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This paper presents two different capacitors' voltage control schemes for modular multilevel converter (MMCs) with the application for back-to-back systems. Based on the derivation of the relationship between arm currents and active power of the MMCs in back-to-back system, the proposed scheme controls the currents of upper and lower arms independently in MMCs to achieve arm voltage balancing of capacitors...
The aim of optimal power flow is to discover an operating point that minimizes the generation cost while satisfying multiple operating constraints. Over the years, several techniques have been introduced to solve this non-linear optimization problem. In this paper, genetic algorithm deploying optimum non-uniform mutation rate and elitism has been used to solve this problem. After implementation of...
This paper presents a single-input dual-output (SIDO) converter with the simple structure which easily implements zero-voltage-switching (ZVS). In the power transmission mode, a case may appear that one output port of this SIDO converter is idling while another output port is working normally. In this paper, the bad effect of dead-time on achieving the idling output port is detailed analyzed, simulated...
Electrical power system is a large interrelated set-up, which requires a cautious design in order to supply continuous electricity to consumers without any divergence. Power electronics based Flexible Alternating Current Transmission Systems (FACTS) are devices, which are used to perk up the power system reliability and stability. Unified power flow controller (UPFC), which comes under the member...
An increasing adoption of rooftop photovoltaic (PV) generators presents a growing opportunity for the use of their grid-tie inverters to provide reactive power compensation on medium- and low-voltage distribution networks. This paper presents a generalized method based on particle swarm optimization (PSO) for determining how much reactive power is necessary to provide control over the voltage profile...
This paper proposes a hybrid three-phase load flow method for ungrounded distribution systems. Based on topology connectivity analysis, the system is partitioned into a mainline system and multiple tap systems. A Newton method with constant admittance matrix is used to solve the mainline system, such that zero impedance branches are merged into adjacent impedance branches to be considered, and constant...
The Modular Multilevel Converter (MMC) with full bridge cells is available for utility interactive inverter in high voltage line. When it is interconnected with power line, it is possible to control the active power flow so as to supply or charge the power in the power line. This research applied the MMC to grid connection system of distributed generator. Theory of the power flow control of the MMC...
The stochastic fluctuating offer of wind energy limits the capacity of supply in electrical grids by means of technical and economical reasons. To increase the supply, a concept of dynamic conditioning with the objective to increase the quality of supply was developed. The concept envisages support and management of the electrical grid respectively through compensation of active and reactive power...
The higher power density requirements in the future shipboard power systems are intended to be met by the adoption of Medium Voltage DC (MVDC) architecture. The MVDC shipboard power system is a typical case of the multi-terminal DC distribution system. Voltage Source Converters (VSC) with high voltage and power ratings and independent control over the real and reactive powers has many advantages over...
Distributed resources (DR) provide several challenges to distribution system analysis due to the models and solution techniques that are required for adequate representation and solution. Load flow analysis is used to determine voltage magnitude and phase angle at each system bus, power flow in each system branch, power injected by each generation source, and system losses. The power flow formulation...
Impacts of Distributed Generation (DG) resources on distribution networks have been studied. A Newton-Raphson algorithm based three phase unbalance power flow program has been developed to incorporate the effects of system unbalance and single phase DG injection. Power flow equations have been formulated and solved in phase coordinated form. Effects of substation load-tap changer, voltage regulator,...
The authors present a methodology for assessing centralized control of active and reactive distributed resources in a smart distribution grid. The methodology is based on three-phase optimal power flow and is able to deal properly with unbalanced conditions and both single-phase and three-phase control resources. Single-phase resources that can be exploited by means of this approach are domestic loads,...
In this paper, with respect to power flows of power systems with UPFC (Unified Power Flow Controller), a relatively detailed analysis and comparison to the models and algorithms reported in the open literature are made. A new power injection model and algorithm for power flow calculation of power systems with UPFC is proposed, and its principles and deriving processes are expatiated. The capacitance...
Due to the asynchronous generator has many negative factors such as large power fluctuation, poor transient performance, low energy efficiency, etc. The doubly fed induction generator(DFIG) is becoming a popular concept and thus the modeling of DFIG becomes an interesting research topic. This paper develops the DFIG model of power flow and third-order transient in which the power converter is simulated...
Radial distribution systems (RDS) have lines with high R/X ratios and hence Newton based methods were not reliable to solve their set of bus power balance equations. Historically, a recursive solution method using a set of voltage equations and its variants are very popular to determine a voltage solution of a RDS. Consequently, use of classical optimization was not possible. Recent developments in...
Unified Power Flow Controller (UPFC) has a promising effect on controlling the characteristics of the power system operation. During the contingency outage cases, the transmission lines are overloaded and the buses are subjected to voltage violations. Unified Power Flow Controller (UPFC) has both shunt and series controller effect inside its frame. This option gives the UPFC the power to control the...
In this paper, a sequential AC/DC power flow algorithm is proposed to solve networks containing Multi-terminal Voltage Source Converter High Voltage Direct Current (VSC MTDC) systems. In VSC HVDC technology, the converter losses add up to a significant fraction of the overall system losses. However, they are often neglected or not taken into account in a proper manner in VSC HVDC power flows. The...
Power system engineers are currently facing challenges to increase the power transfer capabilities of existing transmission system. This is where the power electronic Flexible AC Transmission Systems (FACTS) technology comes into effect. Simulation tools are available to check the influence of a FACTS device on the power system. In this paper we have tried to explain the different FACTS devices both...
Several papers have recognized the effect of uncertainties in system parameters on voltage stability analysis through probabilistic methods. In these papers, the unstable states are identified by the unsolvability of the power flow equations or the violation in the Voltage Stability Margin (VSM) minimum limit. However, voltage stability problems may also be associated with the loss of voltage controllability,...
??Smart Grid?? can be defined as getting the power to the customer the smartest way possible with the least amount of losses. One of the ways to control the power flow over the transmission line is to insert a phase angle regulating transformer (PAR) in the line. PAR's have long been dreaded by the protection engineer as a very complex device with many different currents that make it tedious at best...
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