Research On The Analysis And Scheme Of Large-scale Industrial Grid Islanding Operation

The paper relies on a real large-scale petrochemical enterprise to study itsreasonable island configuration scheme, in order to avoid voltage and frequency collapsedue to bad faults during normal operation or other extreme reasons.Firstly, the paper analyzes three impact factors on the operating stability whenenterprise islanding: load model, generator model and SVC. After the failure, motorsabsorb larger amount of reactive power and voltage collapse may be caused. Impact ofchanges in the electrical parameters of the motor and load characteristics and constituteon the basic stability of the island is due to this reason. Generator parameters, primarilythe governor difference coefficient and inertia, can change the response ability of thegovernor and generator and influence the changing rate of grid frequency andlow-frequency protection action rounds. SVC devices will bring about some adverseeffects in reducing the loss of load and recovery frequency during transient process.Typically the traditional method of low-frequency load shedding measure is takenwhich is configured as the primary means of control, but through the analysis of theoryand the whole process of simulation under the harsh fault, defects and inapplicability arefound. As the petrochemical enterprise is a class load, minimizing the load loss is neededto ensure the integrity of its production process. On the base of summary of theinadequacies of conventional configuration scheme and characteristics of underfrequency and voltage protection, a coordination strategy between under frequency loadshedding and low voltage trip is proposed. And the setting values between them arechecked. Combined with the voltage and frequency variations trajectory, the generalprocess and specific scheme of the coordination configuration of the low-frequency andlow-voltage protection are given to ensure that the enterprise grid safe and stableoperation.