Location and Capacity Determination Method of Electric Vehicle Charging Station Based on Simulated Annealing Immune Particle Swarm Optimization

As the number of electric vehicles(EVs)continues to grow and the demand for charging infrastructure is also increasing,how to improve the charging infrastructure has become a bottleneck restricting the development of EVs.In other words,reasonably planning the location and capacity of charging stations is important for development of the EV industry and the safe and stable operation of the power system.Considering the construction and maintenance of the charging station,the distribution network loss of the charging station,and the economic loss on the user side of the EV,this paper takes the node and capacity of charging station planning as control variables and the minimum cost of system comprehensive planning as objective function,and thus proposes a location and capacity planning model for the EV charging station.Based on the problems of low efficiency and insufficient global optimization ability of the current algorithm,the simulated annealing immune particle swarm optimization algorithm(SA-IPSO)is adopted in this paper.The simulated annealing algorithm is used in the global update of the particle swarm optimization(PSO),and the immune mechanism is introduced to participate in the iterative update of the particles,so as to improve the speed and efficiency of PSO.Voronoi diagram is used to divide service area of the charging station,and a joint solution process of Voronoi diagram and SA-IPSO is proposed.By example analysis,the results show that the optimal solution corresponding to the optimisation method proposed in this paper has a low overall cost,while the average charging waiting time is only 1.8 min and the charging pile utilisation rate is 75.5%.The simulation comparison verifies that the improved algorithm improves the operational efficiency by 18.1%and basically does not fall into local convergence.

Operational risk assessment of third-party payment platforms:a case study of China

Operational risk events have severely impacted the development of third-party payment(TPP)platforms,and have even led to a discussion on the operational risk capital charge settlement by relevant international regulators.However,prior studies have mostly focused on qualitative mechanism analysis,and have rarely examined quantitative risk assessment based on actual operational risk events.Therefore,this study attempts to assess the operational risk on TPP platforms in China by constructing a systematic framework incorporating database construction and risk modeling.First,the operational risk database that covers 202 events between Q1,2014,and Q2,2020 is constructed.Then,specific causes are clarified,and the characteristics are analyzed from both the trend and loss severity perspectives.Finally,the piecewise-defined severity distribution based-Loss Distribution Approach(PSD-LDA)with double truncation is utilized to assess the operational risk.Two main conclusions are drawn from the empirical analysis.First,legal risk and external fraud risk are the two main causes of operational risk.Second,the yearly Value at Risk and Expected Shortfall are 724.46 million yuan and 1081.98 million yuan under the 99.9%significance level,respectively.Our results are beneficial for both TPP platform operators and regulators in managing and controlling operational risk.

Structural jump-diffusion model for pricing collateralized debt obligations tranches

This paper considers the pricing problem of collateralized debt obligations tranches under a structural jump-diffusion model, where the asset value of each reference entity is generated by a geometric Brownian motion and jump with an asymmetric double exponential distribution. Conditioned on the common factor of individual entity, this paper gets the conditional distribution, and further obtains the loss distribution of the whole reference portfolio. Based on the semi-analytic approach, the fair spreads of collateralized debt obligations tranches, i.e., the prices of collateralized debt obligations tranches, are derived.

Improved Efficiency Test Method for the Motor Controller with SiC MOSFETs

The traditional measurement method was inaccurate to evaluate the motor controller efficiency,which the measurement efficiency value could be more than 100%in practical testing experiments.To deal with this issue,an improved electrical measurement method for the motor controller efficiency is proposed in this paper,which is established by analyzing the power loss distribution and phase currents of the motor controller.It is demonstrated that the SiC MOSFET chips are the main power loss devices in the motor controller,accounting for more than 93.1%of the total power loss.The accuracy of the proposed method is compared with the traditional method in simulation.It shows that the test error of the efficiency obtained by the traditional method fluctuates on a large scale,which varied from 0.094%to 1.911%.Compared with the traditional method,the test error of the proposed method appears to be less than 0.083%,which provides significant guidance for the motor controller efficiency test and design.

An Improved Submodule Unified Pulse Modulation Scheme for a Hybrid Modular Multilevel Converter

This paper presents an improved submodule unified pulse width modulation(SUPWM)scheme for a hybrid modular multilevel converter(MMC)composed of half-bridge submodules(HBSMs)and full-bridge submodules(FBSMs).The proposed SUPWM scheme can achieve an output voltage of(2N+1)(where N is the number of submodules in each arm)levels,which is the same as that of the carrier-phase-shifted PWM(CPSPWM)scheme.Meanwhile,the proposed SUPWM scheme can alleviate the uneven loss distributions between the left leg and right leg in FBSMs of the hybrid MMC.Moreover,the capacitor voltages of the sub-modules can be well balanced without complicated closed-loop voltage balancing controllers.The validity of the proposed SUPWM scheme is verified by both the simulated and experimental results.

Power system reconfiguration and loss minimization for a distribution systems using ＂Catfish PSO＂ algorithm

One of the very important ways to save electrical energy in the distribution system is network reconfiguration for loss reduction. Distribution networks are built as interconnected mesh networks; however, they are arranged to be radial in operation. The distribution feeder reconfiguration is to find a radial operating structure that optimizes network performance while satisfying operating constraints. The change in network configuration is performed by opening sectionalizing （normally closed） and closing tie （normally opened） switches of the network. These switches are changed in such a way that the radial structure of networks is maintained, all of the loads are energized, power loss is reduced, power quality is enhanced, and system security is increased. Distribution feeder reconfiguration is a complex nonlinear combinator- ial problem since the status of the switches is non- differentiable. This paper proposes a new evolutionary algorithm （EA） for solving the distribution feeder reconfiguration （DFR） problem for a 33-bus and a 16- bus sample network, which effectively ensures the loss minimization.

Establishment of a Static Model Based on Measured Heat Loss for COREX Process

The heat loss and its,distribution are of great importance for the calculation and simulation of COREX process. Based on Baosteel COREX process, a method was applied to measure the heat loss of the furnace shell, the accessory equipments and the cooling water system. Then, a static model was established based on the measured heat loss of COREX process. The results showed that the main heat loss of furnace shells took place at the dome of the COREX melter-gasifier and the reducing gas entrance position of the shaft furnace while the main heat loss caused by cooling water occurred at the tap hole area. And the heat loss caused by cooling water accounts for about 85% of the total heat loss in COREX process. The measured total heat loss for producing every 1 t hot metal was 542. 164 MJ, which accounted for about 92 % of the theoretical total heat loss.

Field study of a soft X-ray aerosol neutralizer combined with electrostatic classifiers for nanoparticle size distribution measurements

Most conventional aerosol neutralizers are based on radioactive sources, which are controlled by strict regulations restricting their handling, transport, and storage. The TSI 3087 soft X-ray （SXR） neutralizer circumvents these legal restrictions. The aim of the present work is to compare the performance of a standalone SXR aerosol neutralizer with that of conventional radioactive aerosol neutralizers based on 85Kr （TSI 3077） and 241Am （Grimm 5522） by performing field tests in a real environmental scenario. The results obtained when the SXR neutralizer was connected to a mobility particle sizer spectrometer （MPS）, different from the device suggested by the manufacturer, were comparable with those obtained with the use of radioactive aerosol neutralizers. In changing the neutralizer, the particle number concentrations, measured with the MPS connected to the SXR neutralizer, almost remained within the 10% uncertainty bounds for the particle size interval 10-300 nm, when diffusion losses inside the SXR tube were considered. Based on our comparisons, the SXR neutralizer can be regarded as a standalone instrument that could solve the problems associated with legal restrictions on radioactive neutralizers and fulfil the need for a portable instrument for different field test purposes.

Effect of optical losses on the transmission performance of a radio-over-fiber distributed antenna system

The effects of optical losses oil a directly-modulated radio-over-fiber （RoF） system used for distributed antenna networks are determined. The results show that with a properly designed bidirectional amplifier, the RoF link can tolerate over 20 and 16 dB of optical losses for down- and up-links, respectively. Simulation results are also consistent with the experimental data. These findings can contribute to tile design of RoF distributed antenna systems with different topologies.

Evaluation of Feasible Interlinking Converters in a Bipolar Hybrid Microgrid

A bipolar hybrid microgrid is a new topology which benefits from the advantages of both alternating current(AC)and direct current(DC)microgrids.Interlinking AC/DC converter is the key of this topology which has the following characteristics:being able to provide two equal pole voltages in DC side;complying with the standards of current quality at AC side;being able to control active and reactive power independently in AC side,and transmitting bidirectional power.In this paper,two categories of power converters including single-stage and two-stage converters are proposed for this topology.A new cost-effective control strategy is added to the control of general grid-connected converter for each interlinking converter,and the control of autonomous DC-link pole voltage for both candidates is achieved.Detailed simulations based on the designed control strategies are conducted to validate the function of control strategies under the operation conditions of different DC sides.The performances of two selected interlinking converters with balanced and unbalanced DC loads are analyzed.Suggested power quality of microgrid and total harmonic distortion(THD)analysis are demonstrated in grid-tied and islanded modes.Eventually,semiconductor power loss simulations based on a closed-loop thermal network simulation are conducted.Thereby,the mutual effects of power loss and initial junction temperature are investigated.