Showing papers presented at "International Conference on Power Electronics Systems and Applications in 2022"

Power System Inertia Estimation Based on 1-Dimensional Deep Convolution Neural Network

Abstract: With the increasing penetration of renewable generation, the inertia of modern power system gradually decreases, resulting in relatively larger frequency deviations under perturbation. Existing system inertia estimation methods exhibit poor adaptability and insufficient accuracy for industrial applications. In this paper, a system inertia estimation algorithm based on a one-dimensional deep convolution neural network (ID-DCNN) is proposed. First, a multi-layer 1-dimensional convolution model is designed to extract abundant temporal features from system frequency waveforms. Subsequently, the hyperparameters and network structure of the model are adjusted to reduce the estimation error and enhance the generalization ability of the deep network model. The New England 10-machine 39-node system is utilized to validate the effectiveness of the proposed method. Numerical results show that the proposed method can accurately evaluate the system inertia after offline training.

The Effects of Charge and Discharge Behaviors Based on Lithium-ion Battery Model

Abstract: More attention recently has been paid to electric vehicles (EVs) due to the characteristics of low carbon emission, quiet noise, and environmental-friendly. The battery is one of the core components for EVs which provides energy to drive the entire force system. State-of-Charge (SOC) and State-of-Health (SOH) of the battery describe how the battery works and reflect the battery model characteristic between the charge and discharge conditions. In this paper, based on the NASA datasets and the existed battery model, the effects of SOC and SOH for battery modeling are analyzed and an improved battery modeling is provided. The effectiveness of the proposed battery modeling is verified through MATLAB/SIMULINK software.

Research on Misalignment Tolerance Optimization Method for EV Wireless Power Transfer System

Abstract: In electric vehicle wireless power transfer (EVWPT) systems, misalignment tolerance has always been one of the concerns. This paper proposes an optimization method of EVWPT system misalignment tolerance through coupling mechanism design and circuit topology analysis. Using the mutual inductance complementary characteristics of the compensation coil and the receiving coil, and using the output series topology, the system has good misalignment tolerance performance and constant voltage (CV) output characteristics. Theoretical analysis and simulation results verify the effectiveness of the proposed method, and the system can achieve good load-independent CV output within the range of 50% misalignment.

An Interleaved-Type Inverter Based on Switched-Capacitor and Filter Inductor

Abstract: In this paper, an interleaved-type inverter topology based on switched-capacitor (SC) and filter inductor is proposed. At first, the topology consists of two four-level switched-capacitor inverter modules and a coupled inductor. The two inverter modules are connected by a coupled inductor in parallel. The role of the coupled inductor is to increase the number of output levels. On this basis, the topology is optimized and the coupled inductor is replaced by two filter inductors. The optimized topology reduces the output THD and realizes the self-balance of capacitor voltage. The interleaved PD-PWM strategy is adopted in this parallel structure to reduce the ripple of output. The simulation verifies the feasibility of the topology.

Transient Analysis and Control Solutions for DFIG-based Wind Turbine Generators to Improve FRT Performance under Asymmetrical Faults

Abstract: Modern grid codes require wind turbine generators (WTGs) to ride through asymmetrical faults and inject positive- and negative-sequence reactive currents within a defined response time. In doubly fed induction generator (DFIG) based WTGs, a coupling loop is introduced under asymmetrical fault by the grid impedance among phase-locked loop (PLL), and inner and outer control loops. As a result, DFIG-based WTGs may react much slower than expected depending on the design of control parameters, due to grid impedance and asymmetrical voltage dip. The impact of this coupling loop on the phase angle transient is analyzed in this paper. In order to speed up the transient response, a magnitude normalization element is employed in the PLL to eliminate the impact of voltage magnitude dip, and the PLL control parameters are redesigned to increase the damping ratio. The proposed solutions are validated by a detailed EMT-type simulation in the EPRI benchmark system. The comparisons show that the FRT performance of the DFIG-based WTGs is improved by decreasing the overshoot and settling/rising time of the phase angle transient.

Smart Substation Performance Evaluation Method Based on Network Traffic

Abstract: Smart substation is an important part in the cyber-physical power system, whose information flow in the secondary system possesses the key function of reflecting and regulating the energy flow in the primary system. In order to achieve a further refined characterization of network traffic, information source models of devices at the bay level and process level are constructed. On this basis, a set of mathematical models about network injection traffic considering different substation operating conditions is formed by the source models of all the devices connected to the process level network. And a substation performance evaluation method based on process level network traffic is proposed, which enables the determination of the operating conditions experienced by a substation in a certain time period based on the injection traffic, providing a new method for real-time monitoring of the operating performance of smart substations.

Special Estimation Analysis for the Position of Switched Reluctance Machine using Sinusoidal Inductance Model

Abstract: Fourier modelings of the inductance of switched reluctance machines have been extensively investigated extensively in the past, but the skills are restricted to the construction of the inductance profile model at a known motor position. This paper gives a presentation of a novel sensorless position estimation method based on online sinusoidal modeling of relative inductance for switched reluctance motors at startup. The background of this method is based on sinusoidal fitting and only very few data points are needed. It is numerically efficient and can provide accurate position information for each phase. There is no special requirement on the inductance profile of the machine, and the magnetic characteristics of the machine are not required. The method is simple and easy to implement. Experimental results have confirmed its validity.

A comparison of Series- and Parallel-Hybrid Compenstion Topologies for EV Wireless Charging Systems

Abstract: Wireless Power Transfer (WPT) is capable of transferring power in a non-contact manner and has excellent application scenarios for electric vehicle (EV) charging. This paper presents a comparison between the series and parallel hybrid compensation topologies, and with the normal series and parallel compensation networks as reference. Those two hybrid topologies are dual-circuits where the negative feedback in the main power transfer channel is built using the complementarity characteristics between the normal series and parallel compensation network. As the misalignment of the WPT pads, the dual-circuit construction counteracts the effects of parameter changes and eliminates the need for sensors and feedback controllers. Meanwhile, those dual-circuits have different charging profiles that may suitable for different EV wireless charging scenarios. Therefore, 400 mm of air gap and 160 mm of lateral and longitudinal pad misalignment were taken into account in the 3.3 kW system and compared side by side. The system efficiency, ZVS operating region are all presented in order to clarify the key advantages, as well as, the limitations of the hybrid compensation topologies with considering the practical end-user experience.

Review and New Developments of Adaptive Tunning Technologies for Wireless Power Transfer

Abstract: High-power-factor resonant system is of key importance to improve the transmission efficiency and power of inductive-coupled wireless power transfer system. However, quality factor of resonant circuit is vulnerable to system parameter changes, which causes system detuning. The adaptive-tunning technology solve the detuning problem by rematching the resonance parameters so that the system can always work in the resonant state, ensuring the efficient and high-power transmission of the system. Because of the unique features of wireless power transfer system including isolated transmitter and receiver side, delay of communication, and wide-range parameter variation, there is additional challenges of adaptive-tunning technology compared to its application in traditional converters. This paper firstly introduces the resonance characteristic of wireless power transfer system, then summaries the existing adaptive tunning technologies, including frequency tracking and dynamic compensation. Finally, a summary regarding adaptive tunning of WPT systems are discussed.

Power Electronics in Modern Power Systems

Abstract: The development of modern power system is briefed, in particularly, the applications of renewable energy and power electronic technologies. The new features and challenges of the changing power systems are described, and some recent research results are introduced.

A Novel Design of Wireless Charging Glove

Abstract: As a novel sort of electric energy transmission technique, wireless power transfer (WPT) efficiently eliminates several of the drawbacks of cable charging in power supply scenarios. As a consequence, a new wireless charging glove is developed in this paper to examine the feasibility and performance of wireless charging by using a flexible and bending circuit architecture. In terms of interoperability, the glove will be able to link to other devices in a close manner. In addition, power can be transmitted in both directions within the power transmission glove. The battery load can provide electricity to other devices or receive power from an external source. The rationale for the existence of this strategy as well as its characteristics is further discussed. The statistics and performance of both gloves will be discussed in the reports. More data will be displayed, and the observations will be commented on and explained.

Distributed Event-Triggering-Based Convex Optimization Control for Power Loss Mitigation in DC Microgrids

Abstract: In most research literatures, only wire loss is considered in the traditional optimization method for DC microgrid efficient operation. In this work, a distributed three-layer control scheme, which comprises a top-layer distributed gradient descent method (DGDM), a middle-layer distributed event-triggering control, and a bottom-layer local control, is designed to minimize the distribution loss for DC electric network. The proposed control is inherited from traditional distributed control by using node-to-node communication among the neighboring DERs, which gains the merits of higher robustness and scalability than the conventional centralized control. The loss in DC microgrids includes both loss by wire lines and loss by converters, as proposed in this work. By comparing with the traditional line loss optimization strategy, more loss in DC electric network can be reduced by the proposed strategy. Besides, the communication burden is significantly reduced by using event-triggering-based distributed secondary control. Various cases' results are provided to verify the effectiveness of the event-triggering-based DGDM.

A 3-D Rotating Magnetic Field Modulation Method for Omnidirectional Wireless Power Transfer Systems

Abstract: In this paper, a three-dimensional (3-D) rotating magnetic field modulation method based on phase-shift control is proposed to realize omnidirectional wireless power transfer (WPT). The proposed method can realize 3-D omnidirectional WPT when only a planar single-coil receiver is used. In addition, the proposed method does not need to detect the orientation of the receiving coil, complex control, and communication links. Firstly, the magnetic coupler and circuit structure of the system are given, and then the working principle of a generating three-dimensional (3-D) rotating magnetic field is introduced. On this basis, the modulation method of the 3-D rotating magnetic field is given. Finally, the effectiveness of the proposed method to achieve 3-D omnidirectional WPT is verified by simulation. The simulation results show that the pickup power is maintained at 62-77W when the receiver rotates arbitrarily.

SOC Estimation Method of Lithium-ion Batteries Based on Relaxation Effect and GRU-RNN

Abstract: State of charge (SOC) of lithium-ion battery is one of the key parameters for battery management system (BMS). This paper proposes a SOC estimation method of lithium-ion batteries based on relaxation effect and gated recurrent unit recurrent neural network (GRU-RNN). Firstly, the SOC estimating model based on relaxation effect is proposed using GRU-RNN. Then, a periodic discharge experiment is designed according to the characteristics of relaxation effect, which is used to collect voltage relaxation dataset. Finally, the proposed model is trained using the voltage relaxation dataset, and the SOC estimation results of proposed model under different discharge currents are verified.

Design and Co-Simulation of High-Speed Permanent Magnet Brushless DC Motor

Abstract: In recent years, the application of high-speed motor in various aspects has been widely concerned. High speed permanent magnet brushless DC motor has the characteristics of high power density and high efficiency. However, with the increase of speed, the iron consumption of the motor increases significantly compared with the conventional motor, which affects the efficient and safe operation of the motor. In this paper, a high-speed permanent magnet brushless DC motor with inner rotor is designed, which adopts low loss amorphous alloy material 1k101. Through the finite element design analysis and joint simulation of the motor, the rationality of the designed motor is verified, which is of great significance to improve the operation performance of high-speed permanent magnet brushless DC motor.

Unveiling the Benefits of Condensed Water Reclaimed for Evaporative Cooling Tower in Part I: Water Conservation

Abstract: The water conservation bodies have recited the use of grey-water to alleviate water consumptions. The intrinsic mineral-free condensed water is not only an ideal dilution but also a by-product of air-conditioning, which may be reclaimed at no extra cost and energy, is conducive to the efficacy of chemical reagents for descaling. The major water evaporation losses are replenished with fresh water that increases the mineral concentrations with time and aggravates water scale formations. The total dissolved solid (TDS) are effectively lowered by bleed-off that is determined by the cycles of concentration (CoC). The higher CoC is, the less bleed-off will be. The electrical conductivity (EC) controller controlled the level of TDS with auto bleed-off valve which is complementary to chemical dosing system that retards the nucleation and crystal growth in the mineral laden water. Considering that the maximum industrial standard 2,500ppm, fresh make-up water 130ppm, and condensed water 69ppm, CoC 19.2 was set. Consequently, 44 % make-up and 80% bleed-off water were saved that would resulted in the greenhouse gas (GHG) emissions reduction of around 7,500 kg CO2e/yr

Advanced Wireless Power Conversion Technologies Topology, Modulation, and Control

Abstract: The consumer electronics industry is experiencing a significant paradigm shift from wired charging to wireless charging. This scenario will be further enhanced as more applications are adopting wireless charging. As a result, it is required that wireless power conversion technologies should be able to cope with the new challenges raised by these emerging applications effectively. This presentation will start with an overview of key dimensions of existing wireless power transfer systems (i.e., topologies, modulation, and control) along with the advantages and trade-offs of various solutions. Furthermore, some new challenges to the stability of existing wireless power transfer systems are discussed and analyzed. In addition, the implementation, dynamic modelling, load estimation and control of multi-coil mid-range wireless power transmission systems are introduced. Finally, conclusions are drawn, and prospects are provided for future research and development of wireless power conversion technologies.

A Cost-effective Magnetic Coupler Design with Hexagonal Coils for Electric Vehicle Wireless Charging Systems

Abstract: Recent engineering investigations tend to focus on the cost-effectiveness of wireless power transfer (WPT) in electric vehicles (EVs). One promising method is to save raw material usage from the magnetic coupler part. LITZ wire is widely used in EV wireless charging systems, which is more expensive than conventional wires. It is feasible to save LITZ wire usage with a delicate magnetic coupler design. This article presents a configurable magnetic coupler to realize constant current (CC) and constant voltage (CV) for wirelessly charging battery-oriented applications. Such a magnetic coupler utilizes hexagonal coils to save raw material usage. Most importantly, the main magnetic coupling between the transmitting and receiving coil can be enhanced. And the undesirable magnetic coupling between the source and receiving coil can be reduced. Simulation validation of coils is conducted through finite element analysis (FEA) with the help of ANSYS Maxwell. Circuit analysis is conducted to verify the CC and CV characteristics theoretically.

Evaluation Method of Business Matching Degree in Autonomous and Controllable New Generation Smart Substation

Abstract: Autonomous and controllable new generation substation is a new form of smart substation development in the future, so as to realize more safe and reliable, advanced and applicable, and intensive and efficient. In order to evaluate the matching degree of the networking scheme and the business flow in substation secondary system, this paper draws on the graph theory and matrix analysis to depict the substation network architecture by information interaction path. Combined with different business characteristics, a business flow importance indices evaluation system is constructed based on the analytic hierarchy process and entropy weight method. The case analysis shows that the business flow importance calculation can effectively optimize the substation networking scheme design, which can ensure that the nodes with high importance and the key information interaction paths are covered, and then the feasibility and rationality of the matching degree evaluation method are verified.

Distributed Generation Using Buck Converters Based on Consensus Control in DC Microgrid Integrations

Abstract: Traditional centralized control relies heavily on the communication network, and therefore, a single subsystem communication failure could cause the entire microgrid down. Consensus control eliminates the need for the central controller, which is more cost-effective. In addition, because of distributed communication, the microgrid can continue to function correctly even if there are brief communication disruptions. The methodology proposed in this paper is based on consensus control and deployed with multi-agent systems. The entire system could supply the same stable output current according to the different levels of generation. To establish consensus control of the whole microgrid, information exchange in neighbor mechanisms has been designed separately for local control. In addition, the stability and robustness of the entire system will be assessed with load variations at a specific time. Each agent will adjust its duty cycle in real-time based on the information of neighbors, leading to a system-wide consensus. The proposed strategy is emerging as an attractive technology option to promote the use of DG and manage demand loads.

A Matrix Converter Based Wireless Power Transfer System for High-Speed Train

Abstract: A matrix converter (MC) based wireless power transfer (WPT) system for high-speed train is proposed in this paper. The pantographs in conventional traction system are replaced with the transmitting and receiving coils in WPT system. Therefore, the reliability can be increased and the maintenance cost for pantographs will be reduced. Moreover, the DC-link capacitors which are required in conventional two-stage WPT system is eliminated with MC. Therefore, the system reliability and power density can be increased wilt the absence of physically large and heavy aluminum electrolytic capacitors. Finally, a laboratory prototype is designed and experiments are carried out to verify the effectiveness of the proposed MC based WPT system.

Tapped Inductor Works on Switched Mode Power Converter for Electric Vehicle Power Conversion System

Abstract: Switched-capacitor technique has a good application for voltage source circuits. On the other hand, the switched-inductor approach in current source circuits can also produce different possibilities for the output circuit. When the tapped inductor is added to the circuit, it will affect the load side again, and the way to access the circuit is different; it is conversion has an extensive range. This paper introduces the method, in the case where the components remain unchanged and the circuit connection mode changed, to make the output current change during the use of the relevant power circuit. How to calculate and design the power supply circuit you need according to your needs during the use of the appropriate power supply circuit. This circuit can be applied to photovoltaic cell output conversion, current mode motor control, and some energy distribution. It can also be used in electric vehicle (EV) power conversion. The current mode control is especially used for current mode charging of EV charger.

A Self-Tuning Method for Performance Enhancement of Wireless Power Transfer under Capacitance Drift

Abstract: The performance of wireless power transfer (WPT) system is dependent on resonance between coil inductor and compensation capacitor. However, temperature variation or aging would lead to capacitance drift of the compensation capacitor. This factor causes detuning of the WPT system which affects power transfer performance. In order to solve the problem, a self-tuning method for anti-capacitance drift is proposed in this work. Firstly, the influence of capacitance drift on power transfer is analyzed. Then, a novel WPT system is designed by introducing a nonlinear magnetic ring. The characteristic of the magnetic ring is presented and the proposed WPT system is mathematically described. Finally, simulation work is carried out to verify the effectiveness of the proposed method.

Research on Simultaneous Wireless Power and Data Transfer System based on ASK Modulation

Abstract: In order to solve the information interaction problem of electric vehicles during wireless charging, this paper proposes a method for simultaneous wireless power and data transfer (SWPDT) system based on ASK modulation. The method uses frequency division multiplexing technology to achieve simultaneous transfer of power and data, power and data transfer share the same coupling mechanism, and the power transfer channel is separated from the data transfer channel through the LC wave blocking network, which greatly enhances the flexibility of the system. The problem of self-transmitting and self-receiving data is solved by using single-blade double-throw switch to realize the conversion of data transfer direction. In this paper, the SWPDT topology is given, the power and data transfer model is analyzed and established, the simulation model is built by MATLAB/Simulink simulation platform, simulation results show that the system can realize the Simultaneous transfer of power and data, and finally the feasibility of the method is verified by experiment.

An S-S Compensated WPT System for Electric Vehicle Battery Charging with Capacitor Matrix

Abstract: In the static wireless power transfer (WPT) system for electric vehicle (EV), constant output current (CC) and constant output voltage (CV) mode needs to be applied for better battery charging quality. In this paper, a series-series (S-S) compensated wireless charging system with capacitor matrix is proposed. By detecting the primary winding current and secondary output voltage, the mutual inductance between the primary coil and secondary coil can be calculated. With wireless communication between the primary side and the secondary side, the compensated capacitor matrices on both sides are controlled base on the mutual inductance and battery charging voltage. The CC/CV mode for battery charging can be achieved by changing the value of the capacitor matrices. Based on the simulating and experimental results, constant output current and voltage can be generated by switching different compensated capacitors, an easy control of EV battery CC/CV charging is thus realized.

Reliability and Aging Analysis for Power cables

Abstract: The paper proposes a method for life estimation of power cable under different conditions. Due to the complex application environment, the power cable is easy to have aging issues and lead to the failure of the entire system. Especially when it is used in a high temperature and high humidity environment, it will accelerate the aging of the cable. When the electrical parameters of the system transient changes dramatically, the operating temperature on the cable will rise sharply, thus affecting the reliability and service life of the cable. Therefore, it is necessary to carry out an aging analysis to predict the service life of the cable. The method is based on Arrhenius model, which predicts the life of the cable by detecting the leakage current and discharge characteristics at different temperatures and humidity.

Research on location planning of electric heating equipment connected to distribution power system based on load distribution method

Abstract: With the gradual deepening of multi energy coupling, the electric-heat coupling energy system has become the focus of academic attention. The main development trend is to use electricity to replace fossil fuels for heating. In this paper, aiming at the electric thermal coupling energy system, the power grid expansion and planning problems caused by the connection of electric heating equipment are studied. This paper introduces the impact of electric heating equipment connected to the power supply and distribution system. Taking the electric boiler connected to the power distribution system as an example, a distribution network planning model is established to optimize the load distribution of the electric boiler. The particle swarm optimization algorithm is used to solve the problem, and a distribution system planning scheme considering the access of electric boiler equipment is obtained. Through the planning of 16 node distribution network in a park, the planning results that make the expansion line and the investment cost of electric boiler reach the optimal are finally obtained, which proves the economy and feasibility of the proposed planning scheme.

Battery Charging Circuit of Wireless Power Transmission Receiver Side for Electric Bicycle

Abstract: In this paper, we design a low component-intensive charging circuit for a wireless power transmission system, which is applied in an electric bicycle. The system is composed of a rectifier, a driving circuit, a primary power topology, and a sampling feedback topology. The circuit can be used as the secondary side circuit of a wireless power transmission system for an electric bicycle battery as the receiving end of electromagnetic energy transmission. The circuit topology has low electronic component density, which is used to promote the use of electric bicycles on a larger scale. In order to verify the propose circuit, simulation results and experimental results are presented, which well validate its feasibility.

Electric Vehicle and Electrical Engineering Teaching Experience During Pandemic Disease

Abstract: During the three years of Pandemic Disease, the world of academic teaching has had a substantial change. The usual in-person or face-to-face teaching has been transformed into online teaching. For electrical engineering, the instruction usually includes heavyweight experiments or practical tests; therefore, online teaching faces challenges. A recent electric vehicle course has been proposed in the Master level and the challenge of the course is reported in this paper. The experience that has been encountered is discussed and the proposed method of teaching is described in the paper. Useful experience and learning outcomes are listed. Data are collected before and after the Covid-19 teaching. It is found that online education did not deteriorate the learning outcome.