Thermal Power Plant Isolated Grid Operation Research

An isolated grid is a grid that operates independently of the large grid.At present,in order to reduce production costs and increase corporate profits,many high-energy-consuming enterprises in the country usually build their own power plants for isolated grid operation.These power grids have fewer generators,small system capacity,and high sensitivity to power disturbances,and can cause grid collapse under extremely harsh working conditions,causing serious production accidents or even personal accidents,and serious business losses.For this reason,this article takes Shanxi Zhaofeng Aluminum’s isolated grid system as the research object,analyzes the operation mode of the isolated grid,explores the stable control scheme of the isolated grid when the voltage and frequency fluctuations exceed expectations,and finally stops the isolated grid system suddenly.The black start scheme of the time was studied.First,the isolated grid operation mode of Zhaofeng Aluminum’s self-provided power plant is studied: the feasibility of isolated grid operation is explored,and the matching of unit output and load demand is analyzed;the isolated grid structure is studied,and the isolated grid is explained.Generator installed capacity,operation mode and typical primary and secondary load.Then,the transient stability control strategy of the isolated grid is studied: the concept of system safety and stability control is pointed out,and the voltage drop caused by the large-scale AC motor in the factory area is proposed,and the motor soft start scheme is proposed for the possible occurrence of the isolated grid during operation.The frequency is greatly reduced due to the unit shedding,and a load shedding plan for low-frequency load shedding is proposed;the function and configuration principles of the stability control system are analyzed,and the stability control system of the isolated grid of Zhaofeng Aluminum Plant is designed,and coordinated control is given.The action plan of the strategy.Finally,the black start strategy of the isolated grid is studied: the load situation of the Zhaofeng Aluminum Plant that needs black start is analyzed,and the capacity of the diesel generator set for the black start is calculated based on this,and the main wiring of the diesel generator is given;The pros and cons of the two recovery strategies of serial recovery and parallel recovery,combined with the actual situation of the isolated network,proposed a recovery strategy combining the two strategies,and gave the black start process and scheme.This article proposes measures to maintain grid security;the simulation verification of the two safe and stable control schemes,soft start and unit shedding,confirms that the proposed scheme is maintaining The effectiveness of voltage and frequency stability;the black start scheme proposed in this paper has been simulated and verified,and the results have proved its accuracy.