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The real time co-simulation has been greatly developed all over the world. Through an interface that can enable the information exchange between two simulators, the co-simulation can synchronously simulate a large complex system. The objective of this paper is to present a real time co-simulation test bench using RT-Lab and CloudPSS-RT for analyzing the PV power generation system. The system structure, network partitioning methods, and the averaged modeling methods of the PV system are proposed in this paper. Through simulation results accuracy test and frequency-sweeping test, the accuracy and effectiveness of the co-simulation is verified.

Background: The penetration level of a wind farm with transient stability constraint and static security constraint has been a key problem in wind power applications. Objective: The study explores maximum penetration level problem of wind considering transient stability constraint and uncertainty of wind power out, based on credibility theory and corrected energy function method. Methods: According to the corrected energy function, the transient stability constraint of the power grid is transferred to the penetration level problem of a wind farm. Wind speed forecast error is handled as a fuzzy variable to express the uncertainty of wind farm output. Then this paper builds a fuzzy chance-constrained model to calculate wind farm penetration level. To avoid inefficient fuzzy simulation, the model is simplified to a mixed integer linear programming model. Results: The results validate the proposed model and investigate the influence of grid-connection node, wind turbine characteristic, fuzzy reliability index, and transient stability index on wind farm penetration level. Conclusion: The result shows that the model proposed in this study can consider the uncertainty of wind power out and establish a quantitative transient stability constraint to determine the wind farm penetration level with a certain fuzzy confidence level.

In order to further reveal the vertical random vibration characteristics of railway vehicles, using the system engineering method, taking the passenger, the train system, and the track system (ballast track) as a unified whole, a passenger-train-track vertical coupling dynamic model is established, and the vibration differential equations of the model are derived. In the model, passengers are regarded as a single-degree-of-freedom system attached to the bottom of the carriage, the train system is represented as a 10-degree-of-freedom multi-rigid body model, the track system is regarded as the infinite long Euler beam model with three layers of continuous elastic point support, and the Hertz nonlinear elastic contact theory is applied to the wheel and rail coupling relationship. Based on this, the time-domain numerical solution of the passenger-train-track vertical coupling dynamic model is given by using Newmark- β implicit integration algorithm, and the correctness of the model is verified by the real vehicle test. This study can provide some theoretical basis for the design of railway vehicles and provide fundamentals for the coordinated control and system optimization of railway vehicle ride comfort.

In order to analyze the influence of the rotor-bearing coupling vibration on the dynamic performance of electric vehicles driven by an in-wheel motor, taking a typical four-phase 8/6-pole switched reluctance motor driven electric vehicle without deceleration mechanism as an investigated object, a nonlinear dynamic model of an electric vehicle with the in-wheel motor driving system is established on the basis of considering the motor exciting force and the bearing nonlinear force. Through the numerical simulation, the influence of the rotor-bearing coupling vibration on the dynamic behavior of electric vehicle driven by the in-wheel motor is studied. Here, in this paper, the dynamic characteristics of an electric vehicle with and without motor exciting force and bearing nonlinear force are compared and analyzed. In addition, the influence of the suspension parameters on the dynamic performance of electric vehicle driven by the in-wheel motor is analyzed. According to the results, the influence of the rotor-bearing coupling vibration on the dynamic behavior of the electric vehicle is mainly embodied in the tire vibration acceleration and tire dynamic load. Moreover, the existence of the in-wheel motor driving system will deteriorate the evaluation index of the electric vehicle vibration performance. By choosing appropriate parameters of the vehicle suspension system, the ride comfort of the electric vehicle can be effectively improved.

Since most of the technologies for measuring distribution network’s ground parameters are mainly aimed at accuracy of the grounding capacitance, the grounding leakage resistance measurement is not accurate. In addition, the inaccuracy caused by the internal resistance of voltage transformer (VT) and the resonance elimination resistance is hard to avoid during the measurement, which results in a large error. Furthermore, traditional measurement methods cannot be applied to a variety of different system grounding methods, which are not conducive to practical applications. For this reason, this paper proposes a method to measure grounding leakage resistance of distribution network (DN) through zero-sequence voltage regulation. It selects the appropriate tap of the Y/ ∆ -connected grounding transformer external to the distribution network connected to ground to obtain a smaller zero-sequence voltage, and measures the zero-sequence current of the system at this time, and then substitutes the obtained voltage and current values into the calculation to get system grounding leakage resistance. The PSCAD/EMTDC simulation is run to prove the proposed method. The measurement results obtained have small errors and are suitable for different system wiring methods. It shows that the measurement method is of high accuracy, wide applicability, safety and economy to use.

Under the background of a large number of converters connected to the power grid, the converter’s weak overcurrent capability and poor anti-interference ability bring challenges and hidden dangers to the transient safe and stable operation of the power grid. It is urgent to carry out the transient characteristics analysis of the converter. Numerical simulation calculation is an important means to study transient characteristics. However, numerical simulation is time-consuming and poor in generality, which greatly limits the study of transient characteristics of systems with multiple converters. In this paper, the vertical control is the object, and the inverter reduced-order simplified model suitable for different transient stability problems is studied. First, a full-order model of the droop control inverter is established, and the singular perturbation method is used to complete the extraction of system characteristic roots and the analysis of participating factors. Then, according to the droop control of the inverter’s power angle, voltage, and frequency transient response process, accuracy and rapidity are selected as the goals, and a reduced-order simplified model suitable for different transient stability analysis is obtained. The transient characteristic analysis of the numerical simulation of the converter system provides a reduced order reference.

The current arc suppression method can theoretically compensate the ground current to zero, but it can only be estimated by the inherent parameters of the system because the fault point current cannot be measured directly. The compensation effect is not easy to observe directly, and the current arc suppression method cannot adapt to the change of distribution network. Voltage arc suppression is a emerging arc suppression method. There are various problems hinder the large-scale popularization and application of the new arc suppression technology in practical applications. This article discusses the differences between active and passive voltage arc suppression principles, technical characteristics, and technical difficulties that need to be resolved, and discusses the development direction of voltage suppression technology.

The traditional method of measuring grounding capacitance of distribution network is greatly affected by neutral grounding method, and the influence of harmonic elimination resistance and internal impedance of voltage transformer on measurement accuracy cannot be eliminated. Therefore, this paper proposes an accurate way to measure grounding capacitance of the distribution network which is not affected by the neutral point grounding method. It uses a special Y/ Δ-connected grounding transformer with taps connected to the distribution network to change the zero-sequence voltage of the distribution network by adjusting the grounding tap of the high-voltage side winding of the grounding transformer, and obtains the required zero-sequence through measurement voltage and zero sequence current to find the capacitance to ground of the system. The proposed measurement method is analyzed in PSCAD/EMTDC, which shows that the method has high measurement accuracy and is safe, simple and economical for the measurement of ground capacitance current.

In this paper, a new local quadratic wavelet neural network (LQWNN) method is proposed for short-term wind power generation prediction in power system. Due to the nonlinear structure of its local quadratic model (LQM), this method can effectively simulate the nonlinear behavior of wind power generation. In the time domain and frequency domain, wavelet function sets the effective region of LQMs in LQWNN, thus improving the learning efficiency and structural transparency of the overall model. The proposed LQWNN method employs a simple and effective particle swarm optimization (PSO) algorithm and optimizes its parameters. Through two real cases studies, namely the wind power forecast of the Irish power grid and the Jiuquan wind power plant in Gansu province, the performance of the proposed wind power forecasting method is evaluated and compared with other methods. The results show that the LQWNN method proposed in this paper is very effective in predicting wind power generation and has a good application prospect.

In this paper, a medium and long term output analysis model of multipoint access decentralized wind power based on Markov chain Monte Carlo method is proposed. The model considers the correlation among multi-point access decentralized wind farms and the multivariate first order Markov process is obtained by analogy with univariate higher order Markov process. Based on this, the state transition matrix of multi-point access decentralized wind power output is established, and the output distribution of four decentralized wind farms in Shantou is simulated according to the model. The statistical parameters such as mean, standard deviation, probability density function (PDF) and autocorrelation coefficient (ACF) of the generated wind power time series and historical series are compared. The results show that the statistical parameters of the simulated series are very close to those of the historical series. The model presented in this paper is very effective. Then this paper proposes a method for selecting typical daily output of decentralized wind power based on hierarchical clustering algorithm, and simulates the typical daily output of summer and winter of four decentralized wind farms in Shantou based on the model.

This work proposes an optimal wind farm layout framework to obtain the optimal placement of wind turbines in a wind farm. The optimization objective is to minimize the average cost per net electric power generated by a wind farm with a fixed number of turbines while the distance between turbines is no less than the allowed minimal distance in the far wake region. The wind farm micro-siting problem with Frandsen’s Gaussian wake model based on the conservation of momentum is formulated as a constrained optimization problem and solved by real-coded Genetic Algorithm. Simulation results demonstrate that the Frandsen’s Gaussain wake model is more consistent with real wakes and thus the optimization result is more accurate than the existing practices.

To improve comfort, a nonlinear suspension system is proposed on the basis of the nonlinear vibration isolation theory and the installation space of the cab suspension system for trucks. This system is suitable for all-floating cabs. For easy matching and design, the static and stability characteristics of the suspension system were analyzed, respectively, and the boundary condition for the stability of the system was given. Moreover, the cab simulation model was established, and the dynamic simulation was conducted. The stability analysis shows that the smaller the vibration excitation of the cab system, the higher its stability is. The dynamic simulation results show that the acceleration of the cab with the nonlinear suspension system is effectively suppressed; the dynamic deflection of the suspension is kept within a certain range, and the design space of the suspension stroke can be effectively utilized. Compared with the traditional linear suspension system, the nonlinear suspension system has better vibration isolation characteristics and can effectively improve ride comfort.

In order to analyse the mechanical characteristics of the traction motor hanging leaf spring of railway vehicles quickly and effectively, by establishing the vertical and the lateral force model of the hanging leaf spring, the mathematical model for analysing the stiffness characteristics and the stress characteristics of the hanging leaf spring were established based on analytical calculation, and the reliability of the mathematical model was verified by the loading-unloading test. The test results show that the analysis method for analysing the mechanical characteristics of the traction motor hanging leaf spring established is reliable. This research can provide a certain popularization and application value for the analysis and design of the railway vehicle traction motor hanging leaf spring.

This paper proposes an energy optimization management method of interaction between the smart energy hub (SEH) and users in the energy system. Internet of Things (IoT) and energy storage are also considered in the system. First, the models of the SEH and users are constructed. Then the profit models under the influence of energy storage are discussed. Next the Stackelberg game model is applied in this paper, where the SEH acts as the leader and the users are the followers. A double-layer algorithm is proposed to solve the problem. Finally, a case is studied to verify the correctness of the method. The results show that the method can be used for effective energy management in integrated energy system and IoT plays an important role in information exchange.

In order to reflect the vertical random vibration characteristics of railway vehicles more truly and effectively, this paper regards the human body as a single-degree-of-freedom system attached to the bottom of the carriage, and establishes a vertical dynamic model of railway vehicles by considering the influence of the coupling vibration effect between the passenger and the car body. The correctness of the model is verified by the real vehicle test. Then, the influence of the passengers on the vertical vibration characteristics of railway vehicles is analyzed, and the influence of the railway vehicle vibration on the vertical vibration characteristics of passengers is discussed in this paper. The research made in this paper can provide an effective model reference for the analysis of the vertical random vibration characteristics of railway vehicles and passengers, and for the optimization design of the suspension system parameters.

To define the application fields of the traditional cab system model and the seat–cab coupled model, this paper mainly aims to investigate the differences of the vibration characteristics of the two models. First, the two models and their motion equations were introduced. Then, based on the mechanical parameters of the seat and cab system for a truck, the transmissibility characteristics of the two models were analyzed. The results show that the traditional model can relatively accurately predict the pitch and roll vibration characteristics of the real seat–cab system. However, it overvalues the vertical vibration transmitted from the front suspensions of the cab. Third, the typical excitation conditions and the measuring points were selected. Finally, under the typical excitation conditions, the dynamic responses of the measuring points were calculated. The results show that under the vertical excitation condition, the dynamic responses of the two models have obvious differences. Under the roll excitation condition and the pitch excitation condition, the roll responses and the pitch responses of the cab between the two models show almost no obvious difference. Under the random excitation condition, the vertical acceleration responses have relatively larger deviations between the two models, however, the angular acceleration responses are almost the same. For the preliminary design of the cab system, the traditional cab system model can be used. However, for the accurate design and the optimization of the seat–cab system, the seat–cab coupled model is recommended.

To make a rapid comfort assessment and a reasonable dynamic parameters choice of wheelchair robots, this paper proposes a dynamic comfort coefficient [Formula: see text] and analytically optimizes the cushion damping. Firstly, a traveling vibration model of the occupant-wheelchair system for wheelchair robots running on random roads was created. Secondly, the analytic formula of the occupant RMS (root mean square) acceleration was deduced. Moreover, the dynamic coefficient [Formula: see text] was proposed and its influence laws were revealed. Finally, the cushion system optimal damping ratio was calculated based on [Formula: see text]. The results show that the [Formula: see text] value is only determined by the parameters of the occupant-wheelchair system. The smaller the [Formula: see text] value is, the better the dynamic comfort is for wheelchair robots running on random roads. By minimizing [Formula: see text], the occupant-wheelchair system can achieve a statistically optimal dynamic comfort effect.

Based on the governing differential equation for deformation of throttle slice, while satisfying required boundary conditions, an analytical formula for computing the deformation of throttle slice was presented through equivalency transformation, which is a concise, accurate and practical method for throttle slice design. The deformation at any radius was computed, compared with ANSYS FEA software by the simulation analysis. The result shows that the new method is an accurate analytical method for computing the deformation of throttle slice at any radius, suitable to use in the design of valves parameters.