• KIEE International Transactions on Power Engineering
• /
• v.4A no.4
• /
• pp.262-267
• /
• 2004

With the advent of electric power systems moving from a vertically integrated structure to a deregulated environment, calculating reactive power service charges has become a new and challenging theme for market operators. This paper examines various methods for reactive power management adopted throughout various deregulated foreign and domestic markets and then proposes an innovative method to calculate reactive power service charges using a reactive power market in a wholesale electricity market. The reactive power market is operated based on bids from the generating sources and it settles on uniform prices by running the reactive OPF programs of the day-ahead electricity market. The proposed method takes into account recovering not only the costs of installed capacity but also the lost opportunity costs incurred by reducing active power output to increase reactive power production. Based on the result of the reactive OPF program, the generators that produce reactive power within the obligatory range do not make payments whereas the generators producing reactive power beyond the obligatory range receive compensation by the price determined in the market. A numerical sample study is carried out to illustrate the processes and appropriateness of the proposed method.

• Journal of the Korean Ceramic Society
• /
• v.49 no.4
• /
• pp.308-317
• /
• 2012

Reactive processing, such as reactive hot pressing (RHP) and reactive spark plasma sintering (R-SPS), is effective densification method to prepare $ZrB_2$-based ultra high temperature ceramics (UHTCs). The present paper reviewed some typical reactive processing of $ZrB_2$-based UHTCs. All the reactions from the starting materials in the reactive processing are thermodynamically favorable, which generate enough energy and driving force for the densification of the final products under a relatively low temperature. Besides, compared with non-reactive processing, anisotropic $ZrB_2$ grains, such as $ZrB_2$ platelets, can only be obtained in the reactive processing, resulting in an improvement of the mechanical properties.

• Textile Coloration and Finishing
• /
• v.25 no.4
• /
• pp.262-270
• /
• 2013

Temporarily solubilized reactive disperse dyes containing ${\beta}$-sulfatoethylsulfonyl group were applied to 100% meta-aramid knitted fabric and their dyeing properties were investigated. Reactive disperse dyes showed relatively high K/S values on meta-aramid fabric when compared with conventional disperse dye or reactive dye, which showed very low K/S values. Color yields of reactive disperse dyes were highly dependent on dyeing pH and optimum results were obtained at pH 6. Percent exhaustion of reactive disperse dye on meta-aramid fabric was over 80% at 2% o.w.f of dye concentration. Wash fastness of pyridone-based reactive disperse dyes was very good to excellent while that of aminoazobenzene reactive disperse dyes was medium to good. Light fastness of all the reactive disperse dyes was very poor which seems to be due to the low photostability of meta-aramid fiber itself.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.1
• /
• pp.8-20
• /
• 2013

This paper deals with the concept design of HVDC system for controlling AC network reactive power. HVDC system can control active power and reactive power and the control concept of reactive power is similar to SVC(Static Var Compensator). Reactive power is controlled by adjusting firing angle of HVDC system under the condition that AC filters are switched. Reactive power depends on AC voltage condition, considering the steady-state and transient state to maintain the stable operation of AC network in the viewpoint of voltage stability. Therefore, in the design stage of HVDC, the reactive power required in the AC network must be considered. For the calculation of operation angle in HVDC system, the expected reactive power demand and supply status is examined at each AC system bus. The required reactive power affects the determination of the operation angle of HVDC. That is, the range of "control deadband" of operation angle should have the capability supplying the required reactive power. Finally, the reactive power control concepts is applied to 1GW BTB Pyeongtaek-Dangjin HVDC system.

• KIEE International Transactions on Power Engineering
• /
• v.11A no.4
• /
• pp.39-44
• /
• 2001

As electric power systems have been moving from vertically integrated utilities to a deregulated environment, the charging of reactive power management is a new challenging them for market operators. This paper proposes a new methodology to compute the costs of providing reactive power management service in a competitive electrical power market. The proposed formulation, which is basically different from those shown in the literature, consists of two parts. One is to recover investment capital costs of reactive power supporting equipment based on a reactive power flow tracing algorithm. The other is to recover operational costs based on variable spot prices using the optimal power flow algorithm. The charging shapes resulted from the proposed approach exhibit a quite good meaning viewed from a practical sense. It turns out that reactive power charged are mostly due to recovery of capital costs and slightly due to recovery of operational costs. The methods can be useful in providing additional insight into power system operation and can be used to determined tariffs of a reactive power management service.

• Journal of Electrical Engineering and Technology
• /
• v.4 no.3
• /
• pp.337-345
• /
• 2009

Deregulation in power industry has made the reactive power ancillary service management a critical task to power system operators from both technical and economic perspectives. Reactive power management in power systems is a complex combinatorial optimization problem involving nonlinear functions with multiple local minima and nonlinear constraints. This paper proposes a practical market-based reactive power ancillary service management scheme to tackle the challenge. In this paper a new model for voltage security and reactive power management is presented. The proposed model minimizes reactive support cost as an economic aspect and insures the voltage security as a technical constraint. For modeling validation study, two optimization algorithm, a genetic algorithm (GA) and particle swarm optimization (PSO) method are used to solve the problem of optimum allocation of reactive power in power systems under open market environment and the results are compared. As a case study, the IEEE-30 bus power system is used. Results show that the algorithm is well competent for optimal allocation of reactive power under practical constraints and price based conditions.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2004.03b
• /
• pp.869-872
• /
• 2004

A study on the solidification of sludge by reactive amendment agent was carried out in this paper. The reactive amendment agent used in this study is mainly composed of inorganic solidification agent and reactive adsorptive material. The reactive agent has a function of soil-cement-agent solidification and harmlessness of contaminant in waste. The reactive agent is environmentally friendly material to the surrounding environment. In this study, a series of tests and experiments including unconfined compressive strength, permeability, pH test, constituent analysis, leaching test were carried out to analyse engineering and environmental characteristics of solidified sludge treated reactive agent. The result of this research shows that the solidified sludge treated reactive agent is increased in strength and decreased in contaminant concentration.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.53 no.3
• /
• pp.182-186
• /
• 2004

In this paper, the cost for capacitive reactive flower is evaluated considering the deregulation environment. For the cost assessment of reactive power, the duration curve of reactive power demand is introduced and investigated. Also, a guideline is suggested to estimate the Q-cost by using the inverse of the Q-demand duration curve. In order to obtain optimal real reactive power allocation, a new algorithm is proposed by using the piecewise linearization of the inverse of the Q-demand duration curve and the Linear Programming technique. The proposed method is tested with sample systems using MATLAB. The test results show that the algorithm yields reasonable reactive power allocation and Provides fair cost evaluation for reactive power.

• Textile Coloration and Finishing
• /
• v.16 no.1
• /
• pp.26-33
• /
• 2004

Two reactive disperse dyes having $\alpha$-bromoacrylamide or acrylamide group were synthesized and their dyeing properties were compared with a disperse dye. Dyeing properties of reactive disperse dyes were strongly influenced by the chemical structure of reactive group. The amount of absorbed reactive disperse dye containing $\alpha$-bromoacrylamide group on polyester fiber was less than the disperse dye, and that on nylon fiber was much higher. When polyester and nylon fiber were simultaneously dyed in a dye pot, nylon fiber absorbed the reactive disperse dye more than polyester fiber. The reactive disperse dye having acrylamide group could reduces difference in color depth to a large extent, but the application of carrier or variation of dyebath pH were not sufficient for giving the same color depth to both fibers. The N/P union fabric could be dyed with the reactive disperse dye and its wash fastness were good to excellent.

• Proceedings of the KIPE Conference
• /
• 2014.07a
• /
• pp.213-214
• /
• 2014

This paper compares two instantaneous reactive power definitions in DFIG wind turbine with a back-to-back three-level neutral-point clamped voltage source converter under unbalanced grid conditions. In general, conventional definition of instantaneous reactive power is obtained by taking an imaginary component of complex power. The other definition of instantaneous reactive power can be developed based on a set of voltages lagging the grid input voltages by 90 degree. A complex quantity referred as a quadrature complex power is defined. Proposed definition of instantaneous reactive power is derived by taking a real component of quadrature complex power. The characteristics of two instantaneous reactive power definitions are compared using the ripple-free stator active power control algorithm in DFIG. Instantaneous reactive power definition based on quadrature complex power has a simpler current reference calculation control block. Ripple of instantaneous active and reactive power has the same magnitude unlike in conventional definition under grid unbalance. Comparison results of two instantaneous reactive power definitions are verified through simulation.