This paper presents a Dynamic Uninterruptible Power Supply ((DUPS)) consisting of both battery and flywheel energy storage systems with the aim of overcoming Power quality problems such as temporary voltage drop and Power outages. To Supply a critical load at the moment of fault occurrence and a few seconds later, the flywheel energy storage system(FESS) and for a few minutes after that or in the case of Power outage, the battery storage system and after that, a diesel generator are used respectively. The FESS system consists of a bidirectional inverter, a flywheel and an interior permanent magnet synchronous motor (IPMSM). In the IPMSM control scheme, vector control, torque maximization per ampere(MTPA) and field weakening technics are used. The battery energy storage system consists of a bidirectional DC / DC buck-boost converter and a charge-discharge control. The simulation results show that the FESS changes from standstill to charged and standby condition in less than10  seconds and is ready to Supply critical load for short-term phenomena. In UPS mode, it also maintains the critical load voltage at the nominal value in less than one cycle. In the event of a long-term Power outage, after discharging the flywheel energy for about 2 seconds, the battery energy storage system maintains the DC link voltage at its reference value and provides the necessary time to start the diesel generator.

The purpose of this study is to modeling the factors affecting Supply chain optimality based on the system Dynamics technique in the Power industry. The present study uses a hybrid approach to develop a qualitative-quantitative approach to formulate and validate the factors influencing the Supply chain optimality. To elaborate and identify the optimal factors, from content analysis and thematic analysis using Novio software to construct themes, a qualitative model of factors influencing Supply chain optimality was designed. On the optimality of the Supply chain, 23 experts and experts in the electricity industry with purposive sampling method were selected. In the quantitative part, the system Dynamics method was used for modeling, and then the data collected was analyzed by Venice software. This simulation was carried out over a one year period and represents a long-term horizon. Then the results of this simulation were presented and interpreted on the variables studied. Determining the relationships between variables and the types of variables can lead to a better understanding of the issue and to making appropriate decisions on the Supply chain optimality problem.

In this paper, a new configuration for delta conversion UPS is proposed, which could help the system for better utilization of the UPS inverters. In this configuration, parallel and series inverters of the conventional delta conversion UPS, under the grid fault conditions, are connected in parallel which help to share the load Power and this results in utilizing the series inverter during fault mode. Therefore, using this configuration not only decreases the total capacity of the UPS inverters, but also decreases the system total cost. In the proposed configuration, two inverters have the same sizes and specifications which results in the system modularity that simplifies its implementation and maintenance and reduces the manufacturing and life cycle cost of the UPS system. In addition, the proposed configuration increases the system reliability. To illustrate proper operation of the proposed configuration, some simulations are carried out under the different conditions. The given simulation results validate appropriate operation of the proposed configuration.

In this paper, a simpler implementation of the well-known droop method for the control of parallel Uninterruptible Power Supply (UPS) systems is presented. In this method, in the Power-sharing control scheme, the output current is calculated by software without the need for a current sensor, resulting in a simpler and cheaper structure. By doing so, the number of feedback sensors is reduced from three to two. The paralleling strategy uses the droop method in which the control strategy is based on the drop in the inverter output frequency and amplitude. The application of Proportional-Resonant (PR) controllers is also extended to parallel inverter and its superior performance over the well-known Proportional-Integral-Derivative (PID) controller is shown. To show the performance of the proposed system, a system of two-parallel connected UPS is simulated, and two types of linear and non-linear loads are considered. The non-linear load is compliant with the IEC 62040-3 standard for class I UPS. The results show that the reduction of sensors results in no error, and the control system performance is quite satisfactory. To verify the proposed concept, a two-625VA UPS system is implemented. Several tests on both linear and non-linear loads are performed and the results, which are in good agreement with those of the simulations, are provided. The results indicate that the proposed parallel inverter control structure provides a better system in terms of performance parameters.

AC railway traction loads are usually huge single phase loads. As a result, a significant amount of Negative Sequence Current (NSC) is injected into utility grid. Moreover, harmonics and consumption of reactive Power are further Power quality problems that the Supply network is encountering. In this paper, a compensation strategy with the aid of Railway Power Conditioner (RPC) is proposed to overcome the above-mentioned problems. Firstly, different kinds of traction transformers are evaluated and Y/Δ traction transformer is chosen. Then, a compensation strategy is initiated that is valid for all kinds of traction transformers and a control system is proposed based on that. Finally, the correctness of the analysis and proposed strategy is verified by the simulation results using Matlab/Simulink software.

In this paper, a novel risk-based, two-objective (technical and economical) optimal reactive Power dispatch method in a wind-integrated Power system is proposed which is more consistent with operational criteria.  The technical objective includes the minimization of the new voltage instability risk index. The economical objective includes cost minimization of reactive Power generation and active Power loss. The proposed voltage instability risk employs a hybrid possibilistic (Delphi-Fuzzy)-probabilistic approach that takes into consideration the operator’s experience, the wind speed and demand forecast uncertainties when quantifying the risk index. The decision variables are the reactive Power resources of the system. To solve the problem, the modified multi-objective particle swarm optimization algorithm with sine and cosine acceleration coefficients is utilized. The method is implemented on the modified IEEE 30-bus system. The proposed method is compared with those in the previously published literature, and the results confirm that the proposed risk index is better at estimating the voltage instability risk of the system, especially in cases with severe impact and low probability. In addition, according to the simulation results compared to typical security-based planning, the proposed risk-based planning may increase the security and economy of the system due to better utilization of system resources.

In this paper, the efficiency and reliability of the two- stage AC/DC Power electronic converter has been optimized for use in aircraft systems. The optimization is done using multi- objective genetic algorithm (NSGA- II), in order to minimize the objective function. The objective function variables are efficiency and reliability. Markov model is used to evaluate reliability, in which short circuit and open circuit faults are considered for circuit elements. Also, the failure rate of circuit elements using the equations of the military standard (MIL- HDBK- 217), has been calculated. For optimization, The value of inductances and capacitors, the switching frequency of each stage, the transformer turn ratio and the DC link voltage are determined as the input of the objective function, and then sensitivity analysis is performed to eliminate any parameters that are not sensitive to the objective function.Then NSGA- II algorithm parameters including iteration count, population, mutation and crossover probabilities are defined to calculate circuit parameters and reliability evaluation is done in form of mean time to failure (MTTF) considering efficiency parameter. The results indicate that the converter has improved reliability while maintaining high efficiency.

Today, due to the development of renewable energy sources, the global energy crisis, issues related to environmental pollution and international restrictions, the use of solar energy along with energy storage systems on ships has attracted much attention. has done. However, in the electrical system of ships, there is a lot of sensitive equipment that can be very sensitive to voltage disturbances, and if the disturbances of the voltage are greater than the weight of the tank, it is too heavy. Voltage disturbances are mainly caused by a decrease in voltage, an increase in voltage, a decrease in voltage, a decrease in the voltage on the floor and a half. امی Dynamic voltage measurement DVR is one of the most effective and common tools that can be used to reduce voltage disturbances. In this paper, a hybrid system consisting of a synchronous generator and a solar cell with the presence of Dynamic voltage recovery is presented for use in the ship. The simulation results obtained by Matlab / Simulink software also show the presence of Dynamic voltage recovery. Reduce disturbances.