Tung-Sheng Zhan

A Hybrid Current-Power Optimal Power Flow Technique

An equivalent current injection (ECI)-based hybrid current-power optimal power flow (OPF) model is proposed in this paper, and the predictor-corrector interior point algorithm (PCIPA) is tailored to fit the OPF for solving nonlinear programming (NLP) problems. The proposed method can further decompose into two subproblems. The computational results of IEEE 9 to 300 buses have shown that the proposed algorithms can enhance the performance in terms of the number of iterations, memory storages, and CPU times.

Multiple-frequency three-phase load flow for harmonic analysis

A multiple-frequency three-phase load-flow model was developed in this paper. There are two new submodels including the fundamental power flow (FPF) and harmonic frequency power-flow (HPF) model. In FPF, models of electrical elements and PV buses were treated in the form of current injections in a transmission system. The standard Fourier analysis was used to deal with the harmonic loads to get injection currents. With harmonic currents as equivalent current sources, the HPF can be derived. Besides, the decoupled fast version of FPF and HPF, called DFPF and DHPF, were also proposed in this paper. Test results show that the proposed general-purpose methods are better performers than conventional power-flow solutions and are very robust.

Nontechnical Loss and Outage Detection Using Fractional-Order Self-Synchronization Error-Based Fuzzy Petri Nets in Micro-Distribution Systems

Load management is a challenging issue in micro-distribution systems dealing with power utilities. To efficiently detect fraudulent and abnormal consumption, this paper proposes the use of fractional-order self-synchronization error-based Fuzzy Petri nets (FPNs) to detect nontechnical losses and outage events. Under the advanced metering infrastructure technique, the Sprott system is a feature extractor, which tracks the differences between profiled usages and irregular usages, such as illegal and fault events. Thus, fraudulent consumption, outages, and service restoration activities can be pointed out, randomly initiated, and terminated in a real-time application. Multiple FPNs-based making-decision systems are used to locate abnormalities. Computer simulations are conducted using an IEEE 30-bus power system and medium-scale micro-distribution systems to show the effectiveness of the proposed method.

Modified PSO Method for Robust Control of 3RPS Parallel Manipulators

We propose an effective method to design a modified particle swarm optimization (MPSO) singularity control method for a fully parallel robot manipulator. By adopting MPSO to obtain simple and effective estimated damping values, the result automatically adjusts the damping value around a singular point and greatly improves the accuracy of system responses. This method works by damping accelerations of the end effector, so that accelerations along the degenerated directions are zero at a singular point. These velocities, however, may not be zero in some situations, in which case, fluctuations will be encountered around a singular point. To overcome this drawback, we propose a control scheme that uses both damped acceleration and damped velocity, called the hybrid damped resolved-acceleration control (HDRAC) scheme. The MPSO optimization method can immediately provide optimal damping factors when used in an online application. Our proposed approach offers such superior features as easy implementation, stable convergence characteristics, and good computational efficiency. The main advantage of the HDRAC with MPSO in the 3RPS parallel manipulator control system is that it is not necessary for the system to plan its path for avoiding the singular point; thus, the workspace can be improved. Illustrative examples are provided to show the effectiveness of this HDRAC in practical applications, and experimental results verifying the utility of the proposed control scheme are presented.

Distribution system reliability worth analysis with the customer cost model based on RBF neural network

Reliability worth analysis is an important tool for distribution systems planning and operations. The interruption cost model used in the analysis directly affects the accuracy of the reliability worth evaluation. In this paper, two interruption cost models including an average or aggregated model (AAM), and a probabilistic distribution model (PDM) are proposed by using the radial basis function (RBF) neural network with orthogonal least-squares (OLS) learning method. The residential and industrial interruption costs in AAM and PDM were integrated by the proposed neural network technique. A Monte-Carlo time sequential simulation technique was adopted for worth assessment. The technique is tested by evaluating the reliability worth of a Taipower system for the installation of disconnected switches, lateral fuses, transformers, and alternative supplies. The results show that the two cost models result in very different interruption costs, and PDM may be more realistic in modeling the system.

Design and Implementation of the Dual-Axis Solar Tracking System

The capability of photovoltaic (PV) panel to generate energy approximately follows the intensity of the sunlight on the panel. A dual-axis solar programmable logical controller (PLC) based automatic tracking system and its supervisory and control system was designed and implemented in this paper. The proposed automatic tracking system controls elevation and orientation angles of solar panels such that the panels always maintain perpendicular to the sunlight. The measured variables of our automatic solar tracking system were compared with those of a fixed-angle PV system. The results indicated that the automatic solar tracking system is low-cost, reliable and efficient. As a result of the experiment, the electricity generated by the proposed tracking system has an overall increase of about 8%~25% more than the fix-angle PV system.

Singularity robustness of the 3RPS parallel manipulator by using the damped-rate resolved-acceleration control

A novel singularity control method for a fully parallel robot manipulator was proposed in this paper. The damped least-square method has frequently been used to solve the singularity problem of resolved-acceleration control schemes. It works by damping accelerations of the end-effector, so that accelerations in the degenerated directions are zero at a singular point. However, its velocities may not be zero in some situations, in those cases they will encounter fluctuations around the singular point. In this paper, the control using damped velocity, being called the damped-rate resolved-acceleration control scheme (DRRAC) is proposed to overcome this drawback. We will show that the DRRAC is asymptotically stable, and discuss its convergent properties. The main advantage of the DRRAC in the 3RPS parallel manipulator control system is not to plan its path to avoid the singular point, and could improve the workspace. Illustrative examples are given to show its effectiveness in practical applications, and experimental results are taken to verify the proposed control scheme.

Identification of Flat Panel Glass-Handling Mechanism

The dynamic equations of a flat panel glass-handling robot driven by a permanent magnet synchronous motor (PMSM) are derived by use of Hamilton’s principle for the rigid and flexible models. In this paper, we adopt a new modified particle swarm optimization (MPSO) to identify all the parameters of the robot and PMSM simultaneously. This new algorithm is added with a “distance” term in the traditional PSO’s fitness function to avoid converging to a local optimum. It is found that the MPSO method can obtain optimal high-quality solutions with high calculation efficiency. In this study, the convergence characteristics of the real-coded genetic algorithm (RGA), PSO and MPSO are compared to demonstrate that the MPSO is superior to the others on identification of the dynamic flexible model.

Turbine-generator blade and shaft torisonal torques due to line faults in six-phase transmission systems evolved from three-phase double-circuit line systems

Due to a restricted right-of-way and many factors, some of the local areas in Taiwan have become increasingly difficult to build new transmission lines. Since the majority of Taiwan power loads are located in the Norton, the demand of promoting transmission power could be of great urgency owing to the large amounts of power transferring from the South to the Norton. Aimed at overcoming this problem without changing the original conductors of the double-circuit transmission lines, the six-phase transmission scheme which could be one of the best schemes is presented and has several advantages such as transient stability enhancement, minimal corona, electric and magnetic fields, and radio interferences. As a result of the successful commercial operation of six-phase transmissions, the utility planner inevitably faces with the issue for the impact of turbine-generator torsional vibrations in the initial stage of the expansion into the a six-phase network. From the simulation comparisons between the three-phase double-circuit and evolved six-phase system, the latter offers better stability characteristic without deteriorating torsional vibrations from the viewpoint of the same line voltages. For the case of the same transmission capability, it significantly reduces the torsional vibrations. These conclusions provide a constructive suggestion for the department of generation and transmission.

Predictor-Corrector Interior Point Algorithm for Current-Based Optimal Power Flow

This paper presents a current-based optimal power flow (OPF) with predictor-corrector interior point algorithm (PCIPA). The distinctive features of this OPF formulation are: i) the elements of Hessian matrix are all real, ii) the objective function and constraints are quadratic functions and such quadratic properties are explored in the development of a robust nonlinear OPF solution procedure. This paper also presents the proposed method can further decomposes into two optimal sub-problems (active and reactive). The computational results on power systems of IEEE 9 to 118 buses have shown that the proposed algorithms are very effective.