Grid-connected Distribution System Research Articles

Hybrid Taguchi-based Technique for Micro-phasor Measurement Units Placement in the Grid-connected Distribution System

The bidirectional flow of electrical power has aroused the need to monitor the distribution system (DS) in real time so as to avoid issues related to grid stability, which can cause cascade failure. A micro-phasor measurement unit (µ-PMU) is an equipment proficient in monitoring the DS in real time. A premeditated placement of µ-PMUs is therefore desired due to the technical and economic restraints. In the present paper, a novel hybrid technique that incorporates the Taguchi method (TM) and enhanced version of the binary particle swarm optimization (BPSO) by utilizing V sigmoid function and constriction factor is employed for the optimal location of µ-PMUs in the DS. The Taguchi scheme produces an improved population at the initialization stage, which finally eludes early convergence, and thus, it makes BPSO further robust. The study takes into account the optimal number of µ-PMUs required for the complete DS observability, economy, and the measure of reliability. The proposed method has been effectually applied to Indian 85-bus radial DS and standard IEEE distribution feeders, namely 34-nodes, 37-nodes, 69-nodes, and 123-nodes systems. A comparative analysis has been carried out to substantiate the superiority of the proposed method over the existing methods.

Fuzzy with Hysteresis Controller for Power Quality Improvement of Grid Interconnected System

The grid connected distribution systems are providing the energy to the load from the grid. During the period of energy transmission, the issues are occurred on the power quality in transmission line. In the power system, the power quality issues are occurred due to the following issues as instability of the system, voltage sag, harmonic distortion, over voltage, unbalanced voltage etc. In this paper, the power quality improvement is designed using the inverter which compensates the voltage and current when the fault occurred. This inverter is used to inject the power using a DC source. This improvement of power quality is controlled by the hysteresis controller with fuzzy logic control. The feedback is given to the controller which reduces the error from the system and provides the control variables to the inverter terms of switching gate signals.

PV installation for grid-connected distribution system in Savannakhet Province, Lao People's Democratic Republic

PV installation for grid-connected distribution system in Savannakhet Province, Lao People's Democratic Republic

Modeling Load Dynamics to Support Resiliency-Based Operations in Low-Inertia Microgrids

Microgrids have repeatedly demonstrated the ability to provide uninterrupted service to critical end-use loads during normal outages, severe weather events, and natural disasters. While their ability to provide critical services is well documented, microgrids present a more dynamic operational environment than grid-connected distribution systems. The electrodynamics of a microgrid are commonly driven by the high inertia of rotating generators, which are common in many microgrids. In such high-inertia systems, the impact of end-use load electromechanical dynamics are often not examined. However, with the increased penetration of inverter-based generation with little or no inertia, it is necessary to consider the impact that the dynamics of the end-use loads have on the operations of microgrids, particularly for a resiliency-based operation. These operations include, but are not limited to, switching operations, loss of generating units, and the starting of induction motors. This paper examines the importance of including multi-state electromechanical dynamic models of the end-use load when evaluating the operations of low inertia microgrids, and shows that by properly representing their behavior, it is possible to cost effectively size equipment while supporting resilient operations of critical end-use loads.

Analytical Approach to Reactive Power Dispatch and Energy Arbitrage in Distribution Systems With DERs

This work proposes an analytical approach for reactive power dispatch and energy arbitrage in grid-connected distribution systems with distributed energy resources. The comprehensive approach minimizes the operational cost of the system while incorporating the price of electricity, cost of reactive power, reactive power charge, line losses, and energy arbitrage. Mathematical programing and metaheuristic algorithms have been employed as benchmarks, and the efficacy of the analytical approach was validated on 69 and 119-bus radial distribution systems with real solar irradiance and electricity price data. The proposed approach removes the dependence on initial solutions and parameter tuning, shows superior results compared to the benchmark algorithms, and is up to 100 times faster compared to existing algorithms commonly used. It is therefore suitable for both day-ahead and real time power dispatch applications.

Advanced islanding detection utilized in distribution systems with DFIG

The penetration of distributed generation (DG) in electrical power systems is rapidly increasing these days and more attention is drawn to maintain a healthy distribution system. Islanding operation of DGs is one of the biggest challenges to the distribution system stability. Fast and accurate islanding detection can avoid the possibility of damages to the DGs when they are un-intentionally reconnected to the grid and also provide useful information to the protection and automation design of the stand alone operated system. Rate of change of frequency (ROCOF) method is one of the most commonly employed anti-islanding protection techniques, it offers fast detection and easy implementation. However, it is often easily affected by the system disturbance and might not able to detect the islanding situation if the power imbalance between the DG and the load is small. This paper investigates an inter-lock method which can improve the performance of rate of change of frequency (ROCOF) by applying system impedance estimation. It was found that this new method can help in verifying the ROCOF relay islanding detection and avoiding false operations of ROCOF in a grid connected distribution system which has large load variations. The proposed method was verified using the experimental testing results derived from both an experimental testing model which includes an 8kW Double Feed Induction Generator (DFIG) and a 9MW DFIG simulation system.

Islanding and Non-Islanding Detection for Grid Connected Distribution System

In this paper, wavelet transform based approach is proposed for islanding detection in a distribution system. The negative sequence voltage and negative sequence current obtained due to disturbances are measured at the point of common coupling (PCC) and given to the wavelet processing module to extract features like standard deviation and energy content. The negative sequence voltage and current components are decomposed under various levels to filter out lower frequency components. From the obtained features suitable threshold value is fixed for classifying the islanding and non-islanding events.