Search results for "Distributed"

Power management of grid-connected photovoltaic inverter with storage battery

2011

With increased penetration of PV generation in the power grid, it becomes necessary to control the PV generation similar to the conventional power sources. Grid-connected PV systems equipped with storage batteries are capable of active power control. PV power generation can be either fed into the grid or stored in the battery. This paper presents a deterministic power management algorithm that uses closed-form approximations derived from analytical loss models. It can be configured to maximize the efficiency or the revenue in a liberalized electricity market. The battery controller emulates an optimum load-line in which the PV power is autonomously shared between the battery and the feed-in…

Hydrogen back-up power system with photovoltaic direct energy transfer regulation and interleaved boost for space applicattions

2012

This work details a power conditioning unit for photovoltaic/hydrogen based energy systems in space applications. The power conversion techniques applied are similar to the ones used on photovoltaic/battery space power systems. A direct energy transfer photovoltaic regulator is devised for feeding two outputs; the first output corresponds to the main unregulated battery bus and the second output sets a power path to feed an electrolyser. A modular fuel cell converter completes the system and operates when photovoltaic energy is not available or load demand exceeds the generated photovoltaic power, providing electrical power from a fuel cell. An ancillary battery, located in the main bus, di…

Performance evaluation of a multisource renewable power converter prototype

2014

Integration of distributed energy systems in micro-grid architecture for making a virtual power plant

2015

This paper presents a novel concept for increasing the penetration level of distributed renewable energy systems into the main electricity grid. When increasing the renewable energy penetration, it is important to implement the frequency based power delivery in distributed generators and work as traditional synchronous generators. This can be achieved by improving the power processing unit of each renewable generation units to work as active generators. But in existing grid architecture, the grid frequency is controlled as one common variable over the electricity grid. With such a method, it is difficult to use frequency based power sharing in small distributed generators and participate in…

Comparison of parallel implementation of some multi-level Schwarz methods for singularly perturbed parabolic problems

1999

Abstract Parallel multi-level algorithms combining a time discretization and an overlapping domain decomposition technique are applied to the numerical solution of singularly perturbed parabolic problems. Two methods based on the Schwarz alternating procedure are considered: a two-level method with auxiliary “correcting” subproblems as well as a three-level method with auxiliary “predicting” and “correcting” subproblems. Moreover, modifications of the methods using time extrapolation on subdomain interfaces are investigated. The emphasis is given to the description of the algorithms as well as their computer realization on a distributed memory multiprocessor computer. Numerical experiments …

Frequency dynamics of power systems with temporally distributed disturbances

2021

Abstract The frequency dynamics and stability of power systems is essentially affected by nature and characteristics of the disturbances occurring in the system. Conventionally, frequency transients are examined assuming a single disturbance applied at a given time. However, actual incidents in the power systems can be generally composed of a temporal sequence of events, and thus characterized by multiple power imbalances of different magnitudes and time offsets. The consideration of the effects of the temporal distribution of power imbalances is important for two main reasons: the impact on the frequency dynamics of the system in terms of frequency metrics such as minimum instantaneous fre…

Understanding 802.11e contention-based prioritization mechanisms and their coexistence with legacy 802.11 stations

2005

The IEEE 802.11e task group has reached a stable consensus on two basic contention-based priority mechanisms to promote for standardization: usage of different arbitration interframe spaces and usage of different minimum/maximum contention windows. The goal of this article is to provide a thorough understanding of the principles behind their operation. To this purpose, rather than limit our investigation to high-level (e.g. throughput and delay) performance figures, we take a closer look at their detailed operation, also in terms of low-level performance metrics (e.g., the probability of accessing specific channel slots). Our investigation on one hand confirms that AIFS differentiation prov…

A new capability index for dynamic process analysis

2013

Nowadays, the trend to produce with reduced specification limits width and at a low defectives rate seems to be irreversible. In such conditions, reliable evaluation of the process capability level represents a crucial activity to assess the quality related performance of a production process. By adopting the classical approach, such evaluation is performed by verifying the process in-control condition and by evaluating suitable capability indices. However, considering the natural dynamic behavior of production processes, i.e. the process variability over the time domain, the in-control condition characterizes only a part of the production process functioning cycle, the one with the lowest …

Negotiation mechanisms for capacity allocation in distributed enterprises

2003

Abstract The paper proposes an agent based approach for the capacity allocation in distributed enterprises, characterized by complex and articulated organizations and by geographically distributed production capacities contended by many product families. In such a scenario the process of allocating the production capacity to the single customer order is one the major bottlenecks of the production planning activity as far as many organizational decisional levels are involved and market turbulence implies a continuous retuning of the capacity allocation plan. A high grade of reactiveness is needed. Agent based approaches and negotiation models, by decentralizing the decisional control and sim…

The linear saturated decentralized strategy for constrained flow control is asymptotically optimal

2013

We present an algorithm for constrained network flow control in the presence of an unknown demand. Our algorithm is decentralized in the sense that it is implemented by a team of agents, each controlling just the flow on a single arc of the network based only on the buffer levels at the nodes at the extremes of the arc, while ignoring the actions of other agents and the network topology. We prove that our algorithm is also stabilizing and steady-state optimal. Specifically, we show that it asymptotically produces the minimum-norm flow. We finally generalize our algorithm to networks with a linear dynamics and we prove that certain least-square optimality properties still hold.