Shunt-connected Devices Research Articles

Novel nine level switched capacitor multi-level inverter based STATCOM for distribution system

FACTS based devices are mostly used in power systems due to their capacity to improve system stability. The Static Synchronous Compensator (STATCOM), a shunt-connected device in the FACTS device family, is used for power compensation, power balancing, and enhancing dynamic stability in contemporary power systems. In the proposed work, STATCOM based novel nine level switched capacitor based multi-level inverter (MLI) is used to reduce power quality issues. The proposed novel inverter has a few number of switches with one voltage source. The placement of STATCOM based inverters in the wrong places may have detrimental effects on power loss and electricity quality. To overcome these issues, green anaconda optimization (GAO) is used to allocate the proposed system in an optimal place. The performance of the proposed inverter is examined using the MATLAB/Simulink tool. This inverter requires fewer switches and achieves DC link voltage balances in comparison to any other existing conventional topologies. STATCOM based inverter is validated under different faulty conditions to show the effectiveness of this inverter. The proposed new inverter has nine levels and compensates for the poor state while improving power quality. The proposed method has a substantially lower total harmonic distortion (THD) of 1.04 % while maintaining an efficiency of 99.02 %. Experimental validation is established using a dSPACE RTI1104 controller to validate the proposed method. Experimental results obtained 1.04 % of harmonics with the same output voltage as the simulation.

A Literature Review on the Optimal Placement of Static Synchronous Compensator (STATCOM) in Distribution Networks

The existing distribution networks were designed at a time when there was virtually no embedded generation. The design methods ensured the voltage at various parts of the network remained within the limits required by standards, and for the most part, this was very successfully achieved. As Distributed Energy Resources (DERs) started to grow, the rise in voltage due to injected currents and the local impedances started to push network voltages toward, and even above, the desired upper limits. Voltage limits are based on typical appliance requirements, and long-term over-voltages will ultimately result in unacceptably short appliance life spans. Distribution Static Compensators (dSTATCOMs) are shunt-connected devices that can improve low-voltage networks’ performance by injecting currents that do not transfer real power. The currents can be reactive, negative or zero sequence, or harmonic. System performance can be improved by reducing conduction loss, improving voltage profile and voltage balance, or reducing Total Harmonic Distortion (THD). To obtain these benefits, optimal sizes of dSTATCOMs need to be placed at optimal locations within the distribution network. This paper has considered seventy research articles published over the past years related to the optimal placement and sizing of dSTATCOMs. In this study, minimization of power losses, voltage profile improvement, loadablity factor, voltage sag mitigation, and reduction in annual operating costs are considered fitness functions that are subjected to multiple constraint sets. The optimization algorithms found in the literature are categorized into six methods: analytical methods, artificial neural network-based methods, sensitivity approaches, metaheuristic methods, a combination of metaheuristic and sensitivity analysis, and miscellaneous. This study also presents a comparison among distribution network types, load flow methods optimization tools, etc. Therefore, a comprehensive review of optimal allocation and sizing of dSTATCOMs in distribution networks is presented in this paper, and guidance for future research is also provided.

Protection of Control Circuit Rectifiers against Surges from D-C Coil Interruption

The interruption of d-c coil circuits can cause voltage surges destructive to rectifiers. The origin of these surges is discussed, and the use of shunt-connected devices for surge control is described. Calculation methods are given for determining the necessary component values for any required degree of surge reduction, and the time to reach drop-out current with those components. Calculated results obtained by these methods are compared with those shown in the oscillograms.