Mid-long term voltage stability evaluation method for receiving-end power grids

Abstract

The invention relates to a mid-long term voltage stability evaluation method for receiving-end power grids. The method comprises the steps of building a full process dynamic simulation program model, of considering slow dynamic component movement, for partition running receiving-end power grids; obtaining voltage weak nodes corresponding to the partition running receiving-end power grids; obtaining a PV curve of the voltage weak nodes before and after the slow dynamic component movement in the mode of slow growth of a load; determining a power limit point of the PV curve of the voltage weak nodes after the slow dynamic component movement; obtaining a state transition curve of the power limit point and determining an intersection point of the state transition curve and the PV curve of the voltage weak nodes before the slow dynamic component movement; and evaluating the mid-long term voltage stability of the receiving-end power grids according to data corresponding to the intersection point of the state transition curve and the PV curve of the voltage weak nodes before the slow dynamic component movement. By the method provided by the invention, the voltage stability of the receiving-end power grids can be effectively monitored; and the safe and stable operation level of an interconnected power grid is improved.

Description

technical field [0001] The invention relates to the field of power grid safety and stability control, in particular to a method for evaluating medium and long-term voltage stability of a receiving end power grid. Background technique [0002] With the rapid development of my country's large-scale EHV / UHV AC-DC interconnected power grid, various new equipment and new technologies of the power system have been put into operation and applied continuously, and the dynamic behavior of the system has become more complex, which makes the intermediate state after the transient process The problem of long-term voltage stability is becoming more and more prominent and has gradually attracted great attention of power system researchers. It is particularly important to construct stability criteria and safety and stability control measures suitable for medium and long-term dynamic processes to prevent urban power grid voltage collapse. In the medium and long-term dynamic process, the mai...

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Problems solved by technology

[0004] In order to study the influence of slow-moving components in the medium- and long-term dynamic response process, the existing research replaces the medium- and long-term dynamic process with its quasi-steady-state equilibrium equation, using quasi-steady-state approximation, which has the characteristics of fast simulation calculation speed and clear physical concepts, but The accuracy of the generator model and load model is poor

Combined with the characteristics of medium and long-term stability, quasi-static assumptions are introduced, and a fast simulation algorithm is proposed, but there are still deficiencies in the control of the simulation step size, which makes the simulation calculation time longer

From the perspective of solving the nonlinear algebraic-differential equations of the power system, the dynamic impact of OLTC action on voltage stability is analyzed based on the discrete model of the on-load tap changer. There is a problem that the static analysis model does not consider the process of generator reactive output adjustment. There will be a large deviation in the application

Using the Thevenin equivalent method will retain all generators and load nodes, which overcomes the shortcomings of the traditional Thevenin equivalent process that the parameters are not easy to identify and cannot reflect the dynamic changes of the generator, but the equivalent parameters of all generators must be in OXL It needs to be re-obtained during operation, the process is complex and the amount of calculation is large, which limits its application in the actual large power grid

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