Research On Var/Voit Operation And Reactive Power Planning Of Power Grids With Wind Farms

As the most developed and profitable form of distributed generations at the present hour,wind generation arouses widely concern both in production and science research. Eventhough global economic kept going down in the recent years, wind generation industrymaintained a good development momentum. However, the interconnection of wind farm andpower grid brings problems of power quality, voltage stability, reliability of power supply andpower dispatch decision-making. It’s obvious that the wind farm integration in large scale willhave a great impact on the future grid. So, to rearch on the mechanic of wind farm’s impact ongrid and to develop a voltage control method for grid with wind farm will be of greatsignificance. And in this paper the mechanic of wind farm’s impact on grid, a reactive poweroptimization method and a optimal reactive power planning method for grid with wind farmare put forward, which are funded by the national863program.In the aspect of reactive power planning, the reactive power operation requirements of windfarm in different countries are surveyed firstly. Then the combinated operating senario of theextreme power output scenario (EPOS) of wind farm and the operating mode of power grids(OMPG) with wind farm are proposed. Finally, a optimal reactive power planning method forgrid with wind farm is proposed with combination of EPOS and OMPG. A planning study iscarried out with the2015Zhanjiang Grid of Guangdong province in China, in whichcapacitors and reactor are both considered, and model of which is solved by geneticalgorithm. The study shows that the method proposed can meet the voltage controlrequirement in and before the target year.In the aspect of reactive power and voltage control, because of the fluctuation of windpower which is hard to predict precisely, the voltage control become a problem in grid withwind farm. Also, the uncertaincy of wind power invalidates the operation scenario and voltagecontrol scheme based on the certain power flow. This paper has proposed a reactive poweroptimization model to deal with impact of wind power on voltage security. At first, theprobability of wind farm power output is calculated by combining the distribution of wind andpower output equation of variable speed constant frequency wind turbine. Then theprobability of voltage violation (PVV) is calculated by combining the probability of windfarm power output and the relationship between the power output of wind farm and voltage ofthe grid. At last, a model of reactive power optimization is put forward base on the PVV.Taking a power grid in China as a case, a tradition model of reactive power optimization andthe model proposed in this paper are put into practice and comparison are made between both models. The comparison shows that the model proposed in this paper can not only control thevoltage well, but also lower the probability of voltage violation caused by wind powerfluctuation.