Control strategy study on frequency and peak-load regulation of coal-fired power plant based on boiler heat storage capacity

Abstract

Nowadays, quantity of coal-fired power plant and its single unit capacity are greatly improved in China, and power grid’s frequency and peak-load regulation range become wider. Based on the basic regulation theory and unit’s characteristics, this paper indicates the limitations of unit’s original control strategies and such limitations have produced great damages to coal-fired boilers through assessment of 2 years statistical data of boiler tube explosion in regional power grid. Under field tests, the quantified boiler heat storage capacity of six typical thermal power units in the power grid is provided. Comparisons of these six coal-fired boilers are made for getting the relationships between BHSC and boilers’ tube explosion ratio under the in-depth frequency and peak-load regulation. The results show that unit’s boiler heat storage capacity varies greatly amongst boilers with different types and is inversely proportional to boiler’s installed capacity and steam parameter class, and boiler heat storage capacity is inversely proportional to boiler’s tube explosion ratio, which is in conformity with the theory analysis. After that, in-depth frequency and peak-load regulation tests of thermal power units are carried out, respectively. The results show pulverized coal-fired boiler with small boiler heat storage capacity is not suitable for in-depth frequency and peak-load regulation for the safety of power grid and unit itself, while the circulating fluidized bed boiler and pulverized coal-fired boiler with larger boiler heat storage capacity have better adaptability for these functions. Some effective control strategies of frequency and peak-load regulation are presented in load’s rate and range by boiler heat storage capacity of units.