Load Static Models for Conservation Voltage Reduction in the Presence of Harmonics

The Conservation Voltage Reduction (CVR) is a technique that aims to achieve the decrease of power consumption as a result of voltage reduction. The customer is supplied with the lowest possible voltage level compatible with the stipulated level by the regulatory agency. International Standards ANSI C84.1-2006 and IEEE std 1250-1995 specify the range of supply voltage to electronics equipment from 0.9 to 1.05 pu of nominal voltage. To analyse the CVR effect in distribution systems with different load characteristics (residential, commercial, industrial or a combination of these), mathematical load models are used. Typically, these equipment/load models are used to analyse load aggregation without any consideration of its nonlinearity characteristics. Aiming to analyse the nonlinear characteristics and its consequences, this paper presents a discussion of the neglected variables as well as the results of a set of measurements of nonlinear loads. Different mathematical models are applied to obtain them for each load. Using these models the load aggregation is evaluated. It is presented that although the models show adequate results for individual loads, the same does not occur for aggregated models if the harmonic contribution is not considered. Consequently, to apply the load model in CVR it is necessary to consider the harmonics presence and the model has to be done using only the fundamental frequency data. The discussion about the causes is done and the models are compared with the measurements.

Output Voltage Ripple (OVR) Reduction of Boost Converter Using Particle Swarm Optimization

KY Boost Converter, a modern invention in the field of non-isolated DC-DC boost converter is identified for minimum voltage ripple. KY boost converter is the com- bination of KY converter and traditional boost converter. Such a converter has con- tinuous input and output inductor current, different from the traditional boost con- verter. And hence this converter is very suitable for very low-ripple applications. The Particle Swarm Optimization (PSO) based controller, FUZZY based controller and open loop KY boost converter are designed in MATLAB/Simulink model. The simu- lated results show a reduction in output ripple from 1.18 V of the existing open loop KY boost converter output to 0.54 V in the FUZZY logic controlled converter out- put. Further reduction in output ripple to 0.29 V is achieved in the proposed PSO based converter. The simulated results also show the variation of switching pulses based on the different existing and proposed method.

Voltage reduction of 808 nm GaAsP/(Al)GaInP laser diodes with GaInAsP intermediate layer

Ga In As P layers and Ga As P/（Al） Ga In P laser diodes（LDs） have been grown on Ga As substrates by metalorganic chemical vapor deposition. The Ga In As P layer, which is lattice matched to Ga As, has an intermediate band gap between Ga0.5In0.5P and Ga As. The Ga In P/Ga As heterojunction spikes, especially in the valence band,can be suppressed by introducing this thin Ga In As P layer into the heterostructure interface. The 808 nm Ga As P/（Al）Ga In P LDs with Ga In As P intermediate layer show a reduced operating voltage compared to the conventional LDs with abrupt Ga In P/Ga As interface due to the enhanced hole injection. As a result, the power conversion efficiency is improved from 52% to 60% at 350 m W output power. At high current injection, the LD with Ga In As P intermediate layer has higher light power owing to the decreased joule heating.

Load Shedding and Restoration for Intentional Island with Renewable Distributed Generation

Due to the high penetration of renewable distributed generation(RDG),many issues have become conspicuous during the intentional island operation such as the power mismatch of load shedding during the transition process and the power imbalance during the restoration process.In this paper,a phase measurement unit(PMU)based online load shedding strategy and a conservation voltage reduction(CVR)based multi-period restoration strategy are proposed for the intentional island with RDG.The proposed load shedding strategy,which is driven by the blackout event,consists of the load shedding optimization and correction table.Before the occurrence of the large-scale blackout,the load shedding optimization is solved periodically to obtain the optimal load shedding plan,which meets the dynamic and steady constraints.When the blackout occurs,the correction table updated in real time based on the PMU data is used to modify the load shedding plan to eliminate the power mismatch caused by the fluctuation of RDG.After the system transits to the intentional island seamlessly,multi-period restoration plans are generated to optimize the restoration performance while maintaining power balance until the main grid is repaired.Besides,CVR technology is implemented to restore more loads by regulating load demand.The proposed load shedding optimization and restoration optimization are linearized to mixed-integer quadratic constraint programming(MIQCP)models.The effectiveness of the proposed strategies is verified with the modified IEEE 33-node system on the real-time digital simulation(RTDS)platform.

Energy Savings Estimation of a Distribution System in Presence of Intelligent Volt-VAr Control Based on IEEE Std.1547-2018

In the present scenario,many solar photovoltaic(SPV)systems have been installed in the distribution network,most of them are operating at the unity power factor,which does not provide any reactive power support.In future distribution grids,there will be significant advances in operating strategies of SPV systems with the introduction of smart inverter functions.The new IEEE Std.1547-2018 incorporates dynamic Volt/VAr control(VVC)for smart inverters.These smart inverters can inject or absorb reactive power and maintain voltages at points of common coupling(PCCs)based on local voltage measurements.With multiple inverter-interfaced SPV systems connected to the grid,it becomes a necessary task to develop local,distributed or hybrid VVC algorithms for maximization of energy savings.This paper aims to estimate substation energy savings through centralized and decentralized control of inverters of SPV system alongside various VVC devices.Control strategies of each SPV inverter have been accomplished in compliance with IEEE Std.1547-2018.Time-series simulations are carried out on the modified IEEE-123 node test system.By utilizing smart inverters in traditional SPV systems,considerable energy savings can be obtained.These savings can be further increased by incorporating optimal intelligent VVC characteristics(IVVCC).Results show that just by allowing smart inverters on a predefined IVVCC(as per IEEE Std.1547-2018),a reduction of 11.69%in reactive demand and 5.63%in active demand have been acquired when compared with a conventional SPV system.Reactive energy demand is additionally reduced to 48.42%by considering centralized control of VVC devices alongside optimal IVVCC.

Fuzzy stochastic long-term model with consideration of uncertainties for deployment of distributed energy resources using interactive honey bee mating optimization

This paper presents a novel modified inter- active honey bee mating optimization （IHBMO） base fuzzy stochastic long-term approach for determining optimum location and size of distributed energy resources （DERs）. The Monte Carlo simulation method is used to model the uncertainties associated with long-term load forecasting, A proper combination of several objectives is considered in the objective function. Reduction of loss and power purchased from the electricity market, loss reduc- tion in peak load level and reduction in voltage deviation are considered simultaneously as the objective functions. First, these objectives are fuzzified and designed to be comparable with each other. Then, they are introduced into an IHBMO algorithm in order to obtain the solution which maximizes the value of integrated objective function. The output power orDERs is scheduled for each load level. An enhanced economic model is also proposed to justify investment on DER. An IEEE 30-bus radial distribution test system is used to illustrate the effectiveness of the proposed method.