Coordination Method Of Regional And Provincial Power Grids With Regulating-Pressure Index

While the eastward transmission capacity of hydropower in Southwest China has increasing rapidly, at the recipient end, several provincial grids are lacking of reserve capacity during light load time, i.e., huge regulating pressure, with load allocated by the regional power grid. The coordination between regional power grid and provincial power grids is a multi-object non-linear optimization problem with high-dimension constraints. It is crucial for efficiently absorb abundant hydropower in Southwest China, which requires practical methods.This dissertation takes East China Power Grid, which is the main recipient end of West-East Electricity Transfer Project, as the research background. Based on the analysis of load curves and energy sources in each provincial grids of East China, it proposed a coordination method of regional and provincial power grids with regulating-pressure index. The results and conclusions will be introduced as follows:(1) It proposed a regulating-pressure index, which consists of ramping index and reserve capacity index. The ramping index is to describe capability of the grid to respond its load curve’s fluctuation in two neighboring time intervals, it is influenced by fluctuation of load curves in two neighboring time intervals as well as ramp rates of units of the grid. The reserve capacity index is to describe capability of the grid to respond the forecasting errors between the load curve utilized to make day-ahead scheduling and the real-time load curve happens that day. The reserve capacity index is influenced by the limitation of unit-output and reserve capacity required by the grid for security. The regulating-pressure index is a dynamic index, which varies among time. It combined information both from load curve and energy sources. The regulating pressure index is dimensionless, which means comparing regulation pressure among multiple grids whose load and power generation capacity varies among each other, is reasonable and objective. The regulating-pressure index offers principles and information for coordination method of regional and provincial girds.(2) A method for coordinating pumped storage plants, hydropower plants and thermal power plants operated by the regional power grid is given. The case study illustrates that comparing with scheduling plans adopted by the grid, the given method could further decrease the difference between peak load and valley load, and improve load factors, which relieve the grid’s pressure for regulating.(3) It proposed a method for load allocation among multiple grids with regulating-pressure index. The dimensionless index makes it reasonable and objective to compare regulating pressure among multiple grids, whose load and power generation capacity differs obviously from each other. The results could satisfy demands from multiple grids for regulation service, and also can satisfy the constraints of ramping rate as well as reserve capacity of each unit in each grid. Unlike allocation methods by percentages or load curves, load allocating by regulating pressure index can take fully advantage of information from each grid’s load curve and energy sources, which optimized the resources allocation on a grid of grids.