Laboratory Scale Power System Research Articles

A Fractional Order Power System Stabilizer Applied on a Small-Scale Generation System

In this paper, a Fractional Order Power System controller (FOPSS) is designed, and its performance and robustness are experimentally evaluated by tests in a 10 kVA laboratory scale power system. The FOPSS design methodology is based on the tuning of an additional design variable, namely the fractional order of the controller transfer function. This design variable is tuned aiming to obtain a tradeoff between satisfactory damping of dominant oscillating mode and improved closed-loop system robustness. For controller synthesis, transfer function models were estimated from data collected at selected operating points and subsequently applied for the controller design and for obtaining upper bounds estimates on the operating-point depends on plant uncertainties. The experimental results show that the FOPPS was able to obtain a robust performance for the considered set of the power system operating conditions.

Simple electric utility platform: A hardware/software solution for operating emergent microgrids

Along with the technical feasibility of microgrids, the importance of supervisory communications, computing, and control (CCC) systems that are necessary to operate a microgrid in a stable and economically feasible manner have been firmly established in the literature. While several investigators have proposed and demonstrated algorithms and applications of CCC, the functional entities and responsibility centers for realizing CCC within microgrids in the context of multiple independent customers and distribution system entities have not been situated and/or studied. In this context, the term emergent microgrid may be used to define an electrical network that consists of local generation, loads, and storage. Such a grid has the potential to be clustered as a microgrid, but does not have all the CCC features to become a full-fledged microgrid. In this paper, a simple electric utility platform (SEUP) that is an end-to-end solution with all the hardware/software interfaces and components necessary for augmenting emergent microgrids with CCC into full-fledged microgrids is presented. SEUP abstracts the details of sensing and CCC for the microgrid developers, installers, operators and end-users to provide a seamless system. SEUP is distinctive from other CCC platforms in that it is entirely based on publicly available infrastructure resources (wireless cellular networks, internet and cloud computing) without any intellectual property restrictions. The paper introduces the functional roles, main architecture, components and security features of SEUP along with the results from a sample application case of a laboratory-scale power system.

Current Limiting and Recovery Characteristics Under Load of Transformer Type SFCL with Rewound Structure Using BSCCO Wire in Model Power System

Abstract We have proposed new design of a transformer type SFCL with primary and secondary superconducting coils which has rewound structure. For not so large fault current, the proposed SFCL limits the current by the inductive component by the normal transition of the flux shielding coil (secondary), and for larger fault current, it can give the resistive component additively by the normal transition of the primary coil. The recovery characteristics under load condition and repetitive limiting operation were experimentally investigated in a laboratory scale power system. The SFCL limited twice repetitive faults current and recovered quickly under load condition.

Current Limiting Experiment of Transformer Type Superconducting Fault Current Limiter With Rewound Structure Using BSCCO Wire in Small Model Power System

Superconducting fault current limiters (SFCLs) are expected to improve the reliability and stability of power systems. We have proposed new design of a transformer type SFCL whose primary and secondary superconducting coil has rewound structure. The fundamental characteristics of the proposed SFCL were investigated using a small model designed and made with BSCCO wire. This paper describes on the power system characteristics of the proposed SFCL with rewound structure. The basic experiments were carried out by use of the model SFCL in a laboratory scale power system (one-machine and infinite bus system). It was confirmed that the proposed SFCL successfully limited the fault current and suppressed the voltage drop of the generator and recovered quickly even in repetitive limiting operation.

同期発電機過渡時における制動巻線の効果の実機評価

This paper describes the results of an experimental investigation on the effects of the damper winding of a four-pole synchronous generator at a synchronous generator transient. It is known from simulations that the damper winding acts effectively under synchronous generator transient conditions. However, experimental proof has not been obtained yet. Thus, experiments on damper effects were conducted using a laboratory-scale power system. The damper winding of the tested generator consisted of five damper bars for each pole; the number of working damper bars could be changed manually. The damper currents at each bar were measured by a Rogowski coil. FFT analysis was applied to both the damper currents and armature currents under different operating conditions. The relationships between damper currents in the rotor and armature currents in the stator were made clearer than before. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(2): 33–42, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21278

Improvement of Three-phase Unbalance due to Connection of Dispersed Generator by Damper Windings of Synchronous Generator

SUMMARY It is well known in the numerical simulations of a synchronous generator that the damper winding contributes to suppressing three-phase circuit unbalance in power systems. However, an experimental study has not been performed yet. In this paper, we verify experimentally the suppression of three-phase unbalance by the damper windings. In order to simulate the three-phase unbalance, a 470-W dispersed generator of single-phase two-line type was connected to a three-phase laboratory-scale power system that included a 6-kVA synchronous generator. We measured and analyzed line voltages and currents as well as damper bar currents both with and without the dispersed generator. The influence of damper windings on the unbalance of the three-phase circuit was also investigated. The results show that the damper winding contributes to improving the three-phase unbalance. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(1): 43–50, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22305

Power System Characteristics of the SCFCL in Parallel With a Resistor in Series With a ZnO Device

Superconducting fault current limiters (SCFCLs) are expected to improve the reliability and stability of power systems. The 3-phase FCL system, which consists of 3 superconducting fault current limiters of transformer type in parallel with a resistor in series with a ZnO device, was proposed and its small model was designed and made. In a power system the FCL system is expected to limit the peak of the fault current inductively and also to consume the acceleration energy of the generators by means resistive component. The power system characteristics of the proposed FCL system was experimentally investigated by use of the model FCL and a laboratory scale power system simulator. The FCL system switches its impedance from inductive type (L-type) to inductive+resistive type (L + R-type) in a cycle due to the ZnO device. The peak of the fault current was limited in the L-type time interval and the energy was consumed in L + R-type interval. The proposed FCL system limited the fault current at the simulated fault and successfully recovered the stand-by mode in the model power system. At the same time, the energy consumption in the resistor reduced the accelerating energy of the generator and then improves the power system transient stability.

05/02087 Hardware implementation of a fuzzy logic stabilizer on a laboratory scale power system

05/02087 Hardware implementation of a fuzzy logic stabilizer on a laboratory scale power system

Hardware implementation of a fuzzy logic stabilizer on a laboratory scale power system

A power system stabilizer using the fuzzy logic is designed and implemented in this paper. Simulation studies are performed to evaluate the performance of the fuzzy logic power system stabilizer (FLPSS) and PID power system stabilizer (PIDPSS). Genetic algorithms have been used to optimize the parameters of the fuzzy and PID stabilizers. To validate the design, different types of disturbances are applied to the system and the results of both stabilizers are compared. The simulation studies show that the fuzzy stabilizer provides a relatively better performance comparable to that of the PIDPSS over a wide range of operating conditions. The FLPSS and PIDPSS have also been experimentally implemented using MATLAB/Real-Time Windows Target toolbox software on a laboratory set up to model a simple power system of 1 KVA machine connected to an infinite bus through a transmission line. Experimental tests and results revealed the effectiveness of FLPSS, especially in vulnerable operating points.

Analysis of a power oscillation damping scheme using a voltage-source inverter

In many cases, poorly damped electromechanical oscillations prevent utilities from increasing power transfer over existing transmission lines. One method of improving the damping of such oscillations is to actively vary the inductive reactance of a transmission line using a controllable series compensator. This paper describes an investigation into the use of a particular inverter-based compensator for power oscillation damping. Detailed simulation results and practical measurements of a small, but representative, laboratory-scale power system are presented to demonstrate that the inverter-based compensator can successfully be used to damp the electromechanical oscillations of a generator.