Power Factory Research Articles

Impact of Renewable Energy Sources as Co-generation Plant on Power System Network

This paper focuses on the power system evaluation due to integration of renewable energy sources like bagasse and biogas. The coal is only used when bagasse is not available. Two factor is taken for evaluation purpose like on season and off season scenario. The main objective of the work to supply surplus electricity to the national grid after fulfilling its own consumption. In this research a 6.3MW co-generation plant has been performed in Power Factory software for analyses. Simulation result shows load flow calculation, voltage deviation, total loss, external feed, active power and impact of reactive power, and required MVAR at two operation scenarios. The final result looks quite encouraging and this proposed co-generation system can be the framework to be developed for ameliorating energy crisis in Bangladesh.

Centralized coordination of emergency control and protection system using online outage sensitivity index

This paper determines the best locations for centralized load shedding considering the protection systems that can be monitored from transmission system to avoid cascading failures. The vulnerability of power system integrity is determined and ranked using online outage sensitivity index (OSI) considering ampacity of transmission lines, over excitation of generators and transformers, under frequency and under voltage protection relays and low voltage ride through capability of grid connected renewable energy sources. The power system elements are ranked based on the results of outage sensitivity index (OSI) to concentrate the load shedding as control action on areas containing most critical elements prone to outage. The efficiency of proposed multi objective approach is validated through numerical simulations of severe contingencies carried out in DigSilent Power Factory software on 39 bus IEEE standard test system.

A New Fault Location Method for Partial Coupling Double-Circuit Untransposed Transmission Line with Shared Tower and Different Voltages

This paper presents a new fault location method for partial coupling double-circuit untransposed transmission lines with shared tower and different voltages. The synchronized voltages and currents at each line terminal are needed to obtain the fault location. The proposed method is formulated based on theory of transmission lines and Taylor series expansion for distributed parameter line model. The mutual coupling between all phases and the untransposition of the line is considered to obtain accurate results. The faulted phases are recognized using Kirchhoff’s current law (KCL) and the locations of all fault types including inter-circuit faults can be determined. The power system is modeled on DIgSILENT Power Factory software, and the fault location calculations are implemented using MATLAB. The performance of the proposed method is checked under diverse values of fault types, fault resistances, and fault locations. The effect of synchrophasors errors, measurement errors, varying soil resistivity, errors in line parameters, and complex fault impedance is also verified. The simulation results prove that the proposed method achieves better performance for all test cases.

Preventive Security-Constrained DCOPF Formulation Using Power Transmission Distribution Factors and Line Outage Distribution Factors

This study proposes a very effective formulation to carry out the security-constrained direct current (DC)-based optimal power flow (OPF) problem using two linear factors: (i) the power transmission distribution factors (PTDF) and (ii) the line outage distribution factors (LODF). The security-constrained (SC) DCOPF problem has been reformulated using these linear distribution factors, and mainly the pre- and post-contingency constraints have been added into the optimization problem based on the active power unit generation (decision variables). The main advantage of this formulation is the reduction of decision variables as well as equality and inequality constraints. To validate the introduced formulation, several experiments have been conducted using MatPower, DIgSILENT Power Factory and Gurobi. Simulation results demonstrate both the feasibility to carry out the SCOPF problem and the potential applicability of the proposed formulation to medium and large-scale power systems.

Methodology to qualify marine electrical propulsion system architectures for platform supply vessels

Conventional diesel-electric propulsion systems in platform supply vessels (PSVs) use low-voltage AC (LVAC) supply-based architecture with multiple diesel-generators feeding busbars at 690 V, 60 Hz. The busbars distribute power to thruster motor drives via multi-pulse transformers and diode bridge rectifiers. Advancements in electrical power conversion and distribution technologies offer possibilities of AC or DC distribution at low/medium voltage (LV/MV) for reduced fuel consumption (FC), emissions, and equipment footprint. This study presents methodology to qualify propulsion system architecture for PSV application. Potential architectures, besides conventional one, are active front end (AFE) converter-based LVAC (690 V), MVAC (3.3 kV), LVDC (1000 V), and MVDC (5000 V). Performances of these architectures are assessed quantitatively based on FC, emissions, weight, volume, efficiency, and reliability. FC is estimated based on brake-specific FC data of diesel engine. NO x , SO 2 , and CO 2 emissions are assessed based on their emission factors. The weight, volume, and efficiency are estimated based on parameters of individual components. Reliability is assessed based on component failure data using DIgSILENT Power Factory. The architectures are ranked based on performance parameters using a Pugh matrix. The most suitable architecture for the target PSV is LVDC, followed by MVDC, LVAC with AFE, MVAC, and conventional LVAC.

Impacts of Photovoltaic Distributed Generation Location and Size on Distribution Power System Network

As the rapid development of photovoltaic (PV) technology in recent years with the growth of electricity demand, integration of photovoltaic distributed generation (PVDG) to the distribution system is emerging to fulfil the demand. There are benefits and drawbacks to the distribution system due to the penetration of PVDG. This paper discussed and investigated the impacts of PVDG location and size on distribution power systems. The medium voltage distribution network is connected to the grid with the load being supplied by PVDG. Load flow and short circuit calculation are analyzed by using DigSILENT Power Factory Software. Comparisons have been made between the typical distribution system and the distribution system with the penetration of PVDG. Impacts in which PVDG location and size integrates with distribution system are investigated with the results given from the load flow and short circuit analysis. The results indicate positive impacts on the system interconnected with PVDG such as improving voltage profile, reducing power losses, releasing transmission and distribution grid capacity. It also shows that optimal locations and sizes of DGs are needed to minimize the system’s power losses. On the other hand, it shows that PVDG interconnection to the system can cause reverse power flow at improper DG size and location and increases short circuit level.

Optimal overcurrent relay coordination in distribution network based on Lightning Flash Algorithm

PurposeDistribution network protection is a complicated problem and mal-operation of the protective relays due to false settings make the operation of the network unreliable. Besides, obtaining proper settings could be very complicated. This paper aims to discuss an innovative evolutionary Lightning Flash Algorithm (LFA) which is developed for solving the relay coordination problems in distribution networks. The proposed method is inspired from the movements of cloud to ground lightning strikes in a thunderstorm phenomenon. LFA is applied on three case study systems including ring, interconnected and radial distribution networks. The power flow analysis is performed in Digsilent Power Factory software; then the collected data are sent to MATLAB software for optimization process. The proposed algorithm provides optimum time multiplier setting and plug setting of all digital overcurrent relays in each system. The results are compared with other methods such as particle swarm optimization and genetic algorithm. The result comparisons demonstrate that the proposed LFA can successfully obtain proper relay settings in distribution networks with faster speed of convergence and lower total operation time of relays. Also, it shows the superiority and effectiveness of this method against other algorithms.Design/methodology/approachA novel LFA is designed based on the movements of cloud to ground lightning strikes in a thunderstorm. This method is used to optimally adjust the time multiplier setting and plug setting of the relays in distribution system to provide a proper coordination scheme.FindingsThe proposed algorithm was tested on three case study systems, and the results were compared with other methods. The results confirmed that the proposed method could optimally adjust the relay settings in the electric distribution system to provide a proper protection scheme.Practical implicationsThe practical implications can be conducted on distribution networks. The studies provided in this paper approve the practical application of the proposed method in providing proper relay protection in real power system.Originality/valueThis paper proposes a new evolutionary method derived from the movements of cloud to ground lightning strikes in thunderstorm. The proposed method can be used as an optimization toolbox to solve complex optimization problems in practical engineering systems.

Fault location algorithm for multi‐terminal mixed lines with shared tower and different voltage levels

This study presents a new fault location algorithm for multiple-circuit shared tower transmission lines with different voltages utilising synchronised measurements. The formulation of the proposed algorithm is based on overhead transmission lines theory and Taylor series expansion of distributed-parameter line model. The untransposition of the lines and the mutual coupling between the parallel lines are considered to achieve precise fault location. Kirchhoff's current law and fault location equation are used to identify the faulty section and obtain the location of all normal shunt faults and inter-circuit faults. The power system is simulated with DIgSILENT Power Factory software and all calculations are performed by MATLAB. Numerous fault cases are conducted to demonstrate the efficacy of the proposed algorithm considering different values of fault resistances, different fault locations and all fault types. In addition, the effects of synchrophasors errors, measurement errors and the soil resistivity variations are investigated. The results of simulation prove the efficacy of the proposed algorithm for all fault cases.

New fault location scheme for four-circuit untransposed transmission lines

This paper introduces a new fault location scheme for two-terminal four-circuit untransposed transmission line using synchronized measurements. The current phasors at both line terminals and the voltage phasor at only one terminal are needed to formulate the fault location equation. The proposed scheme is developed based on theory of transmission lines and expansion of Taylor series for the distributed line model parameters. The mutual coupling between all phases and the untransposition of the line are considered to obtain precise results. The faulty phases are determined using Kirchhoff’s current law (KCL) and all fault types including normal shunt and inter-circuit faults can be located. DIgSILENT Power Factory software is used to simulate the power system and the fault location calculations are carried out using MATLAB. The proposed scheme is investigated under different fault locations, fault inception angles, fault types, and fault resistances. The influence of soil resistivity variation, measurement and synchrophasors errors, errors in line parameters, various line lengths, non-linear time-varying arc resistance, and complex fault impedance is also investigated. The simulation results confirm the validity of the fault location scheme for all test cases.

A Multi-objective Approach for Optimized Monitoring of Voltage Sags in Distribution Systems

Voltage sags are among the most relevant power quality disturbances. Furthermore, they also have high occurrence rates. Their stochastic nature makes monitoring difficult and causes significant losses to power utilities and customers. This paper presents an approach to overcome the problem of allocating power quality monitors. To do so, our approach accounts for topological coverage, unmonitored voltage sags, and the total cost of required equipment. We used NSGA-II to build our approach due to its efficiency in dealing with combinatorial problems. We also used the Monte Carlo simulation method to model the time series in our approach due to the random nature of power quality disturbances. To evaluate our approach, we simulated the IEEE 13-, 34- and 37-bus distribution systems using the DigSILENT Power Factory 15.1 software. The evaluation results show that our approach supported cost reduction associated with the installation of power quality monitors, both in terms of identifying adequate number and position of the performance monitors.

Improving Adaptive Protection to Reduce Sensitivity to Uncertainties Which Affect Protection Coordination of Microgrids

Uncertainties in microgrid topology, protection system, and communication links involve accidental variables that affect the protection coordination of a microgrid. To resolve this issue, a method is proposed that uses a decision tree after each fault to ensure a robust protection coordination. The decision tree creates an optimal composition of strategies, such that for each unsuccessful strategy, the best possible strategy is substituted according to a number of uncertainty indices. The indices considered in this work include successfulness probability of strategies in clearing faults and the amount of loads outages caused by implementing these strategies. The probability of successfulness of strategies is considered to correct operation of circuit breakers and communication links involved in each strategy. The proposed method enables adaptive protection to decide according to microgrid topology and the probability of correct operation of protection system and communication links. In addition, it avoids saving too many offline decisions. The performance of the proposed method is tested on a sample microgrid in DIgSILENT Power Factory software, where the results of various case studies will be reported.

Impact of replacing thermal power plants by renewable energy on the power system

The Egyptian Electricity Holding Company (EEHC) has paid great attention to renewable energy sources; wind power (WP) and photovoltaic (PV). The EEHC Strategy aims at increasing the proportion of power totally generated from renewable energy sources (RES) to 20% by 2022. With increasing such amount of RES in the Egyptian electricity system, some of the on-line thermal power plants will be shut down and replaced by WP and PV. Thus the thermal reserve will be reduced making the available online thermal power plants fewer to share the regulation burden. The power system inertia will be reduced, the frequency deviation will be greater after system disturbance and more oscillation will occur. Therefore, this paper studies the impacts of increasing the renewable energy sources on the frequency control of the Egyptian power system by investigating different scenarios of increasing the RES to 20% after occurring sudden variations in generation. Also the impact of RES on environmental improvement is presented by calculating the expected annual CO2 emission reductions (ER), certified emission reduction (CER) and the amount of fuel saving. The model was created by using DIgSILENT power factory software.

Voltage Analysis Improvement of 150 kV Transmission Subsystem Using Static Synchronous Compensator (STATCOM)

In this research, testing improvements to the distribution voltage electricity at 150 kV transmission subsystem Bandung Selatan and New Ujungberung using Flexible AC Transmission System (FACTS) technology. One of them is by doing the control of active and reactive power through the power electronics equipment Static Synchronous Compensator (STATCOM). The subsystem is tested because it has a voltage profile are relatively less well when based on the IEEE / ANSI C.84.1 (142.5 - 157.5 kV). This study was conducted by analyzing the Newton-Raphson power flow on the simulator DigSilent Power Factory 15 to determine the profile of the voltage (V) on the system. Bus which has the lowest voltage to be a reference in the installation of STATCOM. From this research is known that the voltage on the conditions of the existing bus 28, as many as 21-23 still below standard buses (142.5 kV), after the installation is done using STATCOM, voltage on the buses improved by increasing the number of tracks that follow the standard / is in the range 142.5 kV -157.5 kV as many as 23-27 buses or 78.6% - 96%, with the optimum mounting on a bus Rancaekek STATCOM II with a capacity of 300 MVA.

A Decision-Tree Scheme for Responding to Uncertainties in Microgrid Protection Coordination

In addition to the dynamic nature of microgrids, uncertainty in the proper operation of protection system and communication links are other challenges affecting the protection coordination of these networks. Therefore, in this paper, a new protection coordination plan based on decision tree for considering uncertainties in the topology of microgrid, protection system, and communication links is presented. The proposed method allows the adaptive protection to make global decisions and adopt the best strategy to clear faults depending on considered uncertainties. Since circuit breakers are the most prone to failure equipment in the protection system due to fault-caused stress, this paper models uncertainty in the protection system with uncertainty in the performance of circuit breakers. In order to consider uncertainty in circuit breakers and communication links, their probability of correct operation are not considered fixed but variable, respectively, proportional to the fault current flowing through the circuit breakers and the latency of communication links. The proposed plan was tested on a sample microgrid in DIgSILENT Power Factory. Results prove that using the proposed method, adaptive protection can establish an optimal sequence of strategies so that with the failure of each strategy, the best backup strategy is replaced given the uncertainties.

Optimal Allocation of Multi-DG on Distribution System Reliability and Power Losses Using Differential Evolution Algorithm

The paper proposes the effects of multi-distributed generators (multi-DGs), which is integrated into the distribution system in terms of reliability indices and power losses. The distributed generators (DGs) under the study are connected to the distribution system at 22 kV of Thanyaburi substation on the Provincial Electricity Authority (PEA), which is a part of distribution system in Thailand. Multi-objective functions are considered the effects of multi-DG to improve system reliability and power losses. Moreover, this paper has proposed to determine the system average interruption frequency index (SAIFI), the system average interruption duration index (SAIDI) and the expected interruption cost (ECOST) are evaluate as reliability indices and determine active power loss (Ploss) and reactive power loss (Qloss) of power losses in distribution system. The optimal allocation of multi-distributed generators on distribution system reliability and power losses using Differential Evolution algorithm in MATLAB calculated and investigated in DIgSILENT Power Factory program. Aggregated results can be concluded by focuses on the placement and sizing of multi-DG, which are important factors that impacting the reliability indices and power losses.

Energy management system for stable operation of isolated microgrid

This study proposes an energy management system (EMS) for stable operation of isolated microgrid which is composed of diesel generators, wind turbines, photovoltaic generation systems and battery energy storage systems (BESS). In the EMS, a power dispatch control is proposed in order to minimise diesel operation. There is also a state-of-charge (SOC) control to allow continuous use of the BESS. By dispatching the scheduled power of the diesel generators, the SOC can be regulated within its limits. A simulation model for isolated microgrid was developed using DIgSILENT Power Factory® software. To verify the performance of the proposed EMS, case studies are performed using practical data of Dukjuk Island in Korea.

The Hydrogen Production System in Wind Power Micro Grid Modeling and the Simulation on Its Power Property

The fluctuation of wind power may easily cause the great impact on the grid while it was integrated in the grid in large scale, and resulted in the generally existed phenomenon of abandoned wind power and power brownouts accordingly. Aiming to such problem the academic circles have proposed the method of hydrogen production to consume the excessive wind power. In this paper, with the consideration of the power supply scheme for micro grid, it aims to enable the wind power better providing power for hydrogen production, and designs its structure according to the working principles of each module, and completes the system modeling of such micro grid based on Dig SILENT Power Factory software and carries out the flow analysis on such model and simulation of power control model, it proves that this system can be run stably theoretically.

Controlled Operation of the Islanded Portion of the International Council on Large Electric Systems (CIGRE) Low Voltage Distribution Network

In islanding, a portion of the power network, comprised of the loads and distributed generation (DG) units, is isolated from the rest of the power grid and forms a micro grid (MG). In this condition, it becomes essential for the islanded MG to operate in a stable and controlled manner by providing ancillary services. When the MG is cut off from the main grid, the islanding must be detected by the DG units. In this condition it is essential that one of the controllers should be switched to the voltage-frequency (VF) control mode. In islanding, the network loses it slack reference and this reference is established by a VF controller. The voltage and the frequency of the islanded MG deviate when disconnected from the transmission grid and these deviations are caused by the load-generation imbalance. The voltage and the frequency of the islanded MG can be restored to the permissible limits if the desired/exceeded amount of active and reactive power is injected/absorbed by the locally available sources in islanded MG. This paper proposes a control strategy which can compensate the voltage and the frequency deviations in the islanded portion of the International Council on Large Electric Systems (CIGRE) low voltage distribution network by using advanced power electronics devices such as STATCOMs) for Photovoltaic (PV) Units and Battery Energy Storage Systems (BESS) STATCOMs (for battery units). The selection of the VF controller for the most suitable DG unit of this test network is also presented in this paper, and the effectiveness of the controllers is verified by presenting simulation results using DIgSILENT (DIgSILENT GmbH, Gomaringen, Germany) power factory software version 15.0.

Analysis on Grid-connection Characteristics of Wind/Photovoltaic/Energy Storage Hybrid Station

Grid-connection characteristics of renewable energy, such as wind farm (WF) and PV plants often have the negative influence on the security and stability of power system. To smooth the active power, energy storage (ES) system was presented. The model presented of wind/photovoltaic/energy storage (W/PV/ES) hybrid station was simulated, and the grid-connection characteristics of W/PV/ES hybrid station were analyzed in Dig SILENT Power Factory. Simulation results show that it is positive and effective for ES to smooth the output fluctuation, and to improve the controllability of active power. Moreover, the electric power quality can be improved and the capacity of low voltage ride through (LVRT) can be raised for renewable energy station.

Implementation of a Generic Type I Wind Turbine Generator for Power System Stability Studies

According to the International Electrotechnical Commission (IEC), the standardization and modelling of generic Wind Turbine Generators (WTG) is a key fact which allows the co-operation of international organizations in the electrical field. Thus, according to the IEC 61400-27-1, the generic Type 1 WTG model has been implemented and simulated in DIgSILENT PowerFactory (PF). In fact, PF is the preferred software tool for some of the European network operators. The process of structuring and construction of the different WTG components within PF are conveniently described in this paper. In order to correctly simulate the generic IEC WTG model in PF, aerodynamic and mechanical systems are also required. For this reason, the Dynamic Simulation Language (DSL) tool within PF has been used for modelling these non-electrical components. Moreover, this language allows the dynamic modelling of linear and non-linear systems. Finally, once all the WTG components have been defined, normal and fault conditions have been analyzed in order to study the WTG dynamic response.