Impact of distributed generation grid integration and evaluation of grid code compliance with respect to power system simulations

It is obvious that future's energy structure will stand at a very different point from today. As the need for electric energy has grown and turned into a huge dependency, the quest for different sources has always continued throughout the past until today. As technology has been shaped rapidly according to contemporary requirements, our requirement for electric energy can be obtained from energy sources that have different structures and forms. When the power system structure in the world and Turkey is assessed, it is seen that in parallel with the increase in energy demand, the number of generation units that are connected to the distribution system also increase in addition to the stations that are directly connected to the transmission system. The fact that small and medium sized production stations can be erected and operated in the technical & economic sense, allows that the fossil fuel based and renewable sources of energy, which are located on the existing geography in a sporadic manner, can be used during the production of electric energy. The number of distributed production plants, which are connected to the distribution system and which are especially based on hydraulic and wind energy, is increasing rapidly due to our large geography and high availability of resources. The concepts of reliability and sustainability have drawn attention as the distributed generation plants, which provide benefits to both the producer and the consumer in the environmental and economic sense, have been integrated within the existing power network. Potential problems and operating difficulties that may be introduced by the integration of distributed generation stations should be examined during the designing phase of the system, necessary corrections should be made and plans should be created for a safe operation of the new structure. According Turkey's energy strategy for 2023, the percentage of installed power that is targeted for wind stations until 2023, is considerably high when compared with other sources of energy. In this sense, the effects on the future power system of "RES structures connected to the distribution system", which is new in terms of technology and integration to the system, bears importance. It is necessary that the pertinent stations should be examined in detail and correctly, as they will have great impacts in terms of network reliability and sustainability. As far as the integrations of the distributed generations are concerned, one should make a thorough evaluation of the voltage regulation, voltage flicker, harmonic distortion, isolation (island mode operation) risk, changes in the grounding structure of the enterprise, increase in the level of short-circuit current, overcurrent protection coordination, reactive power capacity limits, their behaviors during/after breakdowns, their reliability and their reactions against the changes in network voltage/frequency. Such effects should not be considered solely in terms of structure & capacity of the DG Unit, but also in terms of the connection point, the dynamic characteristics of generators, the variables/characteristics of the distribution system and the consumers connected to the distribution system; and an evaluation should thus be made into the system's entirety. Under today's conditions, problems covering the category of energy quality can be solved by using filters and a correct selection of convertor structures, and these can be examined on a measurement basis. Analyses on load flow and short-circuit, which are necessary for dimensioning equipment, can be performed easily and basic impacts under this subject can be analyzed. As there exists many impacts like the effects of distributed production plants on the voltage regulation, the reactive power capacities and dynamic behaviors of the wind power plants, where all variables should be assessed collectively, it has become even more important to perform these advanced-level analyses and to take corrective actions upon examining their results. This study has evaluated the effects of the distributed generation plants on the network integration and touched upon potential problems that can owe to integration. It has touched upon the analyses needed with consideration of the pertinent standards, regulations and technical criteria that can enable the prevention of potential problems facing energy quality and sustainability. Specific studies have been performed for the analyses of advanced-level power systems at plants with different structures, network compatibility has been interpreted, the results obtained have been examined thoroughly and necessary recommendations have been given. For obtaining high productivity from distributed generation stations and mitigate distorting effects, such distributed generation units should be assessed and planned as a whole with the development of the distribution network, the compatibility of its existent and future structure, and the planning for protection and operation. In parallel with the changes in the power system structure, the pertinent regulations and technical requirements also change and improve. For this reason, the changes in the pertinent regulations and additional demands should be followed-up closely. It is important to perform preliminary examination and analyses for circumventing integration problems however, there are uncertainties covering the manner of such analyses and the points that require attention. It will be possible to minimize distorting effects through standard approaches and by using certain methodologies. Potential problems will be minimized and future's new energy structure that is of quality, secure & environmental friendly will emerge when the subjects of system structure, the generation-consumption balance in the region, voltage increase/decrease, capacities/controlling of the reactive power and the compatibility of the protection coordination system are assessed in terms of the pertinent distribution system with a wholistic approach instead of concentrating on a particular part of the power system and when due measures are also taken.