Power optimizer

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

Dynamic operation and control of a hybrid wind-diesel stand alone power systems

Abstract: This paper presents the dynamic operation and control strategies of a hybrid wind-diesel-battery energy storage based power supply system for isolated communities are investigated. Control strategies for voltage and frequency stabilization and efficient power flow among the hybrid system components are developed. The voltage and frequency of the hybrid wind-diesel system is controlled either by a load side inverter or by diesel generation depending on the wind conditions. During high penetration of wind, the wind turbine supplies the required power to the load. A battery energy storage system is connected to the dc-link to balance the power generated from the wind turbine and the power demand by load. Under low wind conditions, a diesel generator is used with wind energy conversion system to generate the required power to the load. A power sharing technique is developed to allocate power generation for diesel generator in low wind conditions. Results show that the control strategies work very well under dynamic and steady state condition to supply power to the load.

Apparatus and method of detecting ground fault in power conversion system

Abstract: In a power conversion system having a DC power supply which has an almost fixed DC voltage to ground and a predetermined stray capacitance to ground and outputs a DC power, and a power converter which converts the DC power output from the DC power supply into an AC power by switching, the phase of an AC voltage to ground generated in the DC power supply by switching is detected, the phase of an AC ground fault current that flows through the stray capacitance to ground and the ground fault resistance of the DC power supply is detected, and the difference between the two detected phases is compared with a predetermined threshold value, thereby determining a DC ground fault in the DC power supply. With this arrangement, the ground fault state of the DC power supply can more accurately be detected. In addition, the operation efficiency of the power conversion system can be increased.

Analysis of Inverter-Voltage Influence on Distributed MPPT Architecture Performance

Abstract: More and more distributed maximum power point tracking (DMPPT) architectures, based on a dc-dc converter for every single photovoltaic (PV) panel, are being released and launched to the market as an alternative to traditional MPPT configurations. Ideally, they can solve any mismatching problem, but actually, this is not always feasible. This paper analyzes the static performance of this kind of architectures in order to determine the key factors to bear in mind in the design of the system. Above all, this paper points out the inverter-voltage influence on the overall performance of the PV system.

Storage-Less and Converter-Less Photovoltaic Energy Harvesting With Maximum Power Point Tracking for Internet of Things

Abstract: Energy harvesting from natural environment gives range of benefits for the Internet of things. Scavenging energy from photovoltaic (PV) cells is one of the most practical solutions in terms of power density among existing energy harvesting sources. PV power systems mandate the maximum power point tracking (MPPT) to scavenge the maximum possible solar energy. In general, a switching-mode power converter, an MPPT charger, controls the charging current to the energy storage element (a battery or equivalent), and the energy storage element provides power to the load device. The mismatch between the maximum power point (MPP) current and the load current is managed by the energy storage element. However, such architecture causes significant energy loss (typically over 20%) and a significant weight/volume and a high cost due to the cascaded power converters and the energy storage element. This paper pioneers a converter-less PV power system with the MPPT that directly supplies power to the load without the power converters or the energy storage element. The proposed system uses a nonvolatile microprocessor to enable an extremely fine-grain dynamic power management in a few hundred microseconds. This makes it possible to match the load current with the MPP current. We present detailed modeling, simulation, and optimization of the proposed energy harvesting system including the radio frequency transceiver. Experiments show that the proposed setup achieves an 87.1% of overall system efficiency during a day, 30.6% higher than the conventional MPPT methods in actual measurements, and thus a significantly higher duty cycle under a weak solar irradiance.