Backup Generators Research Articles

The practicality of distributed PV-battery systems to reduce household grid reliance

The advent of low-cost solar photovoltaics (PV) and battery electricity storage has the potential to bring about fundamental shifts in the structure of the power sector in the United States. We analyze how PV-battery systems of various sizes could reduce the dependence of residential customers on the central grid and their impact on CO2 emissions. We further analyze how the costs of such systems change as customers attempt to decrease their dependence on the grid, considering the installed cost of PV-battery systems and the cost of electricity under a net-energy metered rate structure. We analyze these relationships for residential customers in five locations across the U.S. We find that fully disconnecting from the grid with a PV-battery system is impractical for most residential customers without also having dispatchable backup generation. Finally, we estimate how the economics of behind-the-meter PV-battery systems may change if the costs of PV systems continue to fall.

A Comparative Case Study of Remote Area Power Supply Systems Using Photovoltaic-battery vs Thermoelectric-battery Configuration

Abstract The paper presents a comparative study of two types of remote area power supply (RAPS) systems, which are the existing photovoltaic-based (PV) configuration and the proposed thermoelectric-based (TE) configuration. Both RAPS systems are solar-based power generators and sized according to Melbourne weather conditions (latitude 37.5 o S). In this study, the RAPS system designs for both PV and TE have no backup generator and the batteries are the only device for electrical energy storage. Battery storage is used for storing solar energy during the available days for meeting the energy demand as required. The presented RAPS systems for this comparative study are PV/Battery and TE/Battery configurations. Generally, both PV and TE cells are solar-based power generating cells but they have different pre-conversion inputs. For electrical power generation, PV uses sunlight as input energy while the TE uses concentrated solar heat. The results show that the total setup cost for TE/Battery system is 66% higher than PV/Battery system under similar design requirements. Despite having higher setup cost, the TE/Battery system has the potential to harness both electrical and thermal energy for domestic purposes.

Frequency control by variable speed wind turbines in islanded power systems with various generation mix

This study presents the impact on power system frequency control in small power systems based on different generator topologies with a large penetration (50%) of variable speed wind turbines. The impact of a proposed controller is investigated versus various wind speeds. In particular, wind speeds with an average wind speed just below rated wind speed proves to cause the worst frequency fluctuations regardless of the type of backup generation topology investigated during 50% wind-penetration ratio. For this wind-speed session and a hydro-based system, the proposed control system improves the frequency duration outside of the specified range [49.9, 50.1]Hz from 81 to 53% while reducing its delivered energy by only 6%. Furthermore, the proposed control reduces the absolute value of requested reserve by 49% from the hydro unit responsible for primary frequency control.

Flexibility evaluation of integrating solar power into the Nigerian electricity grid

The study evaluated the capability of current thermal generation to back-up variation generation from solar energy penetration into the Nigerian power grid from a system operation perspective using security constraint unit commitment model. This provides an empirical evidence of the impacts that can tip the balance towards a sustainable future low carbon electricity mix. Through 10 and 20% solar energy penetration scenarios, greenhouse reduction of 1975.70 and 3590.03 lb/day, respectively, can be achieved. However, daily peak-valley net demand difference to be supplied by the thermal plants will increase from 702.5 to 857.5 and 1607.5 MW, numbers of daily start-up will increase from 23 to 30 and 25, daily system spinning reserve will increase from 723 to 757 and 815 MW and daily idle hours of the thermal plants will increase from 52 to 71 and 72 h, in a 10 and 20% solar energy integrated system, respectively. The daily operational revenue of the thermal plants will also reduce by 5.5 and 7.9% in a 10 and 20% solar energy integrated system, respectively. These are useful data in developing policy framework for the future electricity market as the country diversify her energy source and mitigate greenhouse effect.

Incidence of dog bite in rural area (Chountra), District Rawalpindi, Province Punjab, Pakistan

Pakistan is a developing country having huge burden of communicable disease, now having ever increasing number of non-communicable disease cases. This combine burden of communicable and non-communicable disease is over stretching already scarce health resources. The objective of this study was to accesses the incidence of dog bite in Chountra, District Rawalpindi, Province Punjab, Pakistan. This is descriptive study conducted on medical record of dog bite cases between 2011 and 2013. Total numbers of cases were 150. Most of the cases were registered during summer especially in the months of May to August. Most of the victims were male and found to be more common in children. The commonest site of the dog bite was lower limb. Vaccine availability was 60-70%. For cold chain management of vaccine, the backup generator was in working condition in 75-85% of the times but fuel availability was relatively low around 50-60%. To conclude, in rural setup of Pakistan dog bite cases are considerably high and impose significant burden on health service despite the fact that it is preventable.

Optimization and Evaluation of Hybrid PV/WT/BM System in Different Initial Costs and LPSP Conditions

A modelling and optimization study was performed to manage energy demand of a faculty in Karabuk University campus area working with a hybrid energy production system by using genetic algorithm (GA). Hybrid system consists of photovoltaic (PV) panels, wind turbines (WT) and biomass (BM) energy production units. Here BM is considered as a back-up generator. Objective function was constituted for minimizing total net present cost (TNPC) in optimization. In order to obtain more accurate results, measurements were performed with a weather station and data were read from an electricity meter. The system was also checked for reliability by the loss of power supply probability (LPSP). Changes in TNPC and localized cost of energy (LCOE) were interpreted by changing LPSP and economic parameters such as PV investment cost, WT investment cost, BM investment cost, and interest rates. As a result, it was seen that a hybrid system consisted of PV and BM associated with an effective flow algorithm benefited from a GA meets the energy demand of the faculty.

Rightsizing Generators Through Harmonic Mitigation Realizes Energy, Emissions, and Infrastructure Reductions

Sizing prime and backup generator packages for nonlinear loads (such as adjustable speed drives (ASDs), solid-state uninterruptible power system, dc drives, and other SCR loads and even single phase loads, such as computer systems, ballasted lighting, and other power electronic loads) is not a simple process. Including the effects of the nonlinear load harmonics is essential to properly sizing generator capacity. Incorrectly calculating the harmonic current contribution can result in significantly undersizing the generator leading to brownout conditions, overloading of the generator, nuisance tripping, misoperation of the automatic voltage regulator, generator failures, and load equipment damage through elevated voltage distortion. However, oversizing the generator to accommodate the nonlinear load current harmonics will result in increased initial installation costs, much higher fuel and operating costs due to poor operating efficiencies and higher emissions. In an oil pipeline islanded pumping application, the problems experienced with the adjustable speed drive operation on a 200 hp pump led to the generator being significantly upsized. Not until harmonic mitigation was finally considered though, did the ASD and generator operate without issues. Computer simulations were used to demonstrate how the application of a passive wide spectrum harmonic filter would reduce the ASD harmonic currents to eliminate the voltage distortion and allow the operator to retrofit the installation with a more properly sized generator that provided energy/fuel savings and emissions reduction while maintaining good power quality.

A novel boost four-leg converter for electric vehicle applications

Integrating the electric vehicle into grid or microgrid has been receiving more and more attention in recent years. Typically, the electric vehicle (EV) chargers with their power batteries have been developed for vehicle-to-home(V2H) applications, acting as a backup generation to supply emergency power directly to a home. Traditional EV chargers in V2H applications mainly consist of DC/DC and DC/AC stages, which complicate the control algorithm and result in low conversion efficiency. In order to solve this problem, a novel EV charger is proposed for V2H applications. It can boost the battery voltage and output AC voltage with only one-stage power conversion. Also, the DC, 1-phase and 3-phase loads can be fed with the proposed single-stage EV charger. The system control strategy is also provided to deal with versatile load variations. Finally, the performance evaluation results verify the effectiveness of the proposed solution.

Quantifying Variability for Grid-connected Photovoltaics in the Tropics for Microgrid Application

This paper quantifies the variability of solar resource for PV systems located in the tropical climate. Global horizontal irradiance data is obtained from a site in Melaka, Malaysia with one-minute-average values for a full year. Clearness index and variability index are used together with a clear sky model for tropical location to classify the days according to its fluctuation profile. The results show that significant amount of variability occur throughout the year for this site while days with clear skies are almost negligible. PV can potentially supply part of the loads during the day but precise planning on storage and backup generators is crucial for independent microgrid operation.

A Unified Seamless Transfer Control Scheme for Grid-Connected and Islanding Modes of Operation of Grid- Connected PV System

Objectives: This paper proposes a concept of micro-grid under smart distribution environment conditions with distributed generation resources like solar, wind etc. Methods/ Statistical Analysis: In present scenario, the importance of distribution sources is very high for maintaining the system reliability and also for providing backup generation under islanding condition and also as well as in grid-connected conditions. Findings: In this paper, a new control concept has been proposed for the seamless transfer who is based on Phase-Locked Loop (PLL) control for islanding and grid connected modes. In this paper the phase locked loop is used to maintain phase synchronization between grid and load voltages under grid and islanding conditions. And also, this paper proposes a current and voltage controller for stability analysis. The proposed method interfaces the PV system to the grid effectively. This proposed system is implemented and verified by using Matlab/Simulink. Applications/ Improvement: The proposed architecture is greatly beneficial for practical implementation of standalone and Islanded hybrid systems.

Distributed Generation Operation in Micro-Grid by using Smart Distribution Systems

Objectives: This paper proposes a concept of micro-grid under smart distribution environment conditions with distributed generation resources like solar, wind and fuel etc. Methods: In present scenario, the importance of distribution sources is very high for maintaining the system reliability and also for providing backup generation under islanding condition and also as well as in grid-connected conditions. Findings: For meeting these limitations this paper proposes a new control structure called power-voltage- current controller. Basically, the main aim of these controller is to provide flexible and robust distributed generation operation control characteristics such as (a) control of active/reactive power (PQ) and dynamic power/voltage (PV) in grid connected mode. (b) To provide regulated power under micro-grid. (c) For providing smooth transients between islanding and grid-connected modes and (4) finally, this controller also concentrates on reduction of distortions/harmonics in proposed system which is caused by heavily non-linear loading conditions. Applications: The proposed architecture is greatly beneficial for practical implementation of standalone and Islanded hybrid systems.

Analysis of Photovoltaic Self-Consumption Systems

Components and installation prices could make the self-consumption of solar photovoltaic (PV) systems competitive. In this paper, we explore different self-consumption options, off-grid PV systems (with back-up generator and/or batteries), and grid-connected PV systems under net-metering policies. The calculation of the net present cost (NPC) reveals that the grid-connected PV-only case (for the net-metering scheme) is the most attractive from the technical and financial points of view, with a levelised cost of energy less than 0.1 €/kWh. Off-grid PV + Diesel + Batteries has a higher cost, around two or three times the grid-connected PV-only under net metering. Additionally, the off-grid PV + Diesel is less attractive from a financial point of view, which has a cost of around 10 times the PV-only under net metering. In addition, the values of life cycle CO2 emissions in each of the cases studied have been compared, and we have concluded that although the off-grid PV + Diesel + Batteries system presents lower CO2 emissions than the PV-only system, the existence of batteries does not allow one to affirm that the PV + Diesel + Batteries system is the best from an environmental point of view.

Influence of winter North-Atlantic Oscillation on Climate-Related-Energy penetration in Europe

When considering 100% renewable scenarios, backup generation is needed for stabilizing the network when Climate Related Energy (CRE) such as wind, solar or run-of-the river hydropower are not sufficient for supplying the load. Several studies show that, over relatively short time period (less than 10 years), backup generation needs are reduced by dissipating power densities either in space through grids or time through storage. This study looks at the impact of low time frequency variations of CRE with a specific focus on the time variability induced by the North Atlantic Oscillation (NAO) teleconnection pattern during winter season. A set of eleven regions in Europe and Tunisia is used for highlighting space variability of the winter NAO’s impact. For each of these regions, we combine data from the Weather Research and Forecasting Model and the European Climate Assessment & Dataset for estimating solar-power, wind-power, run-of-the-river hydro-power and the energy load over the 1980–2012 time period. Results show that NAO’s impact on winter penetration rate depends on both the considered energy source and the location. They also highlight a non-linear relation between the NAO’s impact on CRE penetration rates and the level of equipment used for harvesting the CRE sources.

Increasing the availability and quality of caesarean section in Tanzania.

To describe the results of increasing availability and quality of caesarean deliveries and anaesthesia in rural Tanzania. Before-after intervention study design. Rural Tanzania. Ten health centres located in rural areas were upgraded to provide comprehensive emergency obstetric care (CEmOC) and the four related district hospitals were supported. Upgrading entailed constructing and equipping maternity blocks, operation rooms and laboratories; installing solar systems, backup generators and water supply systems. Associate clinicians were trained in anaesthesia and in CEmOC. Mentoring and audit of reasons for caesarean section (CS) and maternal deaths were carried out. Measures of interest were compared using analysis of variance (ANOVA) statistical tests. Trends in CS rates, proportion of unjustified CS, use of spinal anaesthesia, and the risk of death from complications related to CS and anaesthesia. During the audit period (2012-2014), 5868 of 58 751 deliveries were by CS (10%). The proportion of CS considered to be unjustified decreased from 30 to 17% in health centres (P=0.02) and from 37 to 20% in hospitals (P<0.001). Practice of spinal anaesthesia for CS increased from 10% to 64% in hospitals (P<0.001). Of 110 maternal deaths, 18 (16.4%) were associated with complications of CS, giving a risk of 3.1 per 1000 CS; three (2.7%) were judged to be anaesthetic-associated deaths with a risk of 0.5 per 1000 caesarean deliveries. Increasing availability and quality of CS by improving infrastructure, training and audit of reasons for CS is feasible, acceptable and required in low resource settings. Increasing availability and quality of CS in rural Africa is feasible.

Performances analysis of WT-DFIG with PV and fuel cell hybrid power sources system associated with hydrogen storage hybrid energy system

This paper highlights the modeling and the simulation of a micro-grid renewable power system. It comprises wind turbine (WT) doubly fed induction generators (DFIGs), photovoltaic generator (PV), a proton exchange membrane (PEM) fuel cell (FC) generator, a water electrolyzer used for long-term storage, a Hydrogen tank, and a battery bank (BB) utilized for short-term storage. Based on the given configuration and the different characteristics of the main components in the micro-grid, an overall control and a power management strategy are proposed for this system. This strategy consists in charging the BBs and producing hydrogen from the water electrolyzer in the case of excess power from the WT-DFIGs and PV generators. Therefore, the FC and the BBs will be used as a backup generator to supply the demand required power, when the WT-DFIGs and the PV energy are deficient. The effectiveness of this contribution is verified through computer simulations, where very satisfactory results are obtained.

Microscale air quality impacts of distributed power generation facilities

ABSTRACTThe electric system is experiencing rapid growth in the adoption of a mix of distributed renewable and fossil fuel sources, along with increasing amounts of off-grid generation. New operational regimes may have unforeseen consequences for air quality. A three-dimensional microscale chemical transport model (CTM) driven by an urban wind model was used to assess gaseous air pollutant and particulate matter (PM) impacts within ~10 km of fossil-fueled distributed power generation (DG) facilities during the early afternoon of a typical summer day in Houston, TX. Three types of DG scenarios were considered in the presence of motor vehicle emissions and a realistic urban canopy: (1) a 25-MW natural gas turbine operating at steady state in either simple cycle or combined heating and power (CHP) mode; (2) a 25-MW simple cycle gas turbine undergoing a cold startup with either moderate or enhanced formaldehyde emissions; and (3) a data center generating 10 MW of emergency power with either diesel or natural gas-fired backup generators (BUGs) without pollution controls. Simulations of criteria pollutants (NO2, CO, O3, PM) and the toxic pollutant, formaldehyde (HCHO), were conducted assuming a 2-hr operational time period. In all cases, NOx titration dominated ozone production near the source. The turbine scenarios did not result in ambient concentration enhancements significantly exceeding 1 ppbv for gaseous pollutants or over 1 µg/m3 for PM after 2 hr of emission, assuming realistic plume rise. In the case of the datacenter with diesel BUGs, ambient NO2 concentrations were enhanced by 10–50 ppbv within 2 km downwind of the source, while maximum PM impacts in the immediate vicinity of the datacenter were less than 5 µg/m3.Implications: Plausible scenarios of distributed fossil generation consistent with the electricity grid’s transformation to a more flexible and modernized system suggest that a substantial amount of deployment would be required to significantly affect air quality on a localized scale. In particular, natural gas turbines typically used in distributed generation may have minor effects. Large banks of diesel backup generators such as those used by data centers, on the other hand, may require pollution controls or conversion to natural gas-fired reciprocal internal combustion engines to decrease nitrogen dioxide pollution.

Implementation of the ANISA Study in Karachi, Pakistan: Challenges and Solutions.

Aetiology of Neonatal Infection in South Asia (ANISA) is a multicenter study in Bangladesh, India and Pakistan exploring the incidence and etiology of neonatal infections. A periurban site in Karachi was selected for its representativeness of the general population in neonatal health indicators. An established demographic surveillance system and other infrastructure needed for conducting the study already existed at this site. ANISA presents a unique challenge because of the need to capture every birth outcome in the community within a few hours of delivery to reliably estimate the incidence and etiology of early-onset sepsis in a setting where home births and deaths are common. Major challenges at the Karachi site are related to early birth reporting and newborn assessment for births outside the catchment areas, parental refusal to participate, diverse ethnicity of the population, collection of biological specimens from healthy controls, political instability and crime, power outages and blood culture contamination. Some of the remedial actions taken include prolonging working hours; developing counseling skills of field workers; hiring staff with different linguistic abilities from within the study community; liaising with health facilities, key community informants, Lady Health Workers and traditional birth attendants; hiring community mobilizers; enhancing community sensitization; developing contingency plans for field work interruptions and procuring backup generators. The specimen contamination rate has decreased through training, supervision and video monitoring of blood collection procedures with individualized counseling of phlebotomists. ANISA offers lessons for successful implementation of complex study protocols in areas of high child mortality and challenging social environments.

Get rid of it: To what extent might improved reliability reduce self-generation in Nigeria?

Despite the global concerns surrounding the threats of climate change to both human health and sustainable environments, gasoline- or diesel-powered generators with non-negligible emissions have become a popular choice among Nigerian households due to the poor publicly provided electricity. This study examines the extent to which an improvement in publicly supplied electricity may reduce backup generation and, by implication, reduce emissions from Nigerian homes. The results from a random-effects probit analysis reveal that, although improved electricity service quality would significantly reduce self-generation, self-generation would continue in the country, especially among rich and educated households. The study concludes by highlighting the policy implications of the findings.

Bacterial population profiling from diesel obtained from fuel stations

Microbial growth develops in stored diesel fuel. This can influence later use in emergency backup generators and vehicles through the clogging of fuel filters by the development of biomass. A mutualistic microbial community can develop in stored fuel products that degrade polycyclic aromatic hydrocarbons to the benefit of one another. This project aimed to study the bacterial community profile of diesel obtained from commercial fuel stations using culture dependent and independent methods. Bacteria and total DNA were isolated from the diesel and the community was studied using denaturing gradient gel electrophoresis of the 16S rDNA region. This resulted in the isolation of six bacterial species from two different genera (related to Bacillus and Lysinibacillus) that could grow in pure culture with diesel as carbon source. The denaturing gradient gel electrophoresis analysis indicated the occurrence of an additional eight genera in the sampled diesel. Both methods identified bacteria related to Bacillus pumilus occurring in the samples. Bacillus pumilus was the predominant species (50%) isolated from diesel samples using culture media. The identification of bacteria occurring in commercial diesel samples can be useful in determining the degree of degradation occurring during the storage of the product and also possible bioremediation agents in diesel fuels spills.

Lithium‐ion battery modelling for the energy management problem of microgrids

This study presents a mathematical model of lithium-ion (Li-ion) batteries in the energy management (EM) problem of a microgrid (MG). In this study, the authors develop a detailed model of Li-ion batteries that considers the degradation cost associated with operation, controllable and uncontrollable charging ramps, other limits, and the operating characteristics provided by the manufactures. The Li-ion battery degradation cost is analysed using different approaches and is compared with modelling without this cost, using a quadratic degradation cost, and using a piecewise degradation cost. Furthermore, this cost is analysed using a linear cost that takes the life expectancy based on the number of cycles of the battery into account. To analyse the proposed method and other modelling approaches, the authors examine the battery model in an EM problem in an MG. This MG, which can be connected to the main grid, also uses wind and photovoltaic as generation resources, in addition to a backup generator. The EM problem is modelled as a deterministic mixed-integer linear (or quadratic) problem; the results of eleven different cases are used in the analysis of the proposed Li-ion battery model for a 24 h planning horizon.