Power-flow study

About: Power-flow study is a research topic. Over the lifetime, 8091 publications have been published within this topic receiving 155053 citations. The topic is also known as: load-flow study.

Optimal placement of distributed generation with sensitivity factors considering voltage stability and losses indices

Abstract: Loss minimization in distribution networks has considered as great significance recently since the trend to the distribution generation will require the most efficient operating scenario for economic viability variations. Furthermore, voltage instability phenomena can occur in distribution systems and caused a major blackout in the network. The decline of voltage stability level will restrict the increase of load served by distribution companies. To control distribution networks, it can be used from Distributed Generation (DG). DG is increasingly drawing great attention and development of DGs will bring new chances to traditional distribution systems. However, Installation of DG in non-optimal places can result in an increasing in system losses, voltage problems, etc. This paper presents two scenarios for distributed generation placement in a distributions system. In the first scenario only minimizing the total real power losses in the system is considered. Both the optimal size and location are obtained as outputs from the exact loss formula. The next scenario considered the voltage stability index (SI) to find optimum placement. In these scenarios Different DG placements are compared in terms of power loss, loadability and voltage stability index. To improve power transfer capacity, two line stability indices have been introduced. Distribution power flow solution algorithm is based on the equivalent current injection that uses the bus-injection to branch-current (BIBC) and branch-current to bus-voltage (BCBV) matrices. These scenarios are executed on typical 33 and 30 bus test system and yields efficiency in improvement of voltage profile and reduction of power losses; it also may permit an increase in power transfer capacity, maximum loading, and voltage stability margin.

Parallel connection of different types of AC power supplies of differing capacities

Abstract: A power inverting method and system for connecting a plurality of AC power supplies to a common bus line in parallel wherein the AC power supplies are independently controlled so that power supplies with different rating characteristics can be coupled to the common bus line without adverse effects such as the existence of cross currents flowing between the different power supplies. In each AC power supply there is provided a system parameter calculating unit for calculating optimum load current, system impedance and output voltage parameters of the power supply which are then output to a reference data producing unit which generates appropriate feedback voltage and phase signals for output to a voltage controller and a phase synchronization controller, respectively. The voltage controller and phase synchronization controller output feedback signals to a power inverter which varies the power supply output. Using such feedback control in each of the plurality of power supply units enables a constant current to be output to a load on the system and eliminates the possibility of cross currents between the various power supply units.

Optimal power flow incorporating voltage collapse constraints

Abstract: The paper presents applications of optimization techniques to voltage collapse studies. First a "maximum distance to voltage collapse" algorithm that incorporates constraints on the current operating conditions is presented. Second, an optimal power flow formulation that incorporates voltage-stability criteria is proposed. The algorithms are tested on a 30-bus system using a standard power flow model, where the effect of limits on the maximum loading point is demonstrated.

Management of an electric power generation and storage system

Abstract: In one technique of the present invention, DC electric power from a DC bus is inverted to provide AC electricity to one or more electrical loads, and AC power from a power generating device is rectified to provide a first variable amount of electric power to the DC bus. This technique also includes determining power applied to the electrical loads, and dynamically controlling the amount of power supplied from the power generating device and an electrical energy storage device in response to the power applied to the loads.

A Series-Stacked Power Delivery Architecture With Isolated Differential Power Conversion for Data Centers

Abstract: In this paper, an alternative method to achieve more efficient dc power distribution and voltage regulation for future data centers is presented. This paper describes a series-stacked power delivery architecture, where servers are connected electrically in series, thereby, providing inherent step down of voltage. Server voltage regulation is performed by differential power converters, which only process the mismatch power between servers. The bulk power flows with no power processing, yielding greatly increased system efficiency compared to conventional architectures. We demonstrate the series-connected architecture with an experimental proof of concept and compare the proposed architecture with a conventional dc power delivery architecture employing a best-in-class power supply unit for servers. The proposed power delivery architecture is validated with a series-stacked server rack consisting of four 12 V servers, powered from a 48 V dc bus, performing two different real-world operations: web traffic management and computation. Through experimental measurements, we demonstrate up to a 40x reduction in power conversion losses compared to state-of-the-art hardware, and an overall best-case system conversion efficiency of 99.89%.