Shi-Jaw Chen

A highly efficient algorithm in treating current measurements for the branch-current-based distribution state estimation

A highly-linear branch-current-based state estimation model for a distribution system is proposed in this paper. This algorithm is based on the concepts presented by Baran and Kelley (see IEE Trans. on Power Systems, vol.10, no.1, p.483-91, 1995). Baran and Kelley proposed a novel branch-current-based approach to solve distribution state estimation. However, the treatment of current magnitude measurements and the complicated gain matrix by Baran and Kelley greatly degrades its value in real-world applications. The approach presented in this paper substantially revised the original method. A new algorithm with constant gain matrix and a decoupled form was developed. Tests have shown that the proposed method is robust, efficient and needs minimal storage requirement. The new algorithm provides a very good theoretical foundation for developing more applications and research in this area.

Bid-based dynamic economic dispatch with an efficient interior point algorithm

Abstract An efficient interior point algorithm for solving the bid-based dynamic economic dispatch (BBDED) problem is proposed in this paper. This algorithm is an extension of interior point quadratic programming (IPQP), and is called the predictor–corrector interior point quadratic programming (PCIPQP) algorithm. In a competitive electricity market, the dynamic economic dispatch has evolved to become bid-based framework to maximize the profits and achieve the resource scheduling. To generate a physically feasible dispatch and market spot prices, we form BBDED problem of dealing with various constraints such as ramp rates, transmission line capacity and emission constraints. In this paper, BBDED allows both supply-side and demand-side bids in the spot market, which includes multi-player, multi-period and a large number of constraints. Compared with the pure IPQP algorithm, PCIPQP is more attractive in performance, robustness, and the property of convergence. Many numerical tests reconfirmed the advantages of the predictor–corrector method.

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.

Non-Cooperative Game Model Applied to an Advanced Metering Infrastructure for Non-Technical Loss Screening in Micro-Distribution Systems

This paper proposes a non-cooperative game (NCG) model for non-technical loss (NTL) screening in micro-distribution systems. This model can compound an infra-structure with smart electric meters and fractional-order self-synchronization error formulation to distinguish illegal activities between profiled usages and non-technical usages. Then a NCG-based decision-making model is used to locate the abnormalities. Experimental results are presented to demonstrate the effectiveness of the proposed method.

An application of interior-point based OPF for system expansion with FACTS devices in a deregulated environment

This paper presents the formulation of AC optimal power flow (OPF) with deregulation issues and the effect of flexible AC transmission systems (FACTS) devices. A predictor-corrector interior-point nonlinear-programming (PCIPNLP) algorithm has been developed to solve the problem. Only minor changes are required to the present OPF function in a modern EMS for social welfare maximization to obtain the optimized bid-based dispatch and nodal spot prices. The incorporation of FACTS devices for system expansion can ease the difficulties caused by transmission congestion. It is found that PCIPNLP technique is very effective for the modified OPF solution for congestion relief under deregulation. Test results suggest that the incorporation of FACTS devices can not only utilize the existing lines, but also reduce load curtailment and increase market profit.

Photovoltaic Energy Conversion System Fault Detection Using Fractional-Order Color Relation Classifier in Microdistribution Systems

In this paper, we propose a photovoltaic (PV) energy conversion system (PVECS) fault detection scheme using a fractional-order color relation classifier in microdistribution systems. Based on electrical examination method, output power degradation is used to monitor physical conditions with changes in a PV array’s circuitry, including grounded faults, mismatch faults, bridged faults between two PV panels, and open-circuit faults. The PV array power depends on solar radiation and temperature, and maximum power point tracking (MPPT) control is used to maintain stable power supply to a microdistribution system in the event of a fault in the PVECS. The MPPT algorithm is employed to estimate the desired maximum power, which is then compared with the meter-read power. Fractional-order dynamic errors are determined to quantify output power degradation between the desired maximum power and the meter-read power. Then, a color relation analysis is used to separate normal conditions from fault events. For a PVECS with two panels in parallel, the simulation results demonstrate that the proposed method is suitable for real-time applications and is flexible for fault identification. Its detection rates exceeded 88.23% for six events.

Using Sprott Chaos Synchronization-Based Voltage Relays for Protection of Microdistribution Systems Against Faults

This paper proposes the use of Sprott chaos synchronization (SCS)-based voltage relays for fault protection in microdistribution systems (MDSs). The Sprott chaos system is used as a voltage detector to track the dynamic errors between the normal signal and disturbance signals. The proposed voltage relay is used to detect disturbances, such as serious voltage sag and swell, and uses a critical trigger time to isolate the fault section. It is proposed that the restoration strategy then restores the unfaulted but blackout zones, and confirms security operations, including load-power balance, power generation limits, voltage limits, and power-flow limits. Computer simulations are conducted by using an IEEE 30-bus power system and MDSs, to show the effectiveness of the proposed method.

The optimal loss reduction of distribution feeder based on special distribution transformers reconnection using genetic algorithm

Many utility companies of Taiwan Power Company (TPC) used the open wye-open delta (OYOD) transformers to serve various customers. This causes phase unbalance which is one of the prime reasons of ground relay tripping and extra line loss in the distribution system. Load reconnection, feeder reconfiguration and capacitor placement are common methods used to balance load or minimize power loss. The purpose of this paper is to reduce power loss by means of load reconnection of the prime phase sequence of the OYOD transformers used. Genetic algorithms (GAs) have been implemented for solving the optimal problem. Practical examples of TPC demonstrate that the proposed method is effective and available.

A new building algorithm for Z-Matrix

A new Z-Matrix building matrix for Z-Matrix is proposed in this paper. There have been a considerable number of papers in the literature that have presented methods in building Z-Matrix for large-scale power system, however, those methods only emphasize on the relationship between bus voltage and bus current injection. This paper provides a new aspect to observe the relation of bus voltage, bus current injection and branch current of the network. The building algorithm is achieved by a simple search technique with two developed matrices considering the tree and link branches of network, and is very suitable to be programmable. Using these two developed matrices, the relations of bus current injection vs. branch current and branch current vs. bus voltage can be distinct, and it is very helpful for observing the variations in short-circuit analysis or contingency analysis. a numerical example shows that the proposed method can be applied for large-scale power system more effectively and systematically than the conventional method.

Distribution feeder bus load estimations by measurement matching

The effectiveness of the entire distribution management system (DMS) relies on the data accuracy of load modeling/load estimation (LM/LE) in the distribution network. In this paper, feeder bus load estimations results obtained from a load scaling (LC) and backward/forward sweep (BFS) procedure are presented. The proposed technique makes use of the actual measurements (AM) data available from distribution automation (DA) and Advanced Metering Infrastructure (AMI) to adjust priori bus load data considered as pseudo measurements (PM). Two measurement matching procedures used to match the calculated data with the different types of measurement data at different feeder locations are described. Test results demonstrate that the proposed technique could lead to a load flow solution that matches AM and provides final load scaling values for PM.