Pid 2620679

Application of Extreme Value Theory for Measuring Risk of Safe Operation of Power System In Adriatic Wind Conditions Ana Horvat #1 , Tomislav Plavšić #2 , Igor Kuzle *3 # System Control Department, HEP-Transmission System Operator, Kupska 4, Zagreb, Croatia 1 [email protected] 2 [email protected] * Faculty of Electrical Engineering and Computing, Unska 3, Zagreb, Croatia 3 [email protected] Abstract — Wind power production in Adriatic wind conditions, especially in Croatian Control Area, is extremely dependent on variable wind conditions and therefore very unpredictable. Accurate wind power forecasting is important to ensure safe power system operation and safe electricity supply. Special attention has been paid to application of extreme value theory in defining, evaluating and measuring risk of wind power forecasting and therefore risk of safe power system planning, operation and control. Keywords : wind power , power syste m, planning , operation, c ontrol, forecasting , risk, extreme value theor y I. I NTRODUCTION Constant increase of electricity production from renewable energy sources, particularly wind power, puts higher demand on successful power system operation and increases risk of safe electricity supply. Wind power production depends on wind speed and wind direction on micro-location of wind power plant (WPP). Meteorological conditions of Adriatic climate can be extremely unpredictable and quite unfavorable for wind power forecasting. Quality of wind power forecasts is defined as a difference between forecasts and realizations. Validity of the forecasts lies in its value, whose accuracy depends on the application of the forecasts. Forecasting error usually represents economic losses to the investor or problems with the balancing to the transmission system operator (TSO). Only way to ensure effective power system control is to produce accurate wind power production forecasts, with minimal prediction errors, and to predict risks of such prognosis. II. ADRIATIC WIND CONDITIONS Adriatic wind conditions, in Croatian control area, are characterized by two specific winds which differ in direction by 90 degrees, popularly called Bora and J ugo. Bora is a dry and cold stormy wind that blows from north-east (NE) and is usually companion of nice and sunny weather. Development of Bora is mostly affected by division of atmospheric pressure over Central Europe, Mediterranean and Adriatic. However, it may appear as local wind. Such a wind arises by cooling air over valleys, which then expands down the mountain. This stormy wind is usually very sudden and fleeting. Bora can blow at any time of the year, but is most common in the winter when it can reach very high wind speeds. In the summer Bora usually blows in time periods from few hours up to two days and in the winter it can blow up to two weeks. Due to the specific shape of Croatian costal area, Bora blows intermittently (in gusts) and often starts quite suddenly. From light wind, Bora can easily become a hurricane. Form of relief defines character, strength and direction of Bora. Depending on the particular location it can blow from N to NE direction. Jugo is a warm and humid wind blowing, from ESE to SSE direction, along the entire Adriatic coast and causing rough seas. Jugo usually accompanies cloudy skies and rainy weather. It is strongest in the southern Adriatic. [1] Fig. 1. Mean hourly wind speed annual distribution (1981-1990) [2] Average wind speed of Jugo is about 4-5 Bf, but often reaches stormy wind speeds. During the summer it can blow

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Pid 2620679