Electricity Pinch Analysis Method

Abstract

Under the impetus of low-carbon transition goals in energy and power system, the proportion of new energy sources on the supply side, which are characterized by high randomness, high uncertainty, and the difficulty of long-term forecasting, continues to increase. The planning principles, modeling, and solution methods of new power systems based on classical probability theory and stochastic optimization theory face many challenges, such as poor reliability of planning results, difficulty in interpretation, and low efficiency. The theory of electricity pinch analysis(EPA) is established in this paper based on the basic principles of pinch analysis. The fluctuation characteristics of sources and loads are analyzed in the frequency domain through Discrete Fourier Transform (DFT), and the assessment indicators of "flow" and "quality" of electricity are defined, along with balance equations. The graphical method of EPA is proposed, and the source/sink composite curve is constructed to determine the pinch point that marks the power balance with the minimum demand for thermal power. Sinks and sources are constructed, utilizing the frequency domain characteristics of net load and energy storage, respectively. A planning method of power system source and storage based on EPA is developed and applied to the provincial grids in China. The results indicate that the electricity surplus is 4.23 $$ 10⁷, 3.45 $$ 10⁷, 3.06 $$ 10⁷ kWh in 2021, 2022, and 2023, respectively, with a difference of no more than 4.5% from the actual data. Considering long-duration energy storage reduces the demand for thermal power from 21,882 MW to 20,242 MW. By further categorizing long-term energy storage into three types: 6,000 hours, 720 hours, and 168 hours the storage capacity requirement is halved compared to the scenario with only two types. Thus, the effectiveness of the method is validated, and it may contribute to a paradigm shift in the planning of new power system.