The capacitor bank energizing model developed in Simulink is shown in Figure 12. The voltage sag usually takes more than 1 second to rise back to its nominal voltage level. A 1 second simulation time is set and ode23tb solver is selected to run the simulation. The switchgear is set to open at initiate stage and close at 0.06 second during simulation to simulate voltage sag caused by transformer energizing. This model enables the simulation of voltage sag caused by transformer energizing. The simout block is used to store the simulated data for harmonic FFT analysis using the power gui block. The measurements of instantaneous waveform and RMS are located at the 11 kV feeder bus. 4kV, 1 MVA saturable core transformer block to a 10 kW resistive and 100 VAR inductive load. The model consists of an 11 kV, 30 MVA, 50 Hz three-phase source block feeding through a three-phase breaker block to a 11 kV/0. It is used to simulate voltage sag caused by transformer inrush current and core saturation during energizing. The transformer energizing model developed in Simulink is shown in Figure 9. The changes of fault impedance during a fault create a multistage voltage sag power quality disturbance. The fault block is set to simulate fault from 0.1 to 0.168 second with fault impedance of 1 Ω and the multistage fault block is set to simulate fault from 0.168 to 0.3 second with fault impedance of 0.1 Ω. Figure 4 shows multistage voltage sag instantaneous waveforms caused by double line to ground fault.
It is sometimes also defined as multiple faults that occur consecutively within a short interval of time and captured within one single record as one event. The multistage voltage sag is typically due to multiple faults protection relay clearing mechanisms that are not synchronous with each other, thus changing the power system impedance and network configuration leading to multiple stages of voltage sag before fully recovering to its nominal level, or the changes of fault or ground impedance during fault. The line fault model is also capable of simulating multistage line faults. A comprehensive set of basic models developed to simulate voltage sag, swell, transient, harmonic, and flicker power quality disturbance are presented in this chapter.
In this book chapter, MATLAB/Simulink with SimPowerSystems is chosen as the simulation platform. However, the widely used tools in the academic research community are PSCAD/EMTDC, ATP/EMTP, MATLAB with Power System Toolbox, Power System Analysis Toolbox, Simulink with SimPowerSystems blockset, and Power Analysis Toolbox. There are many power system simulation tools available, and each simulation tool has its own merits. With that in mind, modeling and simulation approach became one of the widely used research method to model and simulate various power quality disturbances.
It provides an insight of how power quality disturbance propagates from the source and through the entire power system network. It also allows the researcher to carry out what-if scenarios by changing the model or simulation parameters to test their hypothesis. It allows the researcher to model and simulate a given power system to trace, analyze, and understand the root cause of power quality disturbance.
#Make plots in power world simulator software
With the advancement of computer technology and software development, simulation of power quality disturbance is made possible. To develop the right mitigation strategy for the power quality problem, the power quality disturbance phenomenon and its root cause must be fully understood. Power quality research is the study of various phenomena that cause power quality disturbance to occur and the development of mitigation strategy. Power quality disturbances are categorized into voltage sag, voltage swell, transient, harmonic, voltage notch, and flicker. A single power quality event such as voltage sag caused by a fault in transmission or distribution level may cost the affected industries up to millions of monetary losses. The emergence of smart grids further distinguishes the importance of power quality. It plays an important role to ensure the quality of power being delivered to the industry customer. Power quality is an important branch of power system engineering.
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