scholarly journals Hopf Bifurcation and Parameter Sensitivity Analysis of a Doubly-Fed Variable-Speed Pumped Storage Unit

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 204
Author(s):  
Zhiwei Zhu ◽  
Xiaoqiang Tan ◽  
Xueding Lu ◽  
Dong Liu ◽  
Chaoshun Li
Keyword(s):  
Renewable Energy ◽  
Hopf Bifurcation ◽  
Transfer Coefficient ◽  
Stability Domain ◽  
State Variables ◽  
Variable Speed ◽  
Storage Unit ◽  
Doubly Fed ◽  
Pumped Storage ◽  
The Stability

The doubly-fed variable speed pumped storage unit is a storage system suitable for joint operation with renewable energy sources to smooth the imbalance between renewable energy supply and electricity demand. However, its working principle and operation control are more complex than those of constant speed pumped storage. In this study, a nonlinear model of doubly-fed variable speed pumped storage units (VSPSUs) considering nonlinear characteristics of the head loss is established. The study finds that a supercritical Hopf bifurcation occurs in the system, and the area enclosed by the lower side of the bifurcation line and the coordinate axis is the stability domain of the system. The active power step perturbation from −0.3 to 0.3 will gradually reduce the area of the stability domain and narrow the adjustable range of the control parameters. In addition, the sensitivity of the model full state variables and the primary and secondary relationships to the changes of subsystem parameters is analyzed systematically using the trajectory sensitivity. It is found that there is a large difference in the sensitivity of different state variables to the parameters. The state variables are much more sensitive to the transfer coefficient of hydraulic turbine torque to guide vane opening, the unit inertia time constant, and the controller proportional gain change than other parameters, which are defined as highly sensitive parameters. The receiver response time constant and the turbine flow-to-head transfer coefficient are the corresponding low-sensitivity parameters.

scholarly journals Research on variable speed operation of static frequency converter for pumped storage units

2021 ◽  
Vol 252 ◽  
pp. 02022
Author(s):  
Haoyuan Li ◽  
Guanjun Li ◽  
Bo Yang ◽  
Liantao Ji
Keyword(s):  
Storage Systems ◽  
Frequency Converter ◽  
Storage System ◽  
Input Power ◽  
Variable Speed ◽  
Storage Unit ◽  
Advantages And Disadvantages ◽  
Doubly Fed ◽  
Pumped Storage ◽  
Storage Units

Constant speed pumped storage unit is widely used, however it cannot adjust the input power when working in the electric mode, and cannot work in the best efficiency when the head of the reservoir changes greatly. Therefore, it is necessary to study and develop the variable speed pumped storage systems. This paper has studied on variable speed operation of static frequency converter for pumped storage units. Besides, development status of variable speed pumped storage system at home and abroad is investigated. Furthermore, classification and advantages and disadvantages of variable speed pumped storage system are also introduced, mainly including two typical variable speed pumped storage systems, i.e., doubly-fed variable speed system and full power variable speed system.

scholarly journals Modelling and Simulation of Doubly-Fed Variable-Speed Pumped Storage Unit

2018 ◽  
Vol 189 ◽  
pp. 022003 ◽  
Author(s):  
Zheng Tan ◽  
Lili Hao ◽  
Tingting Liang ◽  
Tao Wu ◽  
Shanying Li ◽  
...  
Keyword(s):  
Modelling And Simulation ◽  
Variable Speed ◽  
Storage Unit ◽  
Doubly Fed ◽  
Pumped Storage

scholarly journals Analysis of Control Characteristics and Design of Control System Based on Internal Parameters in Doubly Fed Variable-Speed Pumped Storage Unit

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-23
Author(s):  
Guopeng Zhao ◽  
Yongxin Zhang ◽  
Jiyun Ren
Keyword(s):  
Control Strategy ◽  
Control Strategies ◽  
Variable Speed ◽  
Pump Mode ◽  
Storage Unit ◽  
Control Block ◽  
Internal Parameters ◽  
Generating Mode ◽  
Doubly Fed ◽  
Pumped Storage

In this paper, the control strategies and their characteristics when applied to the doubly-fed variable-speed pumped storage unit in generating mode and pump mode are discussed. The composition of doubly fed variable-speed pumped storage unit is introduced, and the mathematical model of every component is proposed. Two control strategies of the unit are introduced. One is the power priority control strategy and the other is the speed priority control strategy. Then, the control block diagrams of the two control strategies in the generating mode and the pump mode are established, and the parameters of the unit in each control strategy are designed. The two control strategies are simulated in power generation and pumping conditions. Finally, the conclusion that power priority strategy has a better effect on power control is obtained.

scholarly journals Characteristics Analysis and Fuzzy Fractional-Order PID Parameter Optimization for Primary Frequency Modulation of a Pumped Storage Unit Based on a Multi-Objective Gravitational Search Algorithm

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 137 ◽  
Author(s):  
Xin Wu ◽  
Yanhe Xu ◽  
Jie Liu ◽  
Cong Lv ◽  
Jianzhong Zhou ◽  
...  
Keyword(s):  
Fractional Order ◽  
Pid Controller ◽  
Search Algorithm ◽  
Gravitational Search Algorithm ◽  
Storage Unit ◽  
Water Head ◽  
Pumped Storage ◽  
The Stability ◽  
Primary Frequency ◽  
Fractional Order Pid

Compared with conventional hydropower units, the pumped storage unit has the characteristics of diverse working conditions and frequent switching. Therefore, the stability and regulation quality of the primary frequency modulation transition process of the regulating system is very important. Due to the “S” characteristics of the pumped storage unit (PSU), the pumped storage unit regulating system has a strong nonlinearity, and the conventional proportional-integral-derivative (PID) controller cannot provide high-quality control under low water head conditions. In this paper, the nonlinear PSU model with an elastic water hammer effect is studied, and the fuzzy fractional-order PID (FFOPID) controller is designed to improve the stability of the system. The membership function and the control parameters of the fractional-order PID are optimized based on the multi-objective gravitational search algorithm (MOGSA). The experimental results show that the optimized design of the FFOPID controller has better control quality than the traditional PID controller, the fractional-order PID (FOPID) controller, and the fuzzy PID controller (FPID) when the system is disturbed by the rotating speed under low water head.

τ-D Decomposition to the One Dimensional Delay Differential Equation by Fixed the Coefficient b<0

2013 ◽  
Vol 785-786 ◽  
pp. 1418-1422
Author(s):  
Ai Gao
Keyword(s):  
Differential Equation ◽  
Hopf Bifurcation ◽  
Delay Differential Equation ◽  
Stability Domain ◽  
Transcendental Equation ◽  
One Dimension ◽  
One Dimensional ◽  
The Stability ◽  
The One ◽  
Delay Differential

In this paper, we provide a partition of the roots of a class of transcendental equation by using τ-D decomposition ,where τ>0,a>0,b<0 and the coefficient b is fixed.According to the partition, one can determine the stability domain of the equilibrium and get a Hopf bifurcation diagram that can provide the Hopf bifurcation curves in the-parameter space, for one dimension delay differential equation .

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