Showing papers presented at "IEEE International Conference on Power Engineering, Energy and Electrical Drives in 2015"

Condition monitoring for DC-link capacitors based on artificial neural network algorithm

Abstract: In power electronic systems, capacitor is one of the reliability critical components. Recently, the condition monitoring of capacitors to estimate their health status have been attracted by the academic research. Industry applications require more reliable power electronics products with preventive maintenances. However, the existing capacitor condition monitoring methods suffer from either increased hardware cost or low estimation accuracy, being the challenges to be adopted in industry applications. New development in condition monitoring technology with software solutions without extra hardware will reduce the cost, and therefore could be more promising for industry applications. A condition monitoring method based on Artificial Neural Network (ANN) algorithm is therefore proposed in this paper. The implementation of the ANN to the DC-link capacitor condition monitoring in a back-to-back converter is presented. The error analysis of the capacitance estimation is also given. The presented method enables a pure software based approach with high parameter estimation accuracy.

Automotive waste heat harvesting for electricity generation using thermoelectric systems — An overview

Abstract: Majority of the vehicles commercially available today and on the roads today use internal combustion engines (ICE) for the power source. Such engines utilize only small share of the fuel primary energy converted to kinetic energy, however majority of fuel primary energy is wasted while dissipated in the ambient air as waste heat or as hot exhaust gas. A remarkable potential for improving the efficiency of the ICE systems lies in the recovery of the energy wasted today. This paper presents an overview of the state of the art of current research of exhaust waste heat recovery systems utilizing thermoelectric generators (TEGs). Such systems provide the direct heat-to-electric energy conversion and allow building the exhaust energy recovery systems without adding moving parts to the vehicles. The review will present the overview related particularly to vehicle engines exhaust energy recovery systems, introducing the key parameters, components and factors that determine the performance of such systems.

Detection of stator winding fault in induction motors using a motor square current signature analysis (MSCSA)

Abstract: In this paper the short-circuit fault inter-turn on the stator of an induction motor is analysed by an online diagnostic method. For the diagnostic method it is proposed the motor square current signature analysis (MSCSA). This method uses the results of spectral analysis of the instantaneous square stator current. The effects of stator square current spectrum are described and the related frequencies determined. This method is similar to the instantaneous power signature analysis, however has the advantage of just require one current sensor. Several simulation and experimental results are presented in order to illustrate the characteristics of the proposed method.

A new predictive control scheme for a VSI with reduced common mode voltage operating at fixed switching frequency

Abstract: Traditional finite-set model predictive control (FS-MPC) techniques are characterized by a variable switching frequency which causes noise as well as large voltage and current ripple. In this paper a novel predictive control strategy with a fixed switching frequency for a voltage source inverter is proposed, with the aim of obtaining a modulated waveform at the output of the converter with a natural reduction of the common mode voltage. The feasibility of this strategy is evaluated using simulation results to demonstrate the advantages of predictive control, such as fast dynamic response and the easy inclusion of nonlinearities and they are compared with the modulated model predictive control (M2PC) proposed recently.

Supraharmonics (2 to 150 kHz) and multi-level converters

Abstract: This paper summarizes the state of part of the discussions in CIGRE/CIRED/IEEE joined working group C4.24, especially where it concerns supraharmonics. There is an increasing interest from the international standard-setting community in knowledge about distortion in the frequency range 2 to 150 kHz, referred to as supraharmonics. The reduction of emission in the lower-frequency ranges appears to result in an increase in supraharmonic emission by equipment. Power electronics has emerged as a ubiquitous technology, which plays a critical role in almost any areas. Power electronics converter is an important source of waveform distortion, but, as shown in this paper, power electronics can also be the key to mitigate distortion, when the proper technology is employed.

Single-switch galvanically isolated quasi-Z-source DC-DC converter

Abstract: A novel galvanically isolated quasi-Z-source DC-DC converter with a single switch is presented It is derived from the conventional single-switch nonisolated quasi-Z-source DC-DC converter The new topology is within the transformer based class of the galvanically isolated impedance-source DC-DC converters, while existing topologies are solely within the coupled inductor based class This simple solution features low cost, high efficiency and reliability that suits low power or low-voltage applications Theoretical predictions were verified with simulation in PSIM and experimentally with a 200 W prototype The topology is further improved using the combined energy transfer principle

Analysis and prediction of electricity consumption using smart meter data

Abstract: This paper is considering application of smart meter data to predict electricity consumption of household consumers. The availability and amount of data is suitable for in-depth statistical analysis of electricity consumption profiles and the study of consumer's behavior. Prediction of electricity consumption is very important for electricity traders to balance their electricity purchase and sales portfolio, as well as to prepare optimal price products (offers) for their clients. Electricity consumption data of 500 consumers divided into 6 consumers groups was analyzed. The consumption data was derived from smart meters. As the next step, modern methods of electricity consumption forecasts would be applied to predict household electricity consumption.

System problems of power supply reliability analysis formalisation

Abstract: The parameters and indicators of the systems of electric supply for consumers are necessary to be permanently specified for the prognosis, estimation and monitoring of their reliability. In this connection the basic system problems of the electric supply reliability maintenance and improvement are considered in this paper. The responsibility of the designers, technical and administrative personnel should be improved while the tasks of electric supply of the consumers are solved.

Future control architecture and emerging observability needs

Abstract: The paper presents the first findings from workpackage "Increased Observability" in EU FP7 project ELECTRA. Accommodation of intermittent generation into the network and its reliable operation require a gradual evolution of the network structure and in particular improvement of its monitoring or observing. The present practices of observing distribution networks are quite limited and vary from country to country. New network architectures are expected to evolve in the close future, including web-of-cells (concept defined in ELECTRA), which will result in new control schemes, significantly different from the existing. Several new observability needs have to be met in order to secure operation of the future networks.

Modulated model predictive control (M 2 PC) with fixed switching frequency for an NPC converter

Abstract: Advances in power electronic converters technology along with the wide range of applications require sophisticated digital control schemes In the recent years Finite Control Set Model Predictive Control (FCS-MPC) has been successfully proposed as an alternative to the traditional control techniques, due to its fast dynamic response, easy inclusion of nonlinearities and constraints in the control algorithm and the ability of incorporate several control requirements in one cost function However, FCS-MPC is characterized by a variable switching frequency which can cause a degradation in system performance, or demand higher output filtering In this paper a Modulated Model Predictive Control (M2PC) strategy is proposed for constant switching frequency operation and verified with a neutral-point-clamped (NPC) converter for load current regulation and DC-link capacitor voltages balancing The aim of this control technique is to obtain a modulated waveform at the output of the converter, whilst maintaining all the desired characteristics of FCS-MPC The feasibility of this strategy is evaluated using simulation and compared to the classical FCS-MPC strategy

Design and dynamic study of a 6 kW external rotor permanent magnet Brushless DC motor for electric drivetrains

Abstract: This paper studies electromagnetic and parametric design and performance analysis of an in-wheel out-runner BLDC (Brushless Direct Current) electric motor designed specifically for automotive applications. Typical design techniques and simulation studies are applied to the BLDC motor. Specifically, design specifications such as the number of turns, winding area, and stator pole height composing the stator structure are obtained and the performance characteristics of the motor are investigated using the finite element method (FEM). Also, the outputs in terms of phase inductances, flux linkages of each stator winding and static torques for different rotor positions are calculated and evaluated. Finally, a dynamical performance analysis is carried out by using a physical electromechanical model the BLDC motor.

Full soft-switching high step-up current-fed DC-DC converters with reduced conduction losses

Abstract: Two variants of the full soft-switching high step-up DC-DC converter are proposed. The main advantage of the converters is the minimized conduction losses by the use of the four-quadrant switches and a specific control algorithm. Simulation was performed to verify the principle of operation and to estimate the losses.

Forecasting hot water consumption in dwellings using artificial neural networks

Abstract: The electricity grid is currently transforming and becoming more and more decentralised. Green energy generation has many incentives throughout the world thus small renewable generation units become popular. Intermittent generation units pose threat to system stability so new balancing techniques like Demand Side Management must be researched. Residential hot water heaters are perfect candidates to be used for shifting electricity consumption in time. This paper investigates the ability on Artificial Neural Networks to predict individual hot water heater energy demand profile. Data from about a hundred dwellings are analysed using autocorrelation technique. The most appropriate lags were chosen and different Neural Network model topologies were tested and compared. The results are positive and show that water heaters have could potentially shift electric energy.

Bidirectional DC/AC energy flow measurement

Abstract: Bidirectional energy flow monitoring near 230 V AC or 600 V DC micro-grid consumers — industrial devices or household consumers — rise questions regarding measurement methods and devices self power consumption, price and precision. Article deals with overall 3×230V+N AC and 600V DC micro-grid bidirectional monitoring system design as well as measurement modules communication and data logging.

Trends of smart grids development as fostered by European research coordination: The contribution by the EERA JP on smart grids and the ELECTRA IRP

Abstract: Smart Grids play a central role in order to accommodate the levels of renewable energy sources penetration foreseen in the SET-Plan of the European Commission for the future “low-carbon” energy system. In the field of electricity grids the European Electricity Grid Initiative, the EERA JP on Smart Grids, and the ETP on Smart Grids coordinate their activity in order to promote the evolution of the present power system. This work summarizes their goals, objectives and activities, highlighting the existing links and interactions.

Utilising high and premium efficiency three phase motors with VFDs in a public water supply system

Abstract: The increased reliability and ultimately reduced life cycle cost of high and premium efficiency three phase motors in a process control application is discussed The reduced energy consumption of these motors is evaluated in a public water system case study under variable frequency conditions The importance of the consideration of a combined system, which includes variable speed control, motor and load — as opposed to only replacing with high efficiency motors for energy saving purposes — is practically observed and reported on The paper reports on the marginal improvement in energy consumption at reduced supply frequency for motor replacement only (not surprising) but a very impressive 46% saving in energy consumption by controlling pumped water at a reduced but constant delivery rate

Predictive control with imposed sinusoidal source and load currents of an indirect matrix converter operating at fixed switching frequency and without weighting factors

Abstract: In this paper a predictive control technique for an indirect matrix converter is proposed. The control strategy allows to impose a sinusoidal waveform in both the input and output current of the converter without any weighting factor in the controller and, at the same time, the operation at fixed switching frequency. Simulation results validate the proposal under both steady and transient states which are also compared with the predictive current control strategy with minimization of the reactive input power.

Optimal supercapacitor energy storage system sizing for traction substations

Abstract: In this paper authors present a method for optimal sizing of supercapacitor (SC) energy storage system (ESS) for braking energy recovery in tram network. The method is applicable for segmented tram networks with radial feeding topology and a stationary storage system installed in traction substation. The method is demonstrated for one traction substation of Riga public transport network.

Generating surface dynamometer cards for a sucker-rod pump by using frequency converter estimates and a process identification run

Abstract: This paper presents a novel method to generate surface dynamometer cards of a sucker rod pump by applying torque and rotational speed estimates of a variable speed induction motor drive and a pumping process identification run

Review of eccentricity fault detection techniques in IMs focusing on DFIG

Abstract: Induction machines are widely used in different applications. Unpredicted breakdown of these machines usually leads to costly downtime and repairs. These expenses can be minimized by using proper condition monitoring techniques. Eccentricity fault is one of the widespread faults causing machine malfunction; its detection could be useful for preventing of harmful consequences. In this paper, different works on eccentricity fault diagnosis of induction machines with different types of supply have been reviewed. Due to extensive use of induction machines in wind turbines (WT) as doubly-fed induction generator (DFIG), in addition to declaration of importance of eccentricity fault diagnosis in DFIG, detection of eccentricity fault in DFIG is also reviewed.

PLC-based hardware-in-the-loop simulator of a centrifugal pump

Abstract: A hardware-in-the-loop (HIL) model of a centrifugal pump is proposed. The HIL simulator consists of the pump and pipeline imitators built on the basis of the variable speed drives (VSD) connected via the programmable logical controller (PLC, and profibus communication components. The mathematical description of the pressure maintenance represents a core of the simulation methodology. To study the system, a series of tests have been conducted that proved the designed system flexibility and accuracy in pressure imitation at both the static and the dynamic modes.

A new approach to increase the integration of RES in a mediterranean island by using HTLS conductors

Abstract: Today, in many countries, it is very difficult to build new power lines, especially because of right of way authorization problems Furthermore, the production of electricity from renewable sources is growing more and more For these reasons Terna SpA (Italian TSO) has to take advantage of existing overhead transmission lines In order to increase the transmission capacity and the exportation of RES (Renewable Energy Sources) from Sicily to the mainland, the existing high-voltage power grid in Sicily has been studied and analysed by Neplan®, which is a powerful software tool able to analyze, plan, optimize and simulate electrical power grids This paper, after a description of existing power grid in Sicily and HTLS (High Temperature Low Sag) Conductors, shows how it is possible to increase the active power exportation from RES to the mainland, under certain load conditions during the summer and winter

Analysis of a reconfigurable Fibonacci switched capacitor converter with a multiphase balanced switching

Abstract: This paper investigates into enriching a (step-down) classic Fibonacci switched capacitor converter voltage target ratios set by applying a multiphase switching. Simple theoretical closed-form expressions for equivalent output resistances are obtained using charge flow balance analysis that also provides a useful insight into switched capacitor and output voltage ripples. It is shown that employing a balanced multiphase switching allows for essential switched capacitor and peak-to-peak output voltage ripple (or, alternatively, output filter capacitance) reduction.

Analysis of buck mode realization possibilities in quasi-Z-source DC-DC converters with voltage doubler rectifier

Abstract: A series resonant tank in the quasi-Z-source (qZS) DC-DC converter with a voltage doubler rectifier could significantly increase the input voltage regulation range by adding the buck mode realization possibility. This paper discusses two different control approaches of the qZS series resonant DC-DC converter in the buck mode: variable frequency control and phase shift modulation. Both methods are explained by means of steady-state analysis. To verify the theoretical background, a 200 W experimental prototype was built. Experimental results are compared with theoretical predictions.

Flexibility options of Riga CHP-2 plant operation under conditions of open electricity market

Abstract: Nowadays with commercialization of cogeneration business, expansion of electricity production and profit maximization are the main optimization criteria for power plants. That is why, the number of combined heat and power (CHP) plants in Europe change their current operation modes to different ones — operation in cycling mode with shut down or load reduction of generating units at night time. This research provides the investigation of changes in Riga CHP-2 plant operation modes, as the result of opening of Latvian price area in Nord Pool Spot (NPS) power exchange. Combined cycle gas turbine (CCGT) units of Riga CHP-2 plant were chosen as investigation objects. Negative and positive aspects of cycling operation of Riga CHP-2 plant were explored under conditions of open electricity market. Finally, some measures for modernisation and upgrade of Riga CHP-2 were recommended to improve efficiency of cycling operation and flexibility.

Real-time model for motor control coursework

Abstract: This paper considers the model of different types of electric drives which is designed as a project for Code Composer Studio for TMS320F28xx microcontrollers and is used in Motor Control course for coursework. The review of different solutions for motor control education course is given and the demands to the model are stated. The description of the model is given and the sample of the control system with experimental results is shown. The link to the project for Code Composer Studio and its description is given.

Uncertainty characterization of carrier-based demand response in smart multi-energy systems

Abstract: The concept of Carrier-Based Demand Response (CBDR) programs in Smart Multi-Energy Systems (MES) is proposed in this paper. It is discussed that by establishing the bi-directional relation between multi-energy demand and MES through the penetration of multi-carrier device technologies, the opportunity of demand-side participation in system operation can be activated. In this paper, the external dependency caused by multi-carrier devices is employed as a demand response. The CBDR is introduced as the flexibility of end-use to change the conversion pattern of input carriers into required demand. As the CBDR program is influenced by energy carrier prices, upstream network obligations and also the customer's behavior, its uncertainty is effectively modeled in this paper. The results compare the difference between the stochastic and deterministic approaches to the problem and show the improved accuracy through the stochastic modeling. The role of those customers that are not taking part in CBDR program is also investigated.

Zero-voltage switching implementation of a virtual infinite capacitor

Abstract: We define the virtual infinite capacitor (VIC) as a nonlinear capacitor that has the property that for an interval of the charge Q (the operating range), the voltage V remains constant. We propose a lossless zero-voltage switching realization for the VIC using a switched power converter and capacitors. This circuit is simple but it requires a complex control algorithm that we describe. There are two controllers needed to operate a VIC: the voltage controller acts fast to maintain the desired terminal voltage, while the charge controller acts more slowly and maintains the charge Q in the desired operating range by influencing the incoming current. The VIC is useful as a filter capacitor for various applications, for example power factor compensators (PFC), as we describe. In spite of using small capacitors, the VIC can replace a very large capacitor in applications that do not require substantial energy storage. We give simulation results for a PFC working in critical conduction mode with a VIC for output voltage filtering.

Long-term generation expansion planning under uncertainties and fluctuations of multi-type renewables

Abstract: This paper introduces a generation expansion planning model for a system integrated with multi-type renewables, specifically wind and PV, covering their joint uncertainty and fluctuation characteristics. Statistical Residual Load Duration Curve (S-RLDC) is proposed to deal with the uncertainty characteristic, in which the technique of convolution in separate time domain is adopted. Wavelet decomposition is applied to reveal the fluctuation amplitude of renewables, and further to determine the flexible capacity requirement for mitigating this fluctuation. As a case study, an actual district in the northwestern part of China is employed.

DC grid control through the pilot voltage droop concept: Mitigating consequences of time delays

Abstract: The control of the individual converters in a voltage-source-converter high-voltage dc (VSC-HVDC) based multi-terminal dc grid is central for the overall performance of the system A few different variants of power drooped against dc voltage control have been proposed in the literature for the purpose of distributing the power mismatch, following a disturbance, on several converters One such variant is the pilot voltage droop control concept which involves communication As is always the case when communication is involved, there is a risk of latencies and even communication failure This paper proposes a way to mitigate the consequences of latencies for the pilot voltage droop concept The approach may also have bearing on other control problems, involving communication, where the aim is to adjust the steady state solution based on remote measurements The proposed solution is established in a stepwise fashion starting from the basic control principle, and the performance is exemplified by time domain simulations with a four station dc grid using Digsilent's Powerfactory platform