Abstract-More than 1.3 billion people in the world lack access to electricity and this energy poverty is a major barrier to human development. This paper describes a new concept of peer-to-peer electricity sharing which creates a marketplace for electricity. In this marketplace, the people who can afford power generating sources such as solar panels can sell electricity to people who are unable to afford generating sources or who might have access to electricity but require more electricity at certain times. These adhoc microgrids created by sharing of resources provide affordable electricity and are enabled by a Power Management Unit (PMU) described in this paper.
Ad hoc electrical networks are formed by connecting power sources and loads without pre-determining the network topology. These systems are well-suited to addressing the lack of electricity in rural areas because they can be assembled and modified by non-expert users without central oversight. There are two core aspects to ad hoc system design: 1) designing source and load units such that the microgrid formed from the arbitrary interconnection of many units is always stable and 2) developing control strategies to autonomously manage the microgrid (i.e., perform power dispatch and voltage regulation) in a decentralized manner and under large uncertainty. To address these challenges we apply a number of nonlinear control techniques-including Brayton-Moser potential theory and primal-dual dynamics-to obtain conditions under which an ad hoc dc microgrid will have a suitable and asymptotically stable equilibrium point. Further, we propose a new decentralized control scheme that coordinates many sources to achieve a specified power dispatch from each. A simulated comparison to previous research is included.
Abstract-This paper presents a new topology for a high efficiency dc/dc resonant power converter that utilizes a resistance compression network to provide simultaneous zero voltage switching and near zero current switching across a wide range of input voltage, output voltage and power levels. The resistance compression network (RCN) maintains desired current waveforms over a wide range of voltage operating conditions. The use of on/off control in conjunction with narrowband frequency control enables high efficiency to be maintained across a wide range of power levels. The converter implementation provides galvanic isolation and enables large (greater than 1:10) voltage conversion ratios, making the system suitable for large step-up conversion in applications such as distributed photovoltaic converters. Experimental results from a 200 W prototype operating at 500 kHz show that over 95% efficiency is maintained across an input voltage range of 25 V to 40 V with an output voltage of 400 V. It is also shown that the converter operates very efficiently over a wide output voltage range of 250 V to 400 V, and a wide output power range of 20 W to 200 W. These experimental results demonstrate the effectiveness of the proposed design.
We assess the effects that size and locations of photovoltaic (PV) arrays in a low-voltage (LV) electric power grid have on the maximum installable capacity. The objective is to place and control PVs without violating voltage limits and not require interventions by utilities. Multi-modal control is suggested whereby the PVs deviate from unity power factor and begin to supply reactive power if the voltage limits are approached; the installed capacity need not ever be disconnected. Given such multi-modal control, it is shown that the best location of a large PV farm is at the load located furthest away from the medium voltage step-down transformer. Furthermore, we show that the maximum installable capacity increases if the capacity is distributed as many smaller "rooftop" PVs.
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