Abstract
To meet the rapid growth of electricity demand and reduce carbon intensity, China is developing renewable energies rapidly including hydropower, wind and solar power. Due to the geographical mismatch of energy sources and demands in China, many long-distance and large-scale UHVDC and HVDC transmission projects have been built to transmit electric power from the western renewable bases to eastern coastal load centers. Some provincial power sources serve both local demands and deliver power to multiple regional power grids via HVDC transmission lines. As large capacity HVDC power transmission projects have great impacts on receiving-end power grids. Thus, the local exporting power grid should consider both local demands and energy importing area demands. A mixed-integer linear programming day-ahead peak shaving model to minimize the peak-valley difference in residual load after renewable generation of multiple power grids is developed. The model uses chance constraints to compensate for forecast errors of wind and solar power with hydropower, and introduces maximum daily power regulation times and stair-like power curve constraints of HVDC tie lines to avoid frequent HVDC power change and ensure power grid safety. The case studies in Yunnan province, which has large scale hydro, wind and solar power sources and delivers power to multiple regional power grids via HVDC transmission lines, shows the proposed model can shave peaks from multiple power grids effectively, hydropower can compensate for wind and solar forecast error and obtain satisfying results for multiple power grids, and that HVDC constraints can avoid their frequent power change and ensure the power grid safety.
Highlights
China has seen fast economic development and rapid electricity demand growth in recent years [1]
This study presents a model for day-ahead scheduling of hybrid hydro-wind-solar power system which serving power for the local power grid and multiple receiving power grids via Highvoltage direct current (HVDC) transmission lines
This study presents a new multiple power grids peak shaving model considering coordinated operation of the hydro-wind-solar generation system that serves both the local power grid and several regional power grids via HVDC transmission lines
Summary
G, g Number of grids and index of power grid. T, t Set and index of time periods M, m Set and index of hydropower plants. Upper and lower change limit of HVDC line r at period t. Binary variables to mark if power change of HVDC line r is positive or negative at period t. Minimum continue periods that power of HVDC transmission line r should keep static or keep change in single direction Binary variable to mark if the power is change positive of negative during the stair periods Allowable daily power change times of HVDC line r Lower and upper limits of daily electricity delivered to power grid g Positive compensate confidence level Negative compensate confidence level Storage of reservoir m at period t. D. FUNCTIONS ft (·) Estimated probability density function ftW (·) Estimated probability density function of wind power
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