Among the FACTS device, the distributed power flow controller (DPFC) is a superior device. This can be evaluated after eliminating the dc capacitor between shunt and series convertors of the unified ...power flow controller (UPFC) and placing a number of low rating single phase type distributed series convertors in the line instant of using single large rating three phase series convertors as in the UPFC. The power flow through this dc capacitor as in the UPFC now takes place through the transmission line at a third harmonic frequency in the DPFC. The DPFC uses the D-FACTS that allows the replacement of a large three-phase converter as in the UPFC by several small-size series convertors present in the DPFC. The redundancy of several series convertors increases the system’s reliability of the power system. Also, there is no requirement for high voltage isolation as series convertors of the DPFC are hanging as well as single-phase types. Consequently, the DPFC system has a lower cost than the UPFC system. In this paper, the equivalent ABCD parameters of the latest FACTSdeviceDPFChave been formulated with the help of an equivalent circuit model of the DPFC at the fundamental frequency component. Further, the optimal location in the transmission line and maximum efficiency of the DPFC along with Thyristor Controlled Series Compensator (TCSC), Static Synchronous Shunt Compensator (STATCOM) and UPFC FACTS devices have been investigated using an iteration program developed in MATLAB under steady-state conditions. The results obtained depict that the DPFC when placed slightly off-center at 0.33 fraction distance from the sending end comes up with higher performance. Whereas, when the TCSC, STATCOM and UPFC are placed at 0.16, 0.2815, 0.32 fraction distances from sending end respectively give their best performance.
Modern distribution systems consist of various distributed generators (DG) to make reliable power systems. In these DG integrated distribution systems, coordination of overcurrent relays is a big ...challenge for protection engineers. With the addition of DG, distribution system experiences change in the short-circuit level of the system and thus earlier relay settings causes mal operation of relays. Nowadays, various programming optimization techniques are frequently used to find optimal relay settings of overcurrent relays. This paper presents a comparative study of particle swarm optimization and Gravitational Search Algorithm for the coordination of overcurrent relay for a system containing DG. A proper combination of primary and backup relay is selected to avoid mal operation of relays and unwanted outages when DG is penetrated. Practical cases with different DG penetration level and fault types are also thoroughly discussed. A 4-bus radial system is simulated in PSCAD/Simulink platform and programming is done using MATLAB software.
This article presents a hybrid optimization technique particle swarm optimization-gravitational search algorithm for optimal over-current relay coordination. The main contribution of this article is ...to find the optimized relay settings during variation in environmental factors that affect distributed generation performance. The detailed model of wind and photovoltaic source, modeled in a PSCAD/EMTDC platform is penetrated in a 13-bus distribution system. The optimal relay settings are found for different cases, including change in wind speed, change in penetration level, change in cell temperature, and insolation level of photovoltaic. A comparison of particle swarm optimization-gravitational search algorithm with particle swarm optimization and gravitational search algorithm technique is also done, and it is shown that the particle swarm optimization-gravitational search algorithm is a superior method that can be applied in relay coordination tasks.
Lowering real PL and maintaining an appropriate VP are the two key concerns that distribution system utilities are worried about. Several techniques such as capacitor, DG, DFACTS allocation, and ...network reconfiguration have been suggested by the researchers to achieve this goal. One of the methods that can help raise the network VP to a reasonable level and reduce PL is the DRP, which is customers’ response to changing prices of electricity, urging them to lower their usage during periods of peak load. Consequently, in this study, DRP has been used to raise the network VP and manage the system loss. Load modeling is conducted utilizing the concept of demand elasticity with respect to price. Hourly variation of the seasonal load is considered. The impact of DRP on an hourly variation of active–reactive load and each line flows has been analyzed. To determine the VP and electrical PL of the test system, BFSLF method is used with the amended load data once the modified demand based on DRP has been received. The DRP that is utilized for analysis of the distribution network is time of use. The method under consideration is assessed on a RDS, specifically the standard IEEE 33-bus. It is seen that significant losses are reduced, along with VP improvement. The distribution utilities may find the suggested technique to be of utmost significance to enhance the VP along with the reduction of loss. Also, the technique is beneficial to utility as well as the customer, thus maximizing social welfare.
The article discusses about Directional Overcurrent Relays (DOCRs) coordination for the distribution system with DGs integrated. Disparate DOCR characteristic is utilized to mitigate the protection ...issue in all mode of grid operation. The fault current level in the system varies with the change in network condition. Consequently, conventional protection scheme fails to operate and hence optimal relay coordination of (DOCR) arises. In this manuscript, the impact of utilizing different DOCR characteristics has been investigated for mitigating this problem. Extensive research studies have been conducted for estimating the impact of change in operating mode of microgrid on protection coordination. In this work initially the microgrid was designed with 6 bus distribution system. Consequently, the impact on total relay operating time and Coordination Time Interval (CTI) for different relay characteristic has been observed for Grid-connected as well as Islanded modes of Microgrid operation. Subsequently, the key parameters are calculated in terms of CTI, operating time, TMS, PS etc. Further, percentage reduction in the sum of operating time of all the relays with mix curves is obtained to be 22.41 % for grid connected mode and 9.79% for islanded mode with NI characteristic.
The present study is focussed on a comparative analysis of different meta-heuristic optimization approaches for directional overcurrent relay (DOCRs) coordination which has been discussed and ...presented in the literature. Further, to have a comparative analysis of the performance of the optimization methods discussed they have been tested on power system network of different sizes. To overcome such issues, this work proposed a simplex linear programming technique-based overcurrent relay method using general algebraic modelling system (GAMS). The execution of this work is done on the MATLAB 2018 a platform. Based on the obtained result the best meta-heuristic optimization method for mitigating the problem of relay coordination has been identified. Nevertheless, the operating time of the relay is high, so the fault is not corrected at a time. The developed model has been tested on test system of different sizes namely IEEE 9 bus and IEEE 14 bus system. The obtained values through series of simulation are compared with different methods for proving the proposed protection coordination scheme is more effective and efficient than others in terms of operating time and coordination time.
With the increase in Distributed Generation (DG) in distribution systems to maintain the reliability of the supply, there occurs problem of relay coordination. Therefore, it has become important to ...address this issue as it has become a big challenge for the power system protection engineers. With the incorporation of DG, the radial nature of distribution system is lost and short circuit level is also increased therefore, it leads to maloperation of relays as the previous settings of the relays needs to change. The goal of this paper is to address the issue of relay coordination at different wind speeds encountered by wind turbine. GA and PSO optimization techniques are applied to achieve optimum coordination of over-current relays in a three bus system with a detailed model of wind used as Distributed Generation. MATLAB and SIMULINK have been used for all programming and simulation requirements.
From few decades, the growth in electricity demand and increase in nonlinear loads increase the requirement of high Voltage stability for electrical power system. The voltage of the power system can ...be monitored and controlled continuously using voltage stability indices. In this paper firstly contingencies are ranked based on their voltage stability margin, then line stability index (Lmn), fast voltage stability index (FVSI) as well as line stability factor (Lqp) methods are employed to find the most critical line of the IEEE 14-bus system. These three voltage stability indices have been analyzed under top five different contingencies to detect the most critical bus of the system. Static Synchronous Series compensator (SSSC) has placed in top five critical lines and voltage stability indices are observed for optimal location of SSSC.
