Volume 20, Issue 1 -

The article presents the Hybrid Real-Time Dispatcher Training Simulator (HRTDTS). The main advantages of this simulator are the adequate simulation of a single spectrum of processes in the object for training – any real electric power system (EPS), as well as the real-time control of the equipment circuit-mode states in modes of the EPS operation. This is achieved by the HRTDTS development within the concept of hybrid simulation, which allows to surpass the modern widely-used simulators based purely on numerical simulation, which do not comprehensively reproduce processes in the EPS and limit the training of certain dispatchers skills. The dispatcher simulator structure and the developed specialized HRTDTS software are demonstrated. The developed dynamic dashboards for monitoring and operating, implementing the circuit-mode states visualization of the equipment or the EPS districts that correspond to specific objects for training, are presented. The special panels that display extended information about the processes in the EPS are also shown in the article. The comparison of simulation results with the data, obtained via RTDS, for the HRTDTS validation was carried out. The practical emergency scenario for the training of dispatching personnel, including the assignment of an emergency situation and the actions of dispatchers to eliminate it, was created for testing and demonstration of the HRTDTS capabilities.

In order to solve the problem of foundation settlement monitoring, this paper presents a monitoring program of substation foundation settlement, which is based on the distributed optical sensing technology. The composition of the hardware monitoring system and the wiring scheme of stress optical cables were described. The results of simulation experiment showed that the Brillouin optical time domain analysis could well meet the precision requirements of substation settlement monitoring. Moreover, the temperature reference optical fibers should be laid for temperature compensation. This paper can provide the basis for further prevention of substation foundation settlement.

One of transient phenomena that lead to the false trip of the power transformer differential protection during the energization of a loaded power transformer is the ultra-saturation phenomenon. This paper presents, at first, a new algorithm for three-phase power transformer differential protection considering effect of the ultra-saturation phenomenon based on Discrete Wavelet Transform (DWT). To model the ultra-saturation phenomenon, the nonlinear characteristic of the transformer core and the effect of the saturation of the current transformers are taken into account. It is assumed that the load of the transformer is a resistive and inductive load. In this algorithm, the ultra-saturation phenomenon, the external and internal faults of power transformer and the magnetic inrush current are simulated. To distinguish between these phenomena, appropriate criteria using DWT by the use of standard deviation of coefficients are presented. Also, one of the most important criteria for the digital relays is the time for making a decision. Thus, to determine the time of decision, the experimental results will be presented.

In this paper, a robust planning method of regional integrated energy system (IES) considering the uncertainty of cooling, heat and electrical loads on the demand side is submitted. First, the energy hub (EH) model of regional IES with Combined Cooling Heating and Power (CCHP), electric air-conditioning unit (EC) and gas boiler (GB) is established. Second, the uncertainty of load is described by the method of adjustable interval, and the robust planning model of regional IES is formed. Third, the robust programming model can be transformed into a convex mixed integer planning model, and then solved. Finally, the case study is carried out with a comprehensive area of Tianjin in China, the results are analyzed to verify the effectiveness of the proposed planning method.

Demand response (DR) programs have become powerful tools of the smart grids, which provide opportunities for the end-use consumers to participate actively in the energy management programs. This paper investigates impact of different DR strategies in a home-energy management system having consumer with regular load, electric vehicle (EV) and battery-energy storage system (BESS) in the home. The EV is considered as a special type of load, which can also work as an electricity generation source by discharging the power in vehicle-to-home mode during high price time. BESS and a small renewable energy source in form of rooftop photovoltaic panels give a significant contribution in the energy management of the system. As the main contribution to the literature, a mixed integer linear programming based model of home energy management system is formulated to minimize the daily cost of electricity consumption under the effect of different DR programs; such as real time price based DR program, incentive based DR program and peak power limiting DR program. Finally, total electricity prices are analysed in the case studies by including different preferences of the household consumer under mentioned DR programs. A total of 26.93 % electricity cost reduction is noticed with respect to base case, without peak limiting DR and 19.93 % electricity cost reduction is noticed with respect to base case, with peak limiting DR.

This paper investigates the performance of a radial system while installing a Distributed Generator (DG) in existing Distribution Network (DN). The investigation has been performed with various types of DG units for different topologies of the DN. The present work uses a Voltage Stability Index (VSI) for identifying the location for installing a DG in the DN. A multi-objective framework is proposed to evaluate the size of the DG to be installed by reducing power loss and deviation in bus voltage. Genetic Algorithm (GA) is used to optimize the size of DG. The proposed method has been tested with different types of DG units on standard systems (IEEE-33 bus and IEEE-69) with different radial topologies of DN.

Considering the operating pattern of battery charging and swapping station (BCSS) providing two power supply modes referring to battery charging mode and battery swapping mode at the same time, the power supply mode planning of electric vehicle (EV) participating in logistics distribution is conducive to decrease the operation costs. The primary contribution of this paper is to construct an optimization model with the objective of minimizing the overall cost of transportation cost and slow charging cost by considering the optimal driving route of EV, the selection of power supply mode and the slow discharging or charging management in the depot. The transportation cost is consisted of fast charging cost, battery swapping cost, battery life loss cost and vehicle loss cost. The secondary contribution of this paper is to improve a novel optimization algorithm called natural aggregation algorithm (NAA) as integer version to solve effectively the proposed model. Taking 33-node logistics distribution system as an example to carry out numerical simulation, the impacts of power supply mode planning on transportation cost and slow dis/charging cost are analyzed, the impacts of slow dis/charging strategy on the total cost are analyzed, and the effectiveness of proposed model in 13-node, 64-node, 112-node logistics distribution system are comparatively analyzed. The simulation results have demonstrated the feasibility and effectiveness of the proposed model and approach.

The search for alternative sources of energy, aimed at supplying the energy matrix, has shown a rapid increase in the use of wind energy worldwide. However, the interaction between wind farms and the electrical networks has shown itself to be an area of research interest. Among those phenomena that require evaluations by regulatory agencies, which in general aim at authorizing access to electric networks, emphasis is given to the following performance magnitudes: harmonic distortions, flicker, impacts on steady state voltages, transitory and dynamic performances, etc. The focus is here placed upon studies related to the estimation of individual and total harmonic distortions that are produced on the connection bus, these are frequently performed through use of computational resources. To this end, the studies are conducted on the basis of injecting individual harmonic current components produced by the generating units, which once adequately fixed, interact with the harmonic impedances determined by the composition of the internal network of the windfarm, along with the geometric locations that characterize the harmonic impedances of the connecting network. Therefore, such evaluations are performed based on equivalent Norton harmonics, which require, as a premise, the harmonic currents that are produced and injected. In this context, the present article is centered on specific issues linked to the qualitative and quantitative characterization of these harmonic currents, with emphasis on operational factors that exert influence on its orders and amplitudes. This work is conducted in order to clarify the origin and nature of the generated currents, the factors that influence such magnitudes, and finally, an evaluation of the theme through experimental studies performed for a laboratory installation aimed at emulating a full converter type of wind generator.

A method is proposed to modify the conventional load flow programme to accommodate large-scale Solar PhotoVoltaics (SPV) power plant with series power specifications. The programme facilitates easy handling of any number of SPV systems with standard control strategies such as pf- control and voltage- control, considering solar inverter’s power constraints. In this method, the non-linear equations related to SPV systems, located at multiple locations, are solved with the main load flow equations in an integrated fashion, considerably reducing the implementation task. This task is achieved by augmenting the inverter buses to the existing power system network in such a way that the changes required in the conventional programme are minimal. To show the effectiveness of the proposed method, it is compared with the alternate-iteration method popularly followed in the literature. The workability of the proposed method has been demonstrated by using a Single Machine Infinite Bus (SMIB) system and the IEEE14-bus power system with SPV systems. Various test cases pertaining to meteorological variables and control strategies are also presented.

This paper presents modelling and dynamic stability study of an interconnected system of renewable energy sources (RES) and grid. The objective of this system is to utilize RES for providing continuous power to a cluster of villages having fixed feed of power supply from the grid. The renewable energy sources considered in the interconnected system are wind and biogas. Therefore, dynamic models for doubly fed induction generator (DFIG) and squirrel cage induction generator (SCIG) based wind energy conversion system have been developed for the proposed interconnected system. The static synchronous compensator (STATCOM) has also been employed to stabilize system voltage as per the requirement while, synchronous generator-based biogas genset has been used for system frequency and voltage regulation. The behavior of the proposed system has been analyzed under various load and input wind power disturbances.

This paper presents an assortment study between the virtual inertia control (VIC)-based a new optimal PID controller, load frequency control (LFC), and the digital protection for an islanded microgrid (MG) taking into consideration the emerging level of renewable energy resources (RERs), which is a promising solution. However, the reduction in system inertia due to increasing the amount of RERs causes undesirable impact to MG dynamic stability, threatens the system security, and could lead to complete blackouts as well as damages to the system equipment. Therefore, maintaining the dynamic security in MGs is one of the important challenges, which considered in this paper using a specific design of a digital over/under frequency relay (OUFR) with coordination of the VIC to protect the MG against high-frequency variations. To prove the effectiveness of the proposed coordination strategy, it has been tested considering sudden load change, high integration of RERs. Moreover, the sensitivity analysis of the presented technique was examined by varying the inertia level of MG system. The results stated that the proposed coordination can effectively regulate the MG frequency and maintain the dynamic stability and security.

Type tests are essential to assess the short circuit withstand capabilities of transformer windings. The mechanical durability of power equipment are checked against the mechanical forces developed during making/breaking short circuit operations. These type tests are generally carried out in indoor transformer test laboratories. Testing of Power Transformer for size more than 200 MVA in 765/400 kV voltage class in an indoor laboratory is not economically feasible. Now a days, power transformer manufacturers are fabricating single phase auto- power transformers of size up to 630 megawatt volt ampere (MVA) rating. Type testing of these transformers in indoor laboratories is not feasible. In view of this, strong short circuit fault feeding capabilities of the national grids can be utilized for type testing of these power transformers in an online manner. However, this may affect the grid operation/control during weak grid operating conditions. Recently, National High Power Testing Laboratory is established for testing of power transformer upto of 630 MVA. This is a unique online transformer test facility for testing of 765/400/220/132 kV class power transformers. An offline simulation has been carried out in this article, to assess the impact of online type testing on the Indian National grid. In this article, an online testing scheme has been presented which enables the national grid operator to analysis the prevailing grid condition & subsequently to decide the safe rating of the power transformer for online testing. The simulated results are cross checked with field results and it is found that simulated results are close to actual field results. The concurrence of simulated and field results helped in successfully commissioning of the testing laboratory.