Time-varying parameters estimation with adaptive neural network EKF for missile-dual control system

In this paper, a filtering method is presented to estimate time-varying parameters of a missile dual control system with tail fins and reaction jets as control variables. In this method, the long-short-term memory(LSTM) neural network is nested into the extended Kalman filter(EKF) to modify the Kalman gain such that the filtering performance is improved in the presence of large model uncertainties. To avoid the unstable network output caused by the abrupt changes of system states,an adaptive correction factor is introduced to correct the network output online. In the process of training the network, a multi-gradient descent learning mode is proposed to better fit the internal state of the system, and a rolling training is used to implement an online prediction logic. Based on the Lyapunov second method, we discuss the stability of the system, the result shows that when the training error of neural network is sufficiently small, the system is asymptotically stable. With its application to the estimation of time-varying parameters of a missile dual control system, the LSTM-EKF shows better filtering performance than the EKF and adaptive EKF(AEKF) when there exist large uncertainties in the system model.

Dual Control of Depositional Facies on Uranium Mineralization in Coal-bearing Series： Examples from the Tuanyushan Area of the Northern Qaidam Basin, NW China

The uranium deposits in the Tuanyushan area of northern Qaidam Basin commonly occur in coal-bearing series. To decipher the U-enrichment mechanism and controlling factors in this area, a database of 72 drill cores, including 56 well-logs and 3 sampling wells, was examined for sedimentology and geochemistry in relation to uranium concentrations. The results show that coal-bearing series can influence uranium mineralization from two aspects, i.e., spatial distribution and dynamic control. Five types of uranium-bearing rocks are recognized, mainly occurring in the braided river and braided delta sedimentary facies, among which sandstones near the coals are the most important. The lithological associations of sandstone-type uranium deposits can be classified into three subtypes, termed as U-coal type, coal-U-coal type, and coal-U type, respectively. The coal and fine siliciclastic rocks in the coal- bearing series confined the U-rich fluid flow and uranium accumulation in the sandstone near them. Thus, the coal-bearing series can provide good accommodations for uranium mineralization. Coals and organic matters in the coal-bearing series may have served as reducing agents and absorbing barriers. Methane is deemed to be the main acidolysis hydrocarbon in the U-bearing beds, which shows a positive correlation with U-content in the sandstones in the coal-bearing series. Additionally, the 613C in the carbonate cements of the U-bearing sandstones indicates that the organic matters, associated with the coal around the sandstones, were involved in the carbonation, one important component of alteration in the Tuanyushan area. Recognition of the dual control of coal-bearing series on the uranium mineralization is significant for the development of coal circular economy, environmental protection during coal utilization and the security of national rare metal resources.

Innovations twostage dual control

A novel dual control method is proposed for the stochastic systems with unknown parameters, which converts the unsolvable dynamic programming problem into a tractable twostep ahead minimum variance control problem in a stochastic suboptimal view. Innovation variance is used to improve the learning effect, and the instant weight is introduced to reduce the influence of the future output estimation error on the system. Simulation results show the satisfactory performance of the new controller.

“Dual control” for quality-critical yarns

Total Contamination Control helps Texhong Group to be recognized in a new market One of the top ten spinning mills in China,Texhong Group has grown steadily since its establishment in1997,building a reputation for high value-added products in challenging market sectors such as

Unified Smith Predictor Based H_∞ Wide-Area Damping Controller to Improve the Control Resiliency to Communication Failure

Inter-area low frequency oscillation in power system is one of the major problems for bulk power transmission through weak tie lines.Use of wide-area signal is more effective than the local area signal in damping out the inter-area oscillations.Wide area measurement system(WAMS)is convenient to transmit the wide area signal through the communication channel to the remote location.Communication failure is one of the disastrous phenomena in a communication channel.In this paper,a dual input single output(DISO)Hm controller is designed to build the control resiliency by employing two highest observability ranking wide area signals with respect to the critical damping inter-area mode.The proposed controller can provide sufficient damping to the system and also the system remains stabilized if one of the wide-area signals is lost.The time delay is an unwanted phenomenon that degrades the performance of the controllers.The unified Smith predictor approach is used to design a Hm controller to handle the time delay.Kundur's two-area and IEEE-39 bus test systems are considered to verify the effectiveness of the proposed controller.From the simulation results,it is verified that,the proposed controller provides excellent damping performance at normal communication and improves the controller resiliency to counteract the communication failure.

Vector Control of the Single-Phase Inverter Based on the Extended and Virtual Circuits

A vector control based on the extended equivalent circuit and virtual circuits is proposed for the single-phase inverter.By the extended circuit,the other two phase voltages can be extended by the output voltage of the single-phase inverter so as to construct the voltage vector.The voltage outer-loop is to control the voltage vector in dq coordinate system,and the output voltage can track the target value without deviation in steady state.By designing the virtual circuit,the voltage inner-loop can achieve approximate decoupling and improve the dynamic response under the changeable load.Compared with the traditional dual closed-loop control,the proposed dual closed-loop control scheme only needs to detect and control the voltage without the current.It not only can achieve good control effect,but also reduce the complexity of the hardware.Finally,the simulation and experimental results show that the single-phase inverter has good static and dynamic characteristics regardless of stable load or changeable load.

Energy management with dual droop plus frequency dividing coordinated control strategy for electric vehicle applications

In this paper,a dual droop-frequency diving coordinated control strategy is proposed for electric vehicle(EV)applications,where the hybrid energy storage system(HESS)with supercapacitors and batteries is integrated to prolong the life time of storage elements.The dynamic power allocation between the supercapacitor and batteries are obtained through the voltage cascaded control,upon which the high and low frequency power fluctuation are absorbed by the supercapacitors and batteries respectively to fully exploit the advantages of the supercapacitors and batteries.Moreover,the power capacity is scaled up by connecting storage blocks in parallel.A dual droop control scheme for parallel-connected energy storage system and its operation principle is introduced on the aspect of current sharing characteristic and state-of-charging(SOC)management.After detailed analysis and formula derivation,the corresponding loop parameters are designed.Through this control method,the current sharing performance is ensured and each block makes the self-adaptive adjustment according to their SOC.Consequently,the load power can be shared effectively,which helps to avoid the over-charge/over-discharge operation and contributes to the life cycle of the energy storage system.Each module is autonomous controlled without the necessity of communication,which is easy,economic and effective to realize.Finally,the simulation and experimental results are exhibited to verify the effectiveness of the proposed control scheme.

Autonomous Dual Active Power-frequency Control in Power System with Small-scale Photovoltaic Power Generation

Active power control of the photovoltaic(PV)power generation system is a promising solution to regulate frequency fluctuation in a power system with high penetration of renewable energy.This paper proposes an autonomous active power control of a small-scale PV system for supporting the inertial response of synchronous generators and power-frequency control.In the proposed control approach,an effective grid frequency regulation scheme is realized using slow-and fast-frequency responses.A low-pass filter based frequency measurement is used for slow-frequency response,while direct frequency measurement is used for fast-frequency response.The designed dual droop characteristic-based control is shaped to achieve a smooth transition between slow-and fast-frequency responses.The performance of the proposed control approach is demonstrated for serious disturbance scenarios,i.e.,considerable power-load imbalance and generation trip.In the powerload imbalance test scenario,the proposed control approach works properly within the normal frequency deviation region even when the frequency deviation exceeds that region occasionally.In the generation trip test,the frequency deviation is mitigated quickly,and the employed droop control is smoothly transferred from the slow-to fast-frequency responses.

A Photovoltaic Generation System Based on Wide Voltage-Gain DC-DC Converter and Differential Power Processors for DC Microgrids

In this paper,a photovoltaic(PV)generation system based on front-stage differential power processors(DPP)and BACK-stage centralized wide voltage-gain converter is proposed.The resonant switched capacitor(ReSC)converter,which features high power density and high efficiency,is employed as the differential power processor and aims at processing the differential power among series-connected PV modules,avoiding the great power loss caused by power mismatch of PV modules.The ReSC converter in PV system can operate in equalization mode or MPPT mode and both modes are researched.The BACK-stage DC-DC converter is implemented as the dual-phase-shift controlled full-bridge converter(DPS-FBC).It has high conversion efficiency and wide voltage gain,suitable for PV generation applications.The current source control for grid-connected mode and the voltage source control for islanding mode are developed for DPS-FBC.Therefore,for the whole system with front and BACK stage converters,the dual-mode control strategy is proposed.When the system is connected to the grid,DPS-FBC operates as the current source for global MPPT for PV modules while ReSC converters operate in maximum power point tracking(MPPT)mode for local MPPT.When the system operates in an island,DPS-FBC works as the voltage source for constant output voltage control and ReSC converters work in equalization mode.The mode switch is based on the voltage of output DC bus.Simulations and experiments verify the feasibility of the proposed PV generation system and the effectiveness of the proposed control algorithm.