Zakir Hussain Rather

Large-scale renewable energy integration and consequent displacement of synchronous machines result in low system inertia. Low system inertia leads to high rate of change of frequency, higher frequency nadir, and potentially require higher primary frequency reserve to stabilise system frequency following a sudden generation shortfall. To address such frequency stability issue in wind energy integrated system, this paper has proposed a new and realistic control strategy for inertial and primary frequency support from HVDC connected Offshore Wind Farms (OWF). The proposed control strategy, which is based on offshore AC voltage control is not only avoiding limitations of high rate of frequency change in the offshore grid, but also does not result in any frequency deviation in the offshore grid while providing frequency support to the main grid. The proposed control strategy is robust for any frequency deviation in the main grid, and utilises HVDC converters to map onshore frequency variation in to voltage variation in the offshore grid, thus enabling adequate inertial and primary frequency support from the OWF. The proposed control strategy has been tested on two test systems and the results are compared with conventional method to demonstrate the robustness, effectiveness and reliability of the proposed frequency support strategy.

In conventional power systems, synchronous generators have been the main source of dynamic reactive power. However, displacement of conventional power plants by non-synchronous generation resources, such as Wind Power Plants (WPPs) and other Renewable Energy Sources (RESs), result in diminished dynamic reactive power reserve at system level. System operators in various countries are planning to tackle this issue by introducing dynamic reactive power reserve as a new ancillary service product. In this paper, reactive power capability of Type-4 wind turbine based WPP considering practical constraints is explored. A new and effective centralized WPP capability based control strategy is proposed to supply dynamic reactive power from a WPP, particularly, beyond grid code requirement. An adaptive method to dispatch reactive power from Wind Turbine Generators (WTGs) in a WPP, is also proposed. In the presented study, wake effect and detailed WPP model are taken into consideration. The proposed strategy is implemented on three wind integrated benchmark power systems developed in DIgSILENT PowerFactory platform using IEC 61400-27-1 standard model of WTG.

In this paper, a novel wind farm control strategy is proposed to mitigate voltage dip induced frequency excursion in wind integrated power systems. In the proposed control strategy, conventional fixed reactive/active current injection priority is replaced by an optimum adaptive priority based reactive and active current injection. The control problem is formulated as binary integer optimization problem, which simultaneously minimizes active power shortfall from wind generation during fault and complies with grid code requirements. Detailed wind farm model and wake effect are taken into consideration to achieve realistic response from the wind farm, while IEC 61400-27-1 wind turbine generator model is adopted for wind turbine modelling. Dynamic model of the test system has been developed in DIgSILENT PowerFactory, while the static model is also developed in MATLAB, and co-simulation platform has been used to test and validate the proposed control strategy.