Nanming Chen

Air conditioner direct load control by multi-pass dynamic programming

The dispatch of air conditioner direct load control (DLC) using multi-pass dynamic programming (MPDP) methods is presented. The objective of this work is to schedule the control of air conditioner load by MPDP methods such that the peak load reduction and production cost saving have optimum results for the whole study period. The algorithm can quickly converge to an optimal schedule. To demonstrate the effectiveness of this approach, results of a sample study on the Taiwan Power Company power system are described in this paper. >

Direct Search Method for Solving the Economic Dispatch Problem Considering Transmission Capacity Constraints

This paper develops an efficient and practical approach for solving the economic dispatch (ED) problem considering transmission capacity constraints. The direct search method (DSM) is chosen to handle a number of inequality and equality constraints and units with any kind of fuel cost functions. For improving the performance of the direct search procedure, a novel strategy with multilevel convergence is incorporated in the DSM to minimize the number of total iterations in the searching process. The validity, robustness, and effectiveness of the proposed approach is verified through numerical experiments for extended economic dispatch application.

Determination of optimal contract capacities and optimal sizes of battery energy storage systems for time-of-use rates industrial customers

This paper sets up a formulation to determine the optimal contract capacities and optimal sizes of battery energy storage systems for time-of-use rate customers. The advanced multi-pass dynamic programming and expert knowledge base rules are then applied to solve this problem. Two industrial customers of the Taiwan Power Company System are used as examples to test this algorithm. Results show that the optimal sizes of battery energy storage systems and the optimal contract capacities of customers during the life cycle of battery energy storage systems can be achieved by this algorithm; therefore the maximum economic benefits of battery energy storage systems for time-of-use rate customers can be estimated. >

Distribution factors of reactive power flow in transmission line and transformer outage studies

The authors present a fast and accurate method to calculate a set of distribution factors of reactive power flow for transmission line and transformer outage studies. The transmission branches are broken into two categories: transmission lines and transformers. Separate formulas are derived to calculate the distribution factors of the reactive power flow. A transmission line model is developed. The reactive power flow in a line is divided into two parts: the transmission part and the loss part. Based on this model, transmission line outages were simulated by power injections which cancel the reactive power flow in the outage lines. Formulas to calculate the distribution factors of the reactive power flow are derived using the decoupled load flow characteristic, network sensitivities, and the principle of superposition. The formulas to calculate the distribution factors of the reactive power flow in transformers are also derived. >

Area automatic generation control by multi-pass dynamic programming

Current research in Automatic Generation Control emphasizes coordination of the regulation and the economic dispatch functions into a single systems problem. A dynamic optimal control problem formulation has previously been suggested. In this paper optimal trajectories are found for up to five maneuverable generators, using a new multi-pass dynamic programming method to make such solutions feasible. Dynamic valve point loading and singular solutions are considered. Computer studies have applied the method to several examples, including sudden changes in area load, and supplying the morning rise in area load.

Optimal capacity of the battery energy storage system in a power system

This paper investigates the optimal capacity of a battery energy storage system in a power system. The Taiwan Power Company System is used as an example system to test this algorithm. Results show that the maximum economic benefit of battery energy storage in a power system can be achieved by this algorithm. >

Electric network solutions of DC transit systems with inverting substations

A detailed model of the R-L-fed inverting substation, for use of power flow and harmonic studies in DC electrified transit systems, has been presented in this paper. A unified Newton-Raphson method is adopted as the solution approach of the AC/DC power flows. The harmonic study is performed by the Y-bus method using the derived harmonic current injections of the converter. The Chungho Line of Taipei Rapid Transit Systems is given as a numerical example system. Effects of the application of inverting substations to the example system are investigated. The detailed converter model and the fast power flow algorithm can be easily applied to train simulators to complete a more accurate and rapid electric network solution of transit systems.

Particle-Swarm-Optimization-Based Nonintrusive Demand Monitoring and Load Identification in Smart Meters

Compared with the traditional load monitoring system, a nonintrusive load monitoring (NILM) system is simple to install and does not need an individual sensor for each load. Accordingly, the NILM system can be applied for wide load monitoring and become a powerful energy management and measurement system. Although several NILM algorithms have been developed during the last two decades, recognition accuracy and computational efficiency remain as challenges. To minimize training time and improve recognition accuracy, particle swarm optimization is adopted in this paper to optimize parameters of training algorithms in artificial neural networks. The proposed algorithm is verified through the combination of Electromagnetic Transients Program simulations and field measurements. The results indicate that the proposed method significantly improves recognition accuracy and computational efficiency under multiple operation conditions.

A New Method for Power Current Measurement Using a Coreless Hall Effect Current Transformer

A new method for performing power current measurement is proposed; this method involves the use of Hall sensors without iron cores. A new apparatus for implementing this method, called coreless Hall-effect current transformer (HCT), has been developed. The HCT consists of four Hall sensors connected to a weighted adder. Four Hall sensors are symmetrically attached to an electric conducting cable, and the output of the sensors is connected to the weighted adder. The weighted adder performs the “average” operation, thereby obtaining the average voltage. Since the average Hall voltage is obtained, the HCT can eliminate the ambient interference. A measurement framework is designed and implemented to compare a series of waveforms obtained by HCTs with those measured by traditional current transformers (CTs) and linear CTs. Current measurement results show that an HCT can measure current with greater accuracy than traditional CTs. Moreover, in the presence of faults, HCTs do not encounter problems related to saturation that exist in traditional CTs.

A detailed R-L fed bridge converter model for power flow studies in industrial AC/DC power systems

Because of lower voltage levels and smaller power ratings, the R/X ratio of commutation impedance in industrial AC/DC distribution systems is usually higher than that in HVDC transmission systems. Considerable discrepancies may therefore occur in industrial AC/DC power flow results, especially the reactive power consumption of converters, if the commutation resistances of the converters are neglected. To describe the effects of commutation impedance on converter operations and to precisely relate the fundamental line current and DC output current of the converter, a detailed model of the bridge converter with commutation impedance for use of Newton-Raphson power flow studies in industrial AC/DC power systems is derived in this paper. A coal mine power system and a DC electrified transit railway system with regenerative braking function, a part of Taipei Rapid Transit Systems under planning, have been analyzed to show the improved accuracy and good convergence characteristics of the developed Newton-Raphson power flow formulation with the proposed converter model. >