Grid Codes in Study
This chapter presents a detailed study on the international rules and regulations imposed by TSOs/regulators on large RPPs. Primarily, the codes corresponding to the countries with significant RPP penetration are considered. According to [4], the top countries for nonhydro renewable power capacity at the end of 2012 were China, United States, and Germany, followed by Spain, Italy, and India. At the end of 2012, the EU had the maximum amount of nonhydro renewable-based generation. Most of that capacity came from solar PV and wind and it was recorded as approximately 44 % of the global total. Along with codes of the mentioned countries, parts of the UK, Canadian, and Australian grid codes have also been taken into account.
Design of grid rules and their applications are dictated by the size of the RPP unit. In order to increase utility confidence with RPPs at distribution levels, industry organizations such as IEEE and Underwriters Laboratories (UL) began to develop standards that enabled safe and reliable interconnection of generators to the grid. However, with increasing size of generation, direct interconnection at transmission level was required and hence rules were being developed by different TSOs and regulators [1]. The present study is focused on the technical regulations relating to large RPPs connected to transmission systems. Though regulations such as fault level contribution, power quality, and anti-islanding protection are mostly considered for small RPPs connected to distribution systems [9, 10], they have also been discussed in brief in Sect. 4.2. Table 1 lists the principal grid codes proposed by different TSOs/regulators in the top RPP integrating countries.
Along with the codes practised in the countries mentioned earlier, grid codes in Denmark have been chosen due to the high penetration level of wind power. The Irish grid code is also selected because of its unique system nature [22, 23].