Security Assessment And Total Supply Capability Analysis Of Urban Power Network With Partitions Flexibly Interconnected

Urban power grid is one of the city's major infrastructures.The generally partitioned operation mode in 220 kV and above large power grid is limited to the short circuit capacity and electromagnetic loop network.However,there are also some security risks in partitioned operation mode.The voltage source converter(VSC)based high voltage direct current can improve the controllability of power grid,which is an important development direction.This paper analyzes the static security and total supply capability(TSC)of ACDC hybrid urban power grid with partition flexibly interconnected.The main work is as follows: 1.This paper proposes the related concepts of partition flexible interconnection.Firstly,the operation status and security risks are analyzed for existing partition mode.Then an idea is proposed for urban power network with partition flexibly interconnected based on VSC technology.By this way,the power grid can improve the controllability.Then,the basic characteristics of the partitioned flexible interconnection operation mode are analyzed.Finally,the basic operation modes of partition flexibly interconnected is proposes.2.This paper studies the working principles of flexible DC partition interconnection device.Firstly,the basic structure of partition interconnection device is proposes.Secondly,the working principles of the device are analyzed.The control principles of power flow and dynamic reactive power output range are studied.Then actual power output curve of the device is drawn,and the maximum dynamic reactive power compensation value that the device can actually output is obtained from the curve.3.This paper proposes the security assessment method on urban power grid with partition flexibly interconnected.N-1 static security is the basic guideline in the planning and operation of the power grid.An emergency power support way after the N-1 fault is provided with partitions flexibly interconnected.This paper proposes the security assessment method on urban power grid in this new operation mode.Firstly,the power support strategy between partitions is analyzed.It is proved that partition interconnection device should be arranged in a priority order compared with traditional operation,such as turning on the standby generators and taking the switch.Secondly,the emergency power support strategies of the device are presented,where sensitivity approach is used to determine power support quantity of the device.Finally,iterative calculation is used to eliminate the error.4.This paper proposes the TSC model of urban power grid with partition flexibly interconnectedFirstly,the definition for TSC of partition urban power grid is proposed,considering N-1 static security and transient voltage stability.Then,the model for TSC of partition flexibly interconnected is built,based on steady state power support function and dynamic reactive power compensation function of the flexible DC partition interconnection device.Finally,a simplified approximation method is applied to calculate TSC.5.This paper uses a real pilot project in Beijing to verify the proposed method.According to the plan,the Beijing power grid will be operated in 8 partitions during the summer in 2017.Chang cheng and Cheng shun-shao partitions will be flexibly interconnected with the device.This paper analyzes the promotion effect for security and TSC of Beijing power grid after partition flexibly interconnected.