Power optimizer

About: Power optimizer is a research topic. Over the lifetime, 10525 publications have been published within this topic receiving 199245 citations.

Power slope targeting for DC generators

Abstract: A simple feedback control loop, in conjunction with an improved maximum power point tracking intermediate controller, can be used ensure efficient operation of a power generator. The improved maximum power point tracking controller operates the generator at its maximum allowable power point. A power output of the generator is measured and compared to a power output setpoint. Operating characteristics of the generator are then adjusted to cause the maximum allowable power point and measured power output to approximate the power output setpoint. Although applicable to all types of generators, this is particularly beneficial in fuel cell generator systems and other systems where damage to generator components can occur if operated above a maximum allowable power output level. In other systems, the maximum allowable power output may approach or equal a maximum power point (or maximum possible power point).

An Autonomous Energy Harvesting Power Management Unit With Digital Regulation for IoT Applications

Abstract: Efforts towards energy-harvesting solutions are targeted for wireless sensor node applications and focus on performing maximum power extraction and storing power, yet efforts to deliver a regulated supply to voltage-sensitive blocks in power-limited applications has yet to be fully achieved. This paper presents a low-power, autonomous power management unit (PMU) able to perform maximum power point tracking for dc-type renewable sources. It includes a startup circuit fed directly from the renewable source. The PMU delivers a regulated output voltage through a digital LDO. The main step-up operation is performed through a dynamically controlled, power-aware, capacitive dc–dc converter that performs the required voltage gain procedure. Then, the digital LDO receives the EH source power density information from the dc–dc converter and provides regulation. Information about the source-power density availability is passed on to the digital LDO in order to select the best pass device size from a bank of three arrays. The PMU allows power consumption decrease by reducing the gate driving losses associated with large pass transistor devices, and it enhances efficiency. The system was fabricated in 180 nm CMOS process, and maximum end-to-end efficiency was measured at 57% with 1.75 mW of input power.

Uncertainty analysis for wind energy production with dynamic power curves

Abstract: The production of wind energy often involves uncertainties due to the stochastic nature of wind speeds and the variation of the power curve. The latter occurs when a fleet of wind turbine generators (WTG) of the same type are deployed in the wind farm, yet each generator may produce different amounts of powers given the same wind speed. This paper aims to characterize the dynamics of the wind energy production and estimate the power uncertainty when a WTG operates between the cut-in wind speed and the rated wind speed. We propose a probabilistic model to characterize the dynamics of the output power assuming the power follows the normal distribution with a varying mean and a constant standard deviation. Based on that condition, the mean and the variance for the total wind energy production are derived by incorporating the stochastic wind speed and the power dynamics. Both simulations and numerical examples are provided to verify and illustrate the new model, respectively.

DC Distributed Power Systems - Analysis, Design and Control for a Renewable Energy System

Abstract: Renewable energy systems are likely to become wide spread in the future due to environmental demands. As a consequence of the dispersed nature of renewable energy systems, this implies that there will be a distributed generation of electric power. Since most of the distributed electrical energy sources do not provide their electric power at line frequency and voltage, a DC bus is a useful common connection for several such sources. Due to the differences in output voltage among the sources, depending on both the type of source and their actual operating point, the sources are connected to the DC power system via power electronic converters. The intention behind the presented work is not to replace the existing AC power system, but to include local DC power systems. The AC and DC power systems are connected at some points in the network. The renewable energy sources are weak compared to the present hydro power and nuclear power plants, resulting in a need of power conditioning before the renewable energy is fed to the transmission lines. The benefit of such an approach is that power conditioning is applied on a central level, i.e. at the interface between the AC and DC power systems. Present DC transmission systems are discussed and investigated in simulations. Then, different methods for load sharing and voltage control are discussed. Especially, the voltage droop control scheme is examined thoroughly. Since the droop control method does not require any high-speed communication between sources and loads, this is considered the most suitable for DC distributed power systems. The voltage feed back design of the controller also results in a specification of the DC bus capacitors (equivalents to DC link capacitors of single converters) needed for filtering. If the converters in the DC distribution system are equipped with capacitors selected from this design criterion and if the DC bus impedance is neglected, the source converters share the total load equally in per unit. The same DC distribution bus configuration is studied in a wind power application. Especially the dynamic properties of load-source interactions are highlighted. They are interesting since the sources are considered weak for a distributed power system. This is illustrated with simulations where the power is fed from wind turbines only and constant power loads are controlled at the same time as the DC bus voltage level. Personal safety and prevention of property damage are important factors of conventional AC power systems. A grounding scheme for the DC distribution system together with algorithms for detection of ground faults, are presented. The proposed method detects ground faults on both the AC and DC sides and is extended to cover short circuit faults with a minor work effort. Experimental verifications follow the theoretical investigations introduced above. First, dynamic properties are studied and the behavior predicted from theoretical analysis and simulations is verified. Then, load sharing is investigated. Also in this investigation, the experimental results agree with the simulated. (Less)