摘要
Integration of wind- and solar-based generation into the electric grid has significantly grown over the past decade and is expected to grow to unprecedented levels in coming years. Several jurisdictions have set high targets for renewable energy integration. While electric grid operators have managed the variable and non-dispatchable nature of wind and solar power at current levels, large-scale integration of these resources would pose new challenges. In particular, the variable nature of wind and solar may lead to new electric grid operation and planning procedures.Net load in electric grids is defined as the conventional load minus the non-dispatchable generation. Net load is the basis of operation planning in day-to-day delivery of electricity to the consumers. With large-scale integration of wind and solar power, the net load in the system would be significantly affected. In this paper, we focus on characteristics of net load in electric grids when a large amount of wind and solar power generation is integrated into the grid. We use the data from California׳s power system. California intends to produce 33% of its electricity from renewable resources by 2020, 80% of which is expected to come from wind and solar power. We use both historical data and simulated scenarios of future wind and solar power generation. For future scenarios, we use the data provided by National Renewable Energy Laboratory to generate wind and solar power integration scenarios for years 2018 and 2023. The simulated net load data are analyzed from a variety of perspectives, such as average daily shapes, load and net load factor, duration curves, volatility, and hourly ramps. The results showed that compared to conventional load, characteristics of net load would be significantly different and need to be taken into account when designing measures and mechanisms for operating electric grids with high penetration of renewables.