Research And Application On Coordinated Control Of Thermal Power Boiler-turbine Unit After Microgrids Interconnection

With the rapid growth of microgrid capacity and the random and intermittent characteristics of the microgrid has increasing impact on the grid.The peak load and frequency regulation of the thermal power unit and the rate of response to the AGC command are received more and more attention.How to improve the safety and fast tracking of thermal power units in the grid-specified indicators has important practical significance.The power system must coordinate the actual output between the units to offset the disturbance of the output of the microgrid represented by wind energy and photovoltaic at a certain moment.In China,the thermal power unit still dominates the energy structure,and the role of the thermal power unit in the power grid has also changed from leading power generation to mandatory adjustment,Therefore,higher requirements are put forward for the system of coordinated control of thermal power boiler-turbine unit.In order to increase the rate and stability of the units load response mostly,the specific research contents are as follows:(1)Existing problems in coordinated control.During the load changes of the unit,the deviation of the main command of the steam turbine is large,resulting in poor adjustment accuracy of the load and slow change of the load;The burning rate commands of boiler main control changes frequently,resulting in a low boiler burning rate;The parameters such as coal supply and furnace pressure of the unit fluctuated greatly;The unit responded to the power grid AGC commands for too long and failed to achieve the grid.(2)The choice of the optimization plan.New addition a coordinated optimization control system for the problems of steam turbine main control,boiler main control in the coordinated control system and load overshoot during variable load,and parameters unstable of main operating of the unit;Adopted the condensate throttling optimization scheme to reduce the unit response time by rapidly adjusting the condensate flow rate,for the problem that the response time is long after the unit accepts the grid AGC command.(3)Finally,the proposed optimization control scheme is designed,configured and debugged in the OVATION distributed control system of Huaneng Tongchuan coal-fired generating units.The results showed that the improved unit can respond quickly when the grid AGC command changes within the specified time,the frequency regulation capability is obviously enhanced,and the main parameters of the unit are smoothly transitioned.At the same time,a part of the energy storage in the deaerator and low-pressure heating system are fully utilized,so that the unit as a whole increased efficiency.The analysis and design of the majorization scheme of the coordinated control of thermal power boiler-turbine units has a good application background from the actual project realization,and has a certain reference value for the optimization of power plant furnace control system under the new environment.