Overload Constraints Research Articles

A novel constrained skew-Gaussian filter and its application to maneuverable reentry vehicle tracking

The state of the system generally satisfies specific constraints imposed by material properties or physical laws, so the application of these constraints can improve the accuracy of state estimation. In this paper, a novel recursive filter referred as constrained high-degree cubature skew-Gaussian filter (CHCSGF) is proposed, which achieves soft-constrained state estimation by compressing the probability density of unconstrained states with constraint information. First, the probability density of the state under inequality soft constraints is modeled as a skew-Gaussian (SG) distribution, rather than truncated or single Gaussian distributions. Then, a recursive constrained SG filter is developed to handle inequality soft constraints in linear systems. Addressing nonlinear challenges, a 5th-degree spherical-radial cubature approximation method is presented to numerically calculate SG-weighted integrals for the nonlinear transformation of SG distribution. Finally, the CHCSGF algorithm is proposed using this method to tackle nonlinear filtering problems. The CHCSGF is applied to reentry trajectory tracking to improve estimation accuracy by dealing with heat flow, dynamic pressure and overload constraints during reentry flight. Simulation results demonstrate that the CHCSGF achieves higher estimation accuracy than unconstrained methods under nonlinear inequality soft constraints, and is robust to the constraints with a prior error. Compared to particle filter and moving horizon estimation, the computational complexity of CHCSGF is significantly reduced.

Distributed Charging Strategy of PEVs in SCS with Feeder Constraints Based on Generalized Nash Equilibria

In this article, a distributed charging strategy problem for plug-in electric vehicles (PEVs) with feeder constraints based on generalized Nash equilibria (GNE) in a novel smart charging station (SCS) is investigated. The purpose is to coordinate the charging strategies of all PEVs in SCS to minimize the energy cost of SCS. Therefore, we build a non-cooperative game framework and propose a new price-driven charging control game by considering the overload constraint of the assigned feeder, where each PEV minimizes the fees it pays to satisfy its optimal charging strategy. On this basis, the existence of GNE is given. Furthermore, we employ a distributed algorithm based on forward–backward operator splitting methods to find the GNE. The effectiveness of the employed algorithm is verified by the final simulation results.

Research on Power Service Route Planning Scheme Based on SDN Architecture and Reinforcement Learning Algorithm

The power communication network carries various power services to ensure the safe operation of the power network, among which, the relay protection service is the most important service. Reasonable planning of the service route can improve the effectiveness and reliability of data transmission in the power communication network, thereby ensuring the reliable operation of the power grid. This paper constructs a route planning architecture for the power communication network based on a software-defined network. On this basis, parameters such as the power service and network-carrying service status are defined. With the goal of minimizing network risk variance and considering link bandwidth utilization and overload constraints of relay protection services, a service route allocation problem has been raised. To solve this problem, a power service route planning scheme based on a reinforcement learning algorithm is proposed. This algorithm uses the state–action–reward–state–action (SARSA) algorithm to complete service route planning. The simulation results show that using the route planning scheme proposed in this paper can avoid the overload of relay protection services, reduce network risk variance, and effectively balance network risk.

Self-Triggered Distributed Formation Control of Fixed-Wing Unmanned Aerial Vehicles Subject to Velocity and Overload Constraints

Self-Triggered Distributed Formation Control of Fixed-Wing Unmanned Aerial Vehicles Subject to Velocity and Overload Constraints

UAV 3D Trajectory Planning and Optimization Using A* Algorithm Based on Free Space Method

Due to the complexity of three-dimensional (3D) map modeling, the A* algorithm is inefficient in planning 3D trajectories for unmanned aerial vehicles (UAVs). This paper designs a method for planning 3D trajectories using A* algorithm based on free space method to address this issue. The method translates the 3D trajectory planning problem into a two-dimensional (2D) trajectory planning problem through flight surface extraction, thereby enhancing the efficiency of trajectory planning. In addition, a trajectory optimization method considering safety parameters and offset costs is designed for the waypoints that fail to meet UAV restrictions. The optimization method consists of longitudinal trajectory altitude adjustment and horizontal trajectory smoothing to ensure the trajectory aligns with the UAV climb rate constraint, normal overload constraint and minimum turning radius constraint. Simulation results show that the designed method delivers higher efficiency in 3D trajectory planning and optimization than the conventional method, and the optimized trajectory adheres to the above constraints.

RESEARCH ON OPTIMAL GUIDANCE LAW WITH LANDING ANGLE CONSTRAINT, 79-85.

As air-to-surface missiles are affected by overload constraints, seekersight angle measurement range, autopilot delay, interference, andother factors, they cannot cause fatal damage to the attacking target.

Three-dimensional coverage-based cooperative guidance law with overload constraints to intercept a hypersonic vehicle

This paper proposes a coverage-based cooperative guidance (CBCG) law to enable low-velocity and constrained-manoeuvrability interceptors to intercept a hypersonic vehicle, considering overload constraints. First, the reachable, feasible, and escape areas are considered to establish the guidance law under a nonlinear interception model. Second, the problem of intercepting the hypersonic vehicle is transformed into a coverage problem by using the coverage strategy. A guidance command including basis and bias terms is generated considering the standard trajectory. The basis term generates the guidance command for nonstandard trajectories to nullify the line-of-sight angular rate at the time of interception to ensure successful interception, and the bias term generates the guidance command for the standard trajectory to enhance the coverage ability of the interceptors. The optimal number and location constraints of the interceptors are theoretically analysed. The effectiveness, applicability, superiority, sensitivity, and robustness of the CBCG law are evaluated through a series of numerical simulations, and its performance is compared with that of the proportional navigation guidance law. The results demonstrate that the CBCG law can ensure that at least one interceptor successfully intercepts the hypersonic vehicle, with high robustness to errors and noise.

Adaptive saturated tracking control for solid launch vehicles in ascending based on differential inclusion stabilization

The large-range uncertainties of specific impulse, mass flow per second, aerodynamic coefficients and atmospheric density during rapid turning in solid launch vehicles (SLVs) ascending leads to the deviation of the actual trajectory from the reference one. One of the traditional trajectory tracking methods is to observe the uncertainties by Extended State Observer (ESO) and then modify the control commands. However, ESO cannot accurately estimate the uncertainties when the uncertainty ranges are large, which reduces the guidance accuracy. This paper introduces differential inclusion (DI) and designs a controller to solve the large-range parameter uncertainties problem. When above uncertainties have large ranges, it can be combined with the ascent dynamic equation and described as a DI system in the mathematical form of a set. If the DI system is stabilized, all the subsets are stabilized. Different from the traditional controllers, the parameters of the designed controller are calculated by the uncertain boundaries. Therefore, the controller can solve the problem of large-range parameter uncertainties of in ascending. Firstly, the ascent deviation system is obtained by linearization along the reference trajectory. The trajectory tracking system with engine parameters and aerodynamic uncertainties is described as an ascent DI system with respect to state deviation, which is called DI system. A DI adaptive saturation tracking controller (DIAST) is proposed to stabilize the DI system. Secondly, an improved barrier Lyapunov function (named time-varying tangent-log barrier Lyapunov function) is proposed to constrain the state deviations. Compared with traditional barrier Lyapunov function, it can dynamically adjust the boundary of deviation convergence, which improve the convergence rate and accuracy of altitude, velocity and LTIA deviation. In addition, the correction amplitudes of angle of attack (AOA) and angle of sideslip (AOS) need to be limited in order to guarantee that the overload constraint is not violated during actual flight. In this paper, a fixed time adaptive saturation compensation auxiliary system is designed to shorten the saturation time and accelerate the convergence rate, which eliminates the adverse effects caused by the saturation. Finally, it is proved that the state deviations are ultimately uniformly bounded under the action of DIAST controller. Simulation results show that the DI ascent tracking system is stabilized within the given uncertainty boundary values. The feasible bounds of uncertainty is broadened compared with Integrated Guidance and Control algorithm. Compared with Robust Gain-Scheduling Control method, the robustness to the engine parameters are greatly improved and the control variable is smoother.

Coverage-based cooperative guidance law for intercepting hypersonic vehicles with overload constraint

This paper studies the problem of multiple interceptors with low velocity, weak maneuverability, and limited overload constraint to cooperatively intercept hypersonic vehicles under a nonlinear interception model. First, a coverage-based cooperative guidance (CBCG) law is proposed based on three concepts, i.e., interceptor reachable area, interceptor feasible area, and hypersonic vehicle escape area. Then, the relationship among the initial location of the interceptors, the parameters of the CBCG law, and the coverage area of the interceptor for intercepting the hypersonic vehicle is analyzed. Next, an allocation algorithm is designed to assign the coverage area and the initial locations of multiple interceptors. Finally, simulations are performed for intercepting the hypersonic vehicle with different maneuverabilities and maneuvering modes, and the proposed CBCG law is compared with the proportional navigation guidance (PNG) and sliding mode control guidance (SMCG) laws. The simulation results show that the proposed CBCG law can ensure that at least one interceptor can accurately intercept the hypersonic vehicle, giving full play of the scale advantage of low-cost interceptors. And the guidance robustness can be guaranteed in the presence of measurement errors.

Cooperative Smooth Nonsingular Terminal Sliding Mode Guidance with Tracking Differentiator for Active Aircraft Defense

Aimed at the poor performance of guidance algorithms designed based on a linearized model in active defense under large leading angle deviation, both-way and one-way cooperative sliding mode guidance algorithms based on the smooth nonsingular terminal sliding mode for the defense missile are proposed. The relative kinematics and linearized models of the target, the active defense missile, and the attacking missile are established. In the design process, two smooth nonsingular terminal sliding mode surfaces are constructed based on zero-effort miss distance and zero-effort velocity, as well as their integral values. A tracking differentiator is introduced for excessive initial command deviation to meet the overload constraints of the active missile and the target. The sensitivity of guidance law to the estimated time-to-go error is reduced, and the target is allowed to perform an independent evasive maneuver. The effectiveness of the proposed guidance strategy is verified by numerical simulation and compared to the existing guidance strategies, the high accuracy, anti-chattering, and strong robustness of the proposed guidance algorithm are verified.

Stochastic AC Transmission Expansion Planning: A Chance Constrained Distributed Slack Bus Approach With Wind Uncertainty

Integrating more renewable energy sources into the grid leads to a more vulnerable power system and presents challenges for power system planners. This paper proposes a probabilistic overload constraint based AC transmission expansion planning model. In terms of economic dispatch, generation adequacy and network constraints are assessed using a probabilistic participation factor power flow. Generation participation factors, which are handled in the AC power flow equations, are used to manage mismatch power that comes from uncertainties as well as transmission loss of the system in a distributed slack bus concept. Combinations of load, wind and N-1 contingency uncertainties are evaluated with Monte Carlo Simulation and the loading limits for the existing and candidate lines and violations on bus voltages are enforced as probabilistic constraints using chance constraint programming. The investment decisions taken under various operating conditions are re-evaluated under a new set of wind power uncertainty that differs from those utilized in the optimization process, and the resulting TEP decisions are analyzed from a risk perspective. The proposed method allows for the uncertain operating conditions to be easily and accurately adapted to the ACTEP optimization. The optimization results show that the participation factor power flow is a promising tool for evaluating probabilistic operating conditions, which can be used to explore the possibility of violations under different uncertainty conditions.

Performance improvement-oriented reentry attitude control for reusable launch vehicles with overload constraint

This paper investigates the issue of reentry attitude control for reusable launch vehicles with overload constraint, and proposes a performance improvement-oriented control scheme. Incorporating the overload constraint into the performance functions, the presented control law proves to guarantee the overload limitation not violating throughout the reentry phase. Compared with traditional performance-guaranteed methods, the presented control introduces a special performance function to achieve better transient performance. Moreover, the attitude control model is reduced to a first-order system with disturbances, leading to a significant reduction of the sophisticated structure by the standard backstepping based approaches. The implementation of the control scheme in the practical engineering is also discussed including the control moment allocation. Simulation results verify the effectiveness of the proposed control approach.

Analysis of Daily Load Patterns Taking into Consideration PEVs Charging Stations in Seoul, South Korea

This paper presents a methodology to calculate daily charging load curves in Seoul, South Korea, by taking into account plug-in electric vehicles (PEVs) charging stations, allowing Seoul’s government to determine the PEVs charging effect on the load. In particular, the study calculates the charging power of uncontrolled PEVs charging in terms of the daily operating characteristics of a vehicle traveling between home and workplace, with respect to PEVs charging stations in the city, according to the PEVs’ market share. For the controlled PEVs charging strategy based on morning and afternoon work-to-home and vice versa traffic characteristics and time-of-use (TOU) prices in Seoul, the study calculates daily load patterns of uncontrolled and controlled charging scenarios. After adding the calculated values to the existing load, the study assesses and compares their effects on the power grid. The results are as follows. If by 2030 the share of electric vehicles is 10%, compared to the existing load, the total load increases by about 13% between 9:00 and 11:00 in the morning for the uncontrolled mode and by about 10% for the controlled mode. The total load increases by about 16% between 20:00 and 22:00 for the uncontrolled mode and 17% for the controlled mode. However, if by 2040 the share of electric vehicles is 30%, compared to the existing load, the total load increases by about 35% between 9:00 and 11:00 in the morning for the uncontrolled mode and by about 32% for the controlled mode. Between 20:00 and 22:00, the uncontrolled mode’s total charging load increases by about 35% and the controlled mode’s total load by about 32%. The analysis also demonstrated that it was possible to achieve a significant load-leveling effect in all charging periods for the controlled mode, with the daily load pattern’s average leveling rate increasing by 8% and 13% in 2030 and 2040, respectively, based on the TOU price system compared with the uncontrolled mode. Based on these results, it is possible to determine the PEVs’ hourly charging load effect on the power grid in Seoul and establish a PEVs charging load management plan to prevent the power grid reinforcement and expansion and to satisfy its overload constraint by using an appropriate TOU price plan.

Study on project trajectory of air-to-ground missile with strapdown seeker under multi constraints

The air-to-ground missile with strapdown seeker may have the problems, including small field of view(FOV), limited overload, and fall angle constraint. To solve the above mentioned problem, a phased guidance scheme is proposed. In this scheme, the attack trajectory is divided into the following six stages, including glided stage, fall angle constraint stage, target acquisition and adjustment stage, terminal guidance stage and blind zone stage. The glided stage is designed to increase range, the terminal fall angle is attained ahead of time at fall angle constraint stage. The aim of target acquisition and adjustment stage is to adjust the missile attitude, so that the target will fall within the FOV of the seeker. It creates good condition to capture the target for strapdown seeker. In the terminal stage, the guidance law of proportional navigation and attitude track are used to fit the needs of FOV constraint and attack accuracy. The simulation result shows that the project trajectory can solve the application of attacking moving targets for air-to-ground missile with strapdown seeker under multi constraints.

A comprehensive coordinated frequency control scheme for double- fed induction generator wind turbine, battery, and diesel generators in islanded microgrids

ABSTRACT This paper proposes a comprehensive strategy for the coordinated frequency control of a low-inertia islanded microgrid (MG). The main components of the MG include a double-fed induction generator (DFIG)-based wind turbine, a battery energy storage system (BESS), and diesel synchronous generators (DGs). In the proposed control framework, effective but simple coordination between the DFIG and the BESS is developed to handle the responsibility of fast-primary frequency support (PFS) and compensate for the deficiencies of DGs in providing the fast frequency response during sudden load disturbances. To minimize the consumption of BESS energy, the proposed coordinated control utilizes the maximum support capacity of the DFIG bound by the over-deceleration (OD) and overload (OL) constraints. The coordinated BESS prevents the OD and OL issues of DFIG during the support period, and compensates the shortages of the DFIG wind system for the certain frequency support under any wind condition. It also prevents the secondary frequency drop issue during the DFIG rotor speed recovery. To return to the normal condition after fulfilling the PFS functions, the DFIG and BESS support powers are brought back to zero via a secondary frequency control (SFC) applied in the DGs. In normal conditions, to optimally manage the MG energy efficiency, the BESS exchanged power is set to zero, and the DFIG is controlled in the maximum power point tracking (MPPT) operation through an efficient algorithm. A test system with a 33% load disturbance is modeled in a detailed time-domain simulation environment to evaluate and verify the effectiveness of the proposed design methodology. The simulation results show the superiority of the proposed coordinated control strategy compared with only DFIG or only BESS control under various wind conditions.

SWIPT-Enabled Cooperative NOMA With mth Best Relay Selection

Non-orthogonal multiple access (NOMA) was recently regarded as a potential technique for next generation wireless networks. Recent works on relay selection for cooperative NOMA systems have mainly addressed the best relay selection to forward its received signals to terminal nodes. Nonetheless, in practical scenarios, the best relay may be unavailable due to non-ideal conditions such as scheduling and overload constraints or possibly due to channel feedback delay. Therefore, there is compelling need to consider a more practical solution, in which the best available relay is selected. In this article, we examine the error rate performance for simultaneous wireless information and power transfer (SWIPT)-enabled NOMA, while considering the selection of the m th best available relay. In particular, we present an exact pairwise error probability (PEP) expression to obtain a bit error rate (BER) upper bound. The asymptotic PEP is investigated to evaluate the achievable diversity order for NOMA users. Finally, simulation results are provided to verify the accuracy of the derived PEP expressions and to give more insights into the system performance.

전기차 충전 장소를 고려한 그리드 일부하곡선 분석

This paper presents a methodology to calculate the daily load curve per city by taking into consideration a charging station for electric vehicles, which easily determines the effect of the load owing to the charging of electric vehicles in Seoul. In particular, we calculate the charging power of uncontrolled plug-in electric vehicles (PEVs) in terms of the daily running characteristics of vehicle travelling between homes and workplace, with respect to PEV charging stations in the city, according to the market share of PEVs. Furthermore, we calculate the load curve for the simultaneous charging strategy of controlled PEVs in terms of the vehicles’ daily running characteristics between homes and workplaces and a time-of-use (TOU) price plan of the Seoul Metropolitan Government under uncontrolled and controlled charging types. Thus, we are able to analysis the effect of the total existing electricity load and the abovementioned daily load on the grid. Because we can precisely determine the effect of the hourly charging load of PEVs on a power grid in Seoul using these study results, we can establish a PEV charging load management plan to prevent power grid reinforcement and expansion while satisfying the overload constraint of the power grid in Seoul using an appropriate TOU price plan.

Enhancing Event-Driven Load Shedding by Corrective Switching With Transient Security and Overload Constraints

Enhancing Event-Driven Load Shedding by Corrective Switching With Transient Security and Overload Constraints

Sparsity-promoting distributed charging control for plug-in electric vehicles over distribution networks

Uncoordinated charging of plug-in electric vehicles brings a new challenge on the operation of a power system as it causes power flow fluctuations and even unacceptable load peaks. To ensure the stability of power network, plug-in charging needs to be scheduled against the base load properly. In this paper, we propose a sparsity-promoting charging control model to address this issue. In the model, the satisfaction of customers is improved through sparsity-promoting charging where the numbers of charging time slots are optimized. Dynamic feeder overload constraints are imposed in the model to avoid any unacceptable load peaks, and thus ensure the network stability. Then, a distributed solution strategy is developed to solve the problem based on the alternating direction method of multipliers (ADMM) since most of power networks are managed typically in a distributed manner. During solving process, Lagrangian duality is used to transform the original problem into an equivalent dual problem, which can be decomposed into a set of homogeneous small-scaled sub-problems. Particularly, each sub-problem either has a closed-form solution or can be solved locally by an accelerated dual gradient method. The global convergence of the proposed algorithm is also established. Finally, numerical simulations are presented to illustrate our proposed method. In contrast to traditional charging models, our sparsity-promoting charging model not only ensures the stability of power network, but also improves the satisfaction of customers.

Multiobjective Optimization of Multistage Synchronous Induction Coilgun Based on NSGA-II

The structure and trigger control strategy have become the most important factors that restrict the performance of the multistage synchronous induction coilgun (MSSICG). However, it is still a difficult task to design MSSICG under overload constraint due to coupling between the multiple parameters. In this paper, the maximization of the emission efficiency and acceleration stationarity is treated as a multiobjective optimization problem. By analyzing the relationship between the number of turns and the other structural parameters of the launch, the multiobjective optimization model of MSSICG is established by the current filament method which was verified by the experimental data and finite-element method. And then the second generation nondominated sorting genetic algorithm (NSGA-II) and multiobjective particle swarm optimization (MOPSO) were employed to optimize the model in order to maximize the energy transfer efficiency while achieving the smooth acceleration of the armature. With the formulated optimization model, a five-stage synchronous induction coilgun is optimized as a special case. A decision-making procedure based on the fuzzy membership function is used for obtaining best compromise solution from the set of Pareto-solutions obtained through NSGA-II and MOPSO. In addition, the optimization performance of the proposed multiobjective optimization model and the single-objective optimization model of the MSSICG was compared. The result of optimization shows that the proposed multiobjective optimization model of MSSICG can effectively improve the performance of the coilgun compared with the single-objective optimization model which takes of the launch velocity and overload acceleration as the combination objective function or only the launch velocity.