No abstract

numerous innovations, absence of fuel and fuel-related problems, excellent environmental characteristics and other economic and technical factors result in a permanent decline of PV systems cost and unprecedented growth of photovoltaic markets. Because of this, PV energy production technologies are becoming economically viable even in the northern countries where the annual solar irradiation on the horizontal surface is around 900-1 100 kWh/m 2. new circumstances allow reconsideration of PV systems viability for electricity production in high latitude countries not excepting the Baltic States. This paper provides a review of broad data on global development trends for solar power plants, including countries where solar irradiations are moderate. advantages of PV systems development are justified by taking into account electricity generation costs, external costs and positive impact on climate change mitigation. Further reduction of PV systems cost is reasoned by describing recent innovations that will have a major impact on a new decrease of PV modules prices. The paper also discusses possible ways that could allow minimizing of PV power plants integration costs by reduction of expenditures for power balancing. The provided data reflect that good results in integration costs reduction can be achieved by combining several renewable energy sources like wind, solar and hydro in proper ratios. Finally, the presented data and their analysis indicate that PV power plants could definitely take a certain part in the future electricity generation mix in high latitude countries due to its wide accessibility, economic efficiency, maturity and environmental benefits.

Results of research of the converter control possibilities in the grid-tied renewable energy power plant are presented in this paper. Converter of the power plant consists of the DC chopper and the grid-tied inverter connected in series. Quality of the converter operation depends both on the DC chopper and inverter operation. Two ways of the converter operation control were researched: control of the DC chopper operation and control of the grid-tied inverter operation.Combination of both ways of the converter operation control has to be applied in order to achieve maximum available power production and the best parameters of the converter operation quality, such as maximum available efficiency of the power plant and minimum total harmonic distortion factor.

Results of control possibilities research of the reactive power generated by grid-tied PV power plant are presented in this paper. The innovative grid-connected inverter with the intermediate power storage chain (DC/DC converter) is used for the PV power plant. The converter operates well when DC input voltage generated by the PV source changes in a wide range. Mathematical description for the circuit part between the inverter output and the grid is presented. Detailed researches of PV system were carried out by means of the mathematical simulation. The researches disclosed dependence of the system reactive power on the phase of sinusoidal modulation voltage of the inverter. It is defined that phase of the modulation voltage must be positive and can vary in the range 0÷20 degrees. Researches show that researched PV system can generate the capacitive reactive power for compensation of the inductive reactive power of the grid.Operation mode of the system when the reactive power is equal to zero can be achieved in this system. It is defined that electromagnetic distortion (THD) of the grid has maximal value at the point when the reactive power is equal to zero. Consequently, this feature must be evaluated at the design of the inverter filter.

No abstract