| The great challenges confronting the stability of power system operation are due to the vigorous growth of new energy and the continual enlargement of power system interconnection.Once the fault occurs without taking timely measures,it is very likely to cause the spread of the fault,culminating in the extremely effects of a blackout.To guarantee the safe operation of the power system,the transient stability analysis of the power system must be carried out after the fault,and effective control measures should be taken in time to calm the negative impact of the fault on the system in the cradle.China has realized the continuous optimization of the energy structure under the guidelines on peak carbon emissions and carbon neutral that Chinese authorities enacted.As an important support for the wide application of new energy,energy storage technology has good energy balance and buffering effect,which can effectively inhibit the growth of instantaneous power in the system and has broad application prospects in improving the transient stability of power system.This paper makes an analyze of the transient stability characteristics of multi-machine systems under single-machine group,based on Single Generator Equal-Area Criterion(SGEAC),and proposes a way to select the energy storage location by taking into account first-order sensitivity of transient stability margin and node active power.Building the model of transient energy storage by the Power System Analysis Software Package(PSASP)user-defined(UD)module.After a fault occurring,the energy storage grid-connected measures are taken to study the effect of energy storage grid-connected on improving transient stability,and researching the derivative effect of energy storage grid connection on improving transient stability,that is,to examine the inhibition effect of energy storage on cascading failure.Firstly,in order to analyze the stability of multi-machine system from the view of single machine,this paper introduces the transient energy conversion process and stability characteristics of rolling ball motion in the kinematics,and the single machine stability characteristics of power system including dual machine system,infinite bus system and the power system in COI coordinate are analyzed.Finally,the stability characteristics of single machine and single machine group of multi-machine system based on SGEAC in COI coordinates are obtained.The CEPRI-36 node has been set with a three-phase short-circuit fault,and the stability characteristics of the critical machine and the critical cluster are analyzed and calculated,and the transient stability margin of the example is given.Secondly,in order to study the effect of energy storage grid connection on improving transient stability,in this paper,the idea of trajectory calculation is used to solve the sensitivity of each parameter in the transient process,and obtains the transient stability margin sensitivity of the critical cluster as the basis for site selection.The energy storage transient model is built in the PSASP user defined(UD)module,and the effective applicability of the model in the EPRI-7 node system is simulated and analyzed.Verifying the accuracy of the proposed location method on CEPRI-36 node system with the energy storage model applying in.After conducting a simulation,analyzing the mechanism,and computing the acceleration area,deceleration area,and transient stability margin of the system critical cluster following energy storage grid connection,analyzing the ameliorative function of energy storage grid connection on transient stability.Finally,in order to study the derivative effect of energy storage grid connection on enhancing the transient stability,this paper studies the effect of energy storage on cascading failures.After briefly introducing the background of cascading failure and the possible harm to the system,the failure occurs when the system is set in three states of normal load,heavy load and light load in the CEPRI-36 node example.Combining theory and simulation,it is verified that energy storage can further suppress cascading failures while improving system transient stability. |
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