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Abstract: The typical electrical distribution system shows a passive characteristic in relation to power flows (i.e. unidirectional power flows from substation to loads along the feeder). However, with the inclusion of solar photovoltaic (PV) generators along the feeder, this behavior is changed, and characteristics related to power quality, such as voltage level and total harmonic distortion (THD), may be affected. This paper presents the analysis of power quality in a feeder of the urban grid in the city of the Florianopolis, Brazil, with the integration of grid-connected PV systems as distributed generation. The analysis of power quality is based on real measurements of THD on an existing 12kWp PV pilot plant installed in the urban environment, and power flow simulations of a hypothetical PV system of 4.2MWp distributed in the same area, using the ANAREDE software. The power flow simulations allowed assessing the voltage level, the direction of power flow and loading of the distribution lines. The introduction of limited amounts of PV generation as distributed generation in the urban environment was found to be beneficial in several aspects: better voltage profile; power loss reduction and improvement in total harmonic distortion of the voltage (THDv). Furthermore, photovoltaics as a distributed generation source can also postpone feeder capacity upgrading investments. [Copyright &y& Elsevier]

In an urban environment, dual vertical axis wind turbines (VAWTs) are expected to demonstrate more advantage than horizontal axis wind turbine. For VAWT, solidity is one of the most important characteristics, while it has not been well studied. In this study, to investigate the effect of rotor solidity and other characteristics on the power output of counter-rotating dual VAWTs at different rotor centre spacings in a low turbulence intensity condition, twelve wind tunnel experiments for dual VAWTs and six wind tunnel experiments for an isolated VAWT were conducted. The results show that the effect of the dual VAWTs configuration on the VAWT power output is small compared with isolated VAWT under low wind speeds in an urban environment, but the effect exhibits a slight improvement with an increase in rotor solidity. As rotor solidity decreases, the sensitivity of the effect on rotor centre spacing increases. The effect of skewed flow on the power output of dual VAWTs are also well discussed. Furthermore, dual-VAWT systems are studied under real urban environment of a number of major cities such as Guangzhou, London, and Copenhagen. Potentials in different heights are compared with different configurations based on the city planning of those major cities. • An experimental test on various dual-rotor system was conducted in a wind tunnel. • The relationship between solidity and the dual rotor system is analyzed. • The performance of the dual rotor system under skewed flow is discussed. • The potential of dual rotor system on building are studied in various major cities. [ABSTRACT FROM AUTHOR]