Devices In Power Systems Research Articles

Operation of synchronous generator LOE protection in the presence of shunt-FACTS

This paper deals with the impact of shunt-FACTS devices on the synchronous generator loss of excitation (LOE) protection. Considered shunt-FACTS devices in this paper include the static VAR compensator (SVC) and static synchronous compensator (STATCOM). The SVC has been modeled by thyristor switched capacitor (TSC) and thyristor controlled reactor (TCR) branches. Also, 48-pulsed converter is used to model STATCOM. The LOE relay considered in this paper is a negative offset mho distance relay containing two zones. It has been shown that injected reactive power of by shunt-FACTS devices prevents from the generator voltage drop during LOE, which causes the operation of LOE relay to be delayed. It has been also shown that when an incomplete LOE occurs, the presence of shunt-FACTS devices leads to under-reach of the relay. In this paper, various operational conditions of the power system and shunt-FACTS devices have been surveyed to authenticate the results.

Review of the Relationship between Harmonic and Parallel Capacitor Fault

The parallel capacitors are the most important reactive power compensation devices in power system, while the power system harmonic pollution is becoming increasingly serious in recent years, the accident that caused capacitors fault and damage by overload harmonic always happened. Based on this background and summary of the existing research results, thermal effect and performance index of capacitors are introduced, and analyzed the mechanism of interaction between harmonic and capacitor, then the effect and harm of running capacitor under harmonic conditions are elaborated, finally summarized the feasible measures for harmonic suppression and protection of capacitor devices.

Research on Gas Gush Smoke Camouflage Device for Transport Vehicle

Transport vehicle gas gush Smoke camouflage device, By use of its own power system and storage devices, Will be made in advance the size of the different, structure, function of polystyrene particles blown apart, Thus formed around the top of the vehicle and polystyrene particles as the main ingredients of camouflage a Smoke, To cover vehicles and interference against the infrared guidance, the purpose of the millimeter wave radar guidance weapon attacks.

Study on Resistance and Energy Deposition of Spark Channel Under the Oscillatory Current Pulse

In the use of spark gaps as switching devices in pulsed power systems, spark resistance is a crucial factor influencing the voltage rise time and the efficiency of energy delivered to the load. However, current oscillations make it difficult to accurately measure the spark resistance. Therefore, we present a spectrographic method to measure the spark radius and the conductivity of spark channel according to its emission spectrums. A series of experiments has been carried out to investigate the time-dependent properties of spark resistance under oscillatory damped current pulses. The current and voltage waveforms have been recorded to calculate the energy deposited in the spark channel. Furthermore, the influences of gas pressure and gap length on spark resistance and the deposited energy have been discussed. The results indicate that lower resistance, and energy deposition is obtained with shorter gap lengths operating at higher pressures.

Proposed Design for a Tunable Inductive Shield-Type SFCL

Superconducting fault current limiters (SFCLs) offer a good solution for the increased level of short circuits in power systems. Inductive shield-type SFCLs are one of the most promising categories of the SFCLs. A design has been proposed for a tunable fault current limiter, which has the capability to vary the level of current limitation via varying some control parameters. This increases the utilization flexibility of the SFCL and may result in economic gains. Regarding the ever-growing short-circuit level in the power systems that may demand upgrade or replacement of protection devices, if SFCLs are installed with the proposed structure, several current limitation levels may be available and selected due to the short-circuit level of the system and the nominal rating of different power system devices. The proposed design is verified calculating theoretically the through current of the SFCL and studying the impact of different control parameters on it. Furthermore, a prototype SFCL has been fabricated and has shown the desirable tunable current limitation characteristics.

Power System Loadability Maximization by Optimal Placement of Multiple-Type FACTS Devices Using PSO Based GUI

This paper presents a graphical user interface (GUI) uses Particle Swarm Optimization (PSO), which is used to find the optimal locations and sizing parameters of multi type Flexible AC transmission systems (FACTS) devices in complex power systems. The GUI toolbox, offers user to choose a power system network, PSO settings and the type and number of FACTS devices for the selected network. In this paper, three different FACTS devices are implemented: SVC, TCSC and TCPST. FACTS devices are used to increase the system loadability, by reducing power flow on overloaded lines, transmission line losses, improving system stability and security. With this can make the transmission system more energy-efficient. PSO used here for optimally allocating and sizing the multiple type FACTS in a standardized power network (IEEE 30 bus system) in order to improve voltage profile, minimizing power system total losses and maximizing system loadability with respect to the size of FACTS.

Multi-objective adaptive clonal selection algorithm for solving optimal power flow considering multi-type FACTS devices and load uncertainty

This paper presents a solution to multi-objective optimal power flow (MOOPF) problem using an adaptive clonal selection algorithm (ACSA) to minimise generation cost, transmission loss and voltage stability index (L-index) in the presence of multi-type FACTS devices in power systems. The proposed approach utilizes clonal selection principle and evolutionary concept which performs cloning of antibodies followed by hyper maturation. In this algorithm, a non-dominated sorting and crowding distance have been used to find and manage Pareto optimal front. Various voltage source converter (VSC) based multi-type FACTS devices such as UPFC, IPFC and GUPFC are considered and incorporated as power injection models in multi-objective optimisation problem formulation. The proposed multi-objective adaptive clonal selection algorithm (MOACSA) has been tested on standard IEEE 30-bus test system with FACTS devices. The results obtained from the proposed MOACSA approach are compared with implementation of standard algorithms namely NSGA-II, MOPSO and MODE.

Three Phase Power Flow Incorporating Static Var Compensator

Application of Flexible AC Transmission Systems (FACTS) devices in a power system is a promising and more efficient way for the transfer and control of bulk amount of power. One of the problems encountered in power-systems operation is the generation of unbalanced voltages and currents in the presence of long transmission lines with few or no transpositions. This includes possible unbalances arising in source and load conditions, or indeed any items of plant such as shunt and series reactors. To improve or investigate these unbalance effects in any detail, a 3-phase load-flow solution that allows representation of all possible unbalances as they exist in the power-systems network without making any assumptions is essential. This paper deals with the three phase power flow incorporating Static Var Compensator (SVC). Here SVC is modeled using variable reactance modeling technique and incorporated into the single phase and three phase load flow. Newton Raphson power flow algorithm is adopted here. The performance of SVC to control the power flow and regulating voltage in the network is discussed. The performance analysis is carried out for 4 case studies namely single phase power flow, single phase power flow with SVC, three phase power flow and three phase power flow with SVC. The change in power flow and losses due to the unbalanced load condition in the three phases in illustrated. The studies are carried out in a standard 5 bus test system. Keywords: Three Phase Power flow, Static Var Compensator, Unbalanced system, Negative sequence components, Zero sequence components.

Optimal allocation of multi-type FACTS devices in power systems based on power flow entropy

Flexible AC transmission systems (FACTS) devices can effectively optimize the distribution of power flow. Power flow entropy can be applied as a measure of load distribution. In this paper, a method is proposed to optimize the distribution of power flow with the coordination of multi-type FACTS devices and establishes the corresponding mathematical models. The modified group searcher optimization (GSO) algorithm is proposed, in which the angle search is combined with chaotic search model to avoid jumping into local optimization. Compared with the different optimal allocation of multi-FACTS devices, the optimal allocation of multi-FACTS devices is achieved under the economic constraints. The locations obtained by this method can achieve the purpose of balancing power flow and enhancing the system performances. The simulations are demonstrated in an IEEE 118-bus power system with two classical types of FACTS, namely static var compensator (SVC) and thyristor controlled series Compensator (TCSC). The simulation results show that the proposed method is feasible and effective.

Influence of Winding Accuracy on Magnetic Field Distribution in YBCO Pancake Coil for Cyclotron Application

In recent years, YBCO high-temperature superconducting (HTS) tapes have been expected to be applied to devices in power systems or in other industrial applications, owing to their rapidly improving quality and productivity. Our objective is to develop an HTS cyclotron with a compact body, high efficiency of output power, and high performance in heavy particle radiotherapy. In such an application, extremely high precision is required in the range 0.01% to 0.1% of magnetic field, both spatially and temporally. An isochronous field along with an azimuthally varying field is generated by an air-core pancake coil system during construction. Therefore, developing a technology for extremely high coil-winding accuracy is very important. In this study, we constructed an experimental model of a YBCO pancake coil using a high-precision coil winding machine. Then, the winding error in the radial and axial directions was experimentally evaluated using a pair of laser displacement meters and a surface roughness tester. We also developed a numerical simulation model to analyze the influence of winding error on the magnetic field distribution. The relationship between the winding error and the magnetic field of the meter-class YBCO coil assuming a real system was also evaluated by numerical simulation.

Power Oscillation Damping Improvement by Adding Multiple Wind Farms to Wide-Area Coordinating Controls

This paper examines the feasibility of coordinating variable-speed wind farms with other power system devices, such as flexible ac transmission systems and synchronous generators, to damp low-frequency oscillations. For this purpose, an observer-based state-feedback approach is used to build a power oscillation damping (POD) controller, implemented through coordinated actions of multiple control devices, and able to manage several measurement channels. The wide-area POD controller also presents a time-delay compensation stage to mitigate adverse effects of latency involved in wide-area communication systems. Several practical issues are discussed and analyzed, such as measurement and control selection, model-order reduction, transmission time-delay compensation, impact of the POD control on wind farms, and robustness aspects. The control performance is evaluated and compared with other control schemes using eigenvalue analyses and nonlinear time-domain simulations over a wide range of operating conditions, for example, severe system faults, N - 1 outage contingencies, load/generation shedding, and line tripping.

Continuous Monitoring of Smart Grid Devices Through Multi Protocol Label Switching

Data refreshment rate of a present power system is relatively slow and in some cases this slow refreshment rate may not be capable of providing information about dynamic state of power system devices. The use of multi protocol label switching based technique is one option to overcome this problem. A cost effective and simpler detection device is needed for condition monitoring and integrating the sensor signals into the smart grid monitoring system. Remote and on-line monitoring of ultra wide band partial discharge signal in a switch-yard is a new concept in smart grid technology that will help avoid damage of switchyard devices. It is possible to convert the radio frequency partial discharge signal into an equivalent milli-volt or milli-ampere output for remote or centralized monitoring of switchyard devices. Multi Protocol Label Switching based data transfer rate is faster than the conventional data transfer system of a power grid. In this paper a new and technically better method of on-line radio frequency partial discharge monitoring from a remote smart grid control room through multi protocol label switching is discussed.

Experimental Investigations and Ageing Studies on Effects of Insulating Barriers in Transformer Oil during High Frequency High Voltage Transients in Inhomogeneous Field

Insulating barriers utilized in complex high voltage insulation systems has been exploited widely by manufacturers of power apparatus. Barriers have found utility in a variety of power apparatus for protection against direct lightning strokes, as an interface at the boundaries of composite insulation materials etc. Though investigations have been carried out by researchers on the breakdown characteristics, barrier position in the gap, influence of space charge etc these characteristics have been analyzed based on aspects pertinent to classical testing procedures only. Advent of high speed switching devices in power systems provides avenues to investigate the effect of insulation performance due to High Frequency High Voltage (HFHV) also. Further, uncharacteristic failures in oil filled distribution transformers have been reported indicated fast transients as the major cause for failures which was not revealed during classical laboratory testing. This research focuses on the influence and effects of solid insulating barriers placed in transformer oil due to HFHV in inhomogeneous fields. Test cell arrangement has been fabricated for carrying out experimental investigations to adhere international standards. Exhaustive experimentation has been performed to infer the influence of the position of barrier, nature of field and breakdown voltage, erosion characteristics of the barrier at an appropriate range of frequencies. A detailed comparison between HFHV and classical power frequency voltage has been carried out. The nature of ionization at the barrier interface and the subsequent increase in the breakdown voltage as explained by Double Electric Layer (DEL) theory has been cross validated. In addition, a study has also been carried out to assess and characterize the ageing of oil based on Dissolved Gas Analysis (DGA) analysis using Weibull distribution.

Reactive Power Optimization with SVC & TCSC using Genetic Algorithm

In this paper Genetic Algorithm (GA) is used as an evolutionary tecthniques for the optimal placement of flexible AC transmission systems (FACTS) devices in an interconnected power system. Here two types of FACTS devices has been discussed nemely, Thyristor Controlled Series Capacitor (TCSC) and Static Var Compensator (SVC) for the economic operation and to reduce the transmission loss. Reactively loading of the system is taken from base to 200% of base loading and the system performance is observed without and with FACTS devices. Optimal placement of FACTS devices in the system is determined by calculating active and reactive power flow in lines. FACTS devices along with reactive generation of generators and transformer tap setting are used for the power transfer capacity using GA. The proposed approach is applied on IEEE 14 and IEEE 30-bus test systems. Finally the effectiveness of the proposed GA based method of placement of FACTS devices is established by comparing the results with another standard method of optimization like Particle Swarm Optimization (PSO) technique.

A Study on AT and C Losses Control in Power System Using DFACTS Devices

In this paper, we have discussed about the study of Distributed Flexible AC Transmission System (D- FACTS) devices in power system by controlling AT&C losses. D-FACTS devices offer many potential benefits to power system operations. Modern power systems are continuously being expanded and upgraded to cater the need of ever growing power demand. This is a review paper to analyze the current trends in FACTS and D- FACTS to improve the performance of existing power system performance. D-FACTS devices are applied to minimizing real power losses and controlling system voltages after they have become too high. It contains work which has been carried out by various researchers in the field of FACTS and D-FACTS.

A PSO-DP Based Method to Determination of the Optimal Number, Location, and Size of FACTS Devices in Power Systems

The presence of reactive component of current in transmission lines causes adverse impact on the network, including power losses, reduction of line capacity, and voltage drop. These ad ...

A hybrid algorithm to tune power oscillation dampers for FACTS devices in power systems

The interaction between electrical and mechanical torques in the synchronous machines connected to bulk power transmission systems gives rise to electromechanical oscillations which, depending on the operating conditions and type of disturbance, may be poorly damped or even unstable. Recently, a combination of power system stabilizers (PSSs) and power electronic devices known as FACTS (flexible alternating current transmission systems) has been recognized as one of the most effective alternatives to deal with the problem. Tuning such a combination of controllers, however, is a challenging task even for a very skilled engineer, due to the large number of parameters to be adjusted under several operating conditions. This paper proposes a hybrid method, based on a combination of evolutionary computation (performing a global search) and optimization techniques (performing a local search) that is capable of adequately tuning these controllers, in a fast and reliable manner, with minimum intervention from the human designer. The results show that the proposed approach provides fast, reliable and robust tuning of PSSs and FACTS devices for a problem in which both local and inter-area modes are targeted.

Comparative study of GA & DE algorithm for the economic operation of a power system using FACTS devices

Abstract The problem of improving the voltage profile and reducing power loss in electrical networks must be solved in an optimal manner. This paper deals with comparative study of Genetic Algorithm (GA) and Differential Evolution (DE) based algorithm for the optimal allocation of multiple FACTS (Flexible AC Transmission System) devices in an interconnected power system for the economic operation as well as to enhance loadability of lines. Proper placement of FACTS devices like Static VAr Compensator (SVC), Thyristor Controlled Switched Capacitor (TCSC) and controlling reactive generations of the generators and transformer tap settings simultaneously improves the system performance greatly using the proposed approach. These GA & DE based methods are applied on standard IEEE 30 bus system. The system is reactively loaded starting from base to 200% of base load. FACTS devices are installed in the different locations of the power system and system performance is observed with and without FACTS devices. First, the locations, where the FACTS devices to be placed is determined by calculating active and reactive power flows in the lines. GA and DE based algorithm is then applied to find the amount of magnitudes of the FACTS devices. Finally the comparison between these two techniques for the placement of FACTS devices are presented.

Solution of multiple UPFC placement problems using Gravitational Search Algorithm

Optimal power flow is one of the key tasks to be performed in the complicated operation and planning of a power system. The Unified Power Flow Controller (UPFC) is a powerful power electronics device capable of providing complex control of power systems. In this paper, Gravitational Search Algorithm (GSA) is applied to solve optimal power flow problem in the presence of multiple UPFC devices. The performance of GSA is compared for accuracy and convergence characteristics with heuristic search techniques like Biogeography-Based Optimization (BBO), Stud Genetic Algorithm (StudGA), Genetic Algorithm (GA), Ant Colony Optimization (ACO), Probability-Based Incremental Learning (PBIL), on the different cases of standard test systems and real life power system. The tabulated results reveal that GSA has a great capability in handling power system planning and operational problems and to provide good quality solution quickly. The effort of optimal placement of multiple UPFC devices in power system cannot be commonly found in technical literature.

OPTIMALLY LOCATED SVC FOR TRANSMISSION OF RENEWABLE ENERGY IN LARGE POWER SYSTEM

Shunt FACTS devices provide the possibility to control voltages and therefore to improve the security of the system. In order to use this possibility, the optimal location and the set values of the FACTS controllers have to be selected correctly. The singular analysis of the power system Jacobian matrix are applied to identify the optimal location of shunt FACTS devices in large power systems. Furthermore the application of Optimal Power Flow control is a possible method for choosing set values. In this paper a sensitivity index for the detection of sensor nodes is defined. Sensitivity analysis is used to determine the area on which the FACTS device has significant influence. And then only this limited area is included in the Optimal Power Flow control, because it is very difficult to include the entire system into the optimization process. Matlab code is written to find the optimal location of Shunt Facts device i.e., SVC. Furthermore the objective function of Optimal Power Flow control is analyzed. This function consists of three components. A certain type of FACTS is not able to influence all these components.