Changeable sensitivity and safety margin are proposed in this paper, which can avoid the voltage violation according to the operation of the current situation. A simulation test is presented to demonstrate the propose...
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This paper proposes an improved power sharing control scheme to achieve the accurate power sharing control and offer an improved PCC voltage regulation capability in islanding microgrid. An enhanced virtual impedance ...
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ISBN:
(纸本)9781479967698
This paper proposes an improved power sharing control scheme to achieve the accurate power sharing control and offer an improved PCC voltage regulation capability in islanding microgrid. An enhanced virtual impedance design is assumed in the conventional droop control scheme to manage distributed generation (DG) units to export the accurate reactive power in proportion to their rating. A point of common coupling (PCC) voltage restoration control is implemented to eliminate the PCC voltage deviation produced by the droop control effect and voltage drop effect on the impedance. This control scheme of each individual DG unit was designed to only use the locally measured feedback variables of inverter. It can realize accurate reactive power sharing and guarantee the PCC voltage quality. Matlab simulations are presented to show the effectiveness of proposed control performance in islanding microgrid.
This paper presents a new impedance-based fault distance calculation formulation for power distribution systems. The majority of low- or medium- voltage distribution systems are characterized by having numerous branch...
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ISBN:
(纸本)9781479975389
This paper presents a new impedance-based fault distance calculation formulation for power distribution systems. The majority of low- or medium- voltage distribution systems are characterized by having numerous branches, laterals and sub-laterals, highly unbalanced operation, and time varying load profile. All of these and other characteristics make most efficient approaches proposed for fault location in power distribution systems not applicable to distribution systems. The proposed method uses only measurements of voltage and current at the beginning of the analyzed feeder, and additional equipments such as, fault locators and monitoring devices are not needed to be installed in the distribution system. The apparent impedance is calculated by using the fundamental rms values of the measured voltage and current in this paper. This method is suitable to any kinds of fault and can be used to unbalanced power distribution systems, since it is derived in phase domain.
controllable load can actively participate in power balance control, which will have positive impact on power system operation. Lighting load takes a significant proportion in the electricity demand. Many features of ...
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ISBN:
(纸本)9781479950331
controllable load can actively participate in power balance control, which will have positive impact on power system operation. Lighting load takes a significant proportion in the electricity demand. Many features of Light emitting diodes (LEDs), small size, high luminous efficiency and long lifetime, make them very attractive for use in lighting. An Artificial Neural Network (ANN) control strategy is designed for LED luminance control in response to power system frequency. The pulse width modulation (PWM) dimming method is used to realize luminance control of LED. In order to regulate the LED power demand in response to frequency measurement signal, the ANN control strategy adjusts the ratio between the on-time and off-time of the PWM dimming signal of LED. Simulations are conducted to verify the effectiveness of the proposed the ANN control strategy.
Aiming at the disadvantage of Monte Carlo simulation method in slow convergence and using a great number of computation resources, this paper, based on analytical approach, builds a quick power system operational reli...
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Aiming at the disadvantage of Monte Carlo simulation method in slow convergence and using a great number of computation resources, this paper, based on analytical approach, builds a quick power system operational reliability analyzing model. From the viewpoint of operation, this model which is based on Markov chain, assumes that equipment failure rate follows exponential distribution. Its core content includes three aspects. Firstly, a convenient criterion, used to divide power system operation into three states, and the corresponding state-space transition expression are proposed for engineering application. Secondly, Markov state transition probability matrix is obtained based on power system operation historical data (or simulation data sample). Thirdly, based on state transition probability matrix and current operating state of power system, state transition probability, steady state probability and the mean time to first failure can be acquired very quickly. Example analysis using RBTS-BUS6 system, testified the Markov property of power system state transition and the efficiency of this study.
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