Active Power Values Research Articles

A new HBMO algorithm for multiobjective daily Volt/Var control in distribution systems considering Distributed Generators

In recent years, Distributed Generators (DGs) connected to the distribution network have received increasing attention. The connection of enormous DGs into existing distribution network changes the operation of distribution systems. Because of the small X/ R ratio and radial structure of distribution systems, DGs affect the daily Volt/Var control. This paper presents a new algorithm for multiobjective daily Volt/Var control in distribution systems including Distributed Generators (DGs). The objectives are costs of energy generation by DGs and distribution companies, electrical energy losses and the voltage deviations for the next day. A new optimization algorithm based on a Chaotic Improved Honey Bee Mating Optimization (CIHBMO) is proposed to determine the active power values of DGs, reactive power values of capacitors and tap positions of transformers for the next day. Since objectives are not the same, a fuzzy system is used to calculate the best solution. The plausibility of the proposed algorithm is demonstrated and its performance is compared with other methods on a 69-bus distribution feeder. Simulation results illustrate that the proposed algorithm has better outperforms the other algorithms.

Method of Reducing Error in Calculations of Active Power from Signal Samples

The paper presents the results of investigations into several methods of calculating the active power value from current and voltage signal samples. The accuracy attainable for nonsinusoidal signals whose frequency differs from the nominal one was determined. A new active power calculation method ensuring accurate results for sampling over two signal periods is proposed. The method uses a very simple computing algorithm.

Control scheme studies of voltage source type superconducting magnetic energy storage (SMES) under asymmetrical voltage

Symmetry of system voltage is very important to the performance of superconducting magnetic energy storage (SMES). Both theoretical analysis and simulation results show that, negative sequence current and 2nd harmonic power will be injected into the system, when conventional symmetrical fire is used in power conditioning system (PCS) of SMES. Two indices are used to evaluate the performance of PCS of SMES: the relative error of average value and 2nd harmonic component of active power supplied by SMES. To improve the performance of SMES, symmetrical vector control is put forward in this paper. According to the objective, there are three kinds of symmetrical vector control: positive sequence voltage control, zero negative sequence current control and constant active power control. Their principles are presented and improvements on the performance of SMES are verified by electromagnetic transient simulation. It shows that all those three methods decrease the relative error of average value of active power supplied by SMES. Zero negative sequence current control and constant active power control can also limit the relative error of 2nd harmonic component of active power supplied by SMES effectively.