Study on impact of grid connection of distributed photovoltaic system on distribution network peak-valley difference considering photovoltaic volatility

In this paper, firstly an IEEE 13 node feeder system simulation model is established in Matlab/simulink. Then, taking into consideration the typical photovoltaic output fluctuation and daily load curve of the distribution network, and with simulation method, the study obtains the value of the system peak-valley difference considering the superposition of fluctuation of load and photovoltaic output. Furthermore, the paper studies the relationship between the peak-valley difference and the photovoltaic access modes, as well as capacity and operating condition, thus drawing the law of influence of connected photovoltaic system on peak-valley difference. The conclusions of the study can provide an operation reference for the determination of photovoltaic-grid- connection scheme and the peak regulation and planning of distribution network with connected photovoltaic system

Health and environmental impacts of pesticide use practices: a case study of farmers in Ekiti State, Nigeria

Commonly used pesticides and handling practices which might expose farmers and their environment to chemical hazards were investigated in the Irepodun/Ifelodun local government area of Ekiti State, Nigeria. Direct field observations and answers to a structured questionnaire from a random sample of 150 farming households showed that commonly used pesticides comprised herbicides (48.3 per cent), fungicides (28.2 per cent) and insecticides (23.5 per cent). Of these, 86.7 per cent are classified as ‘highly’ hazardous by the World Health Organization (WHO) and have been banned or restricted in many developed countries. Nearly all of the farmers (94.7 per cent) had received no formal training in safe pesticide use and mixed different products. Farmers suffered from discomforts ranging from eye irritation (91.3 per cent), skin problems (87.3 per cent), nausea (86.0 per cent), headache (83.3 per cent) and vomiting (58.0 per cent). More than half of the pesticide applicators (61.3 per cent) sprayed pesticides near water bodies. Only a few farmers reported decreasing trends in numbers of beneficial insects (27.3 per cent) and other animals (29.3 per cent). The results showed that the awareness of farmers and authorities needs to be raised regarding the use of protective equipment and correct procedures when handling pesticides and, also, that there should be stricter enforcement of existing pesticide regulation and monitoring policies to minimize the threats that the farmers’ current practices pose to their health and to the environment