HV superconducting cable for long-distance transmission of RE [101]. Anyway, in the present day of renewable energy, the grid has to serve national character. With more urbanization and industrialization, the reduction of carbon dioxide emission has been essential and requires long-distance delivery of renewable power [102]. Rooftop PV can reduce the need for long-distance transmission, but have a higher cost than wind or concentrating

**131**

integrated grid.

tion and processing.

*Grid-Connected Distributed Wind-Photovoltaic Energy Management: A Review*

capacity and efficiency of long-distance electricity transmission.

emissions of air pollutants, free fuel, and a low gestation period.

additional power quality and voltage/reactive power support.

other DERs, while minimizing the interconnection costs.

unattainable) is the management of this challenge.

emerging in nature and attracts many researchers towards it.

solar power, and with small but considerable esthetic sense. The gradual entry of big wind and solar generation demand huge spending of money in improving the

Many researchers feel till date that there is a growing gap between the grid system and control technologies and power electronics equipment design capability.

Renewable energy is environmentally, socio-ethically and economically sustainable compared with the dominant centralized and non-renewable energy generation systems. However, the techno-economic limitations for ever-growing renewables' share of power generation in the majority of the countries are alike. The RES is not currently cost-competitive with base load coal-fired power, and geographically dispersed. However, it leads over a conventional generation in low

Traditionally, the electric power system is not intended to handle RE generation and storage. But with the rapid growth in the alternate energy sector, the integration of the DE and RES into an electric power grid can be done in many ways along with power quality solution. The power electronic technology plays a significant part in the integration of RES into the electrical grid. They offer exclusive competence over conventional interconnection technologies. They further provide

This chapter describes the various aspects of grid interface for wind energy systems and solar PV systems and some other DERs for electrical system compatibility by reducing the effects on fault, and flexibility in functioning with various

Around 100 research papers in various problems of grid connection have been surveyed but claims in no way to be complete. This particular subject is definitely

It has been discussed that utility RE investments are typically evaluated from regulatory, project finance, and engineering viewpoints. The regulatory evaluation focuses on ensuring utility conformance to RES and that expenses are kept judiciously limited. From a finance perspective, the return on the investment within disjunctive limits of the funding and cash flows for a particular project is evaluated. The technical evaluation determines the engineering and operational safety of the project and the specific technologies deployed. While these approaches are essential for investors, utilities, regulators and ratepayers, they do not scope out the goodness that a RES can convey beyond the boundaries of a given project, such as the usefulness of transmission and storage and the organizational plus point of bringing an

Variability of RES occurs due to the nature of the climate. Thereby the uncertainty in the generation is affecting up to 70% of day time solar capacity due to passing clouds, and 100% of wind capacity on calm days, is much greater than the somewhat expected variations of a few per cent in demand that system operators handle. This has been discussed. It necessitates a more complicated voltage and frequency regulation. The larger the RE entrant, the more complicated (sometimes

Spatial aggregation of RES greatly lessens forecast errors, just as it lessens variability. This may be due to spatial smoothening effect. The forecast error rises further as the time range of the forecast is expanded. Forecasting techniques are improving constantly. But this requires better weather model and better data collec-

*DOI: http://dx.doi.org/10.5772/intechopen.88923*

**10. Conclusion**

solar power, and with small but considerable esthetic sense. The gradual entry of big wind and solar generation demand huge spending of money in improving the capacity and efficiency of long-distance electricity transmission.

Many researchers feel till date that there is a growing gap between the grid system and control technologies and power electronics equipment design capability.
