scholarly journals Active Power Control of Hydraulic Wind Turbines during Low Voltage Ride-Through (LVRT) Based on Hierarchical Control

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1224
Author(s):  
Chao Ai ◽  
Guangling Zhou ◽  
Yalun Wang ◽  
Wei Gao ◽  
Xiangdong Kong
Keyword(s):  
Wind Turbines ◽  
Control Method ◽  
Low Voltage ◽  
Minimum Energy ◽  
Hierarchical Control ◽  
Programming Algorithm ◽  
Control Law ◽  
Energy Regulation ◽  
Low Voltage Ride Through ◽  
The Impact

To improve the power grid adaptability and low voltage ride-through (LVRT) capability of hydraulic wind turbines (HWT), an LVRT control method based on hierarchical control is proposed for the energy regulation of HWT. The method includes a top-level machine-controlled paddle, mid-level control based on variable motor swash plate angle, and an underlying control based on throttle opening. To achieve multivariable coordinated control of the HWT via the control process, the minimum wind, maximum inertial energy storage, and minimum energy consumption of the throttle valve of the wind turbine are optimized. The multiobjective control law is computed by a quadratic programming algorithm, and the optimal control law is obtained. The multitarget control strategy is simulated and analyzed by AMESim14 and MATLAB/Simulink R2014a software, and the control law is verified by a semiphysical test platform of an HWT. The results show that the proposed control method can effectively reduce the residual energy of the HWT during LVRT, reduce the impact on the generator, and improve the adaptability of the HWT.

Low Voltage Ride through (LVRT) Control of Double-Fed Wind-Driven Generator

2012 ◽  
Vol 499 ◽  
pp. 400-404
Author(s):  
Jian Hong Zheng ◽  
Jie Feng Li ◽  
Yu Zhi Gao
Keyword(s):  
Power System ◽  
Wind Turbine ◽  
Wind Power ◽  
Control Method ◽  
Low Voltage ◽  
Voltage Drop ◽  
Power Grid ◽  
Rapid Development ◽  
Low Voltage Ride Through ◽  
The Impact

With the rapid development of the wind power, it is no longer an isolated power system and gradually incorporated in the local power grid. However, as the increasing proportion of the installed wind power capacity in the power grid, the affection of the wind turbine to the region power system is getting heavier, which inevitably bring some new problems to the power system. The low voltage ride through (LVRT) is the direct embodiment of the power quality. In this paper, we fist analyze the impact of the voltage drop on the double-fed wind turbine. Then, a LVRT control method is proposed based on hardware realization. The detailed explanation of the proposed control method is given at last.

scholarly journals Secondary Control for Storage Power Converters in Isolated Nanogrids to Allow Peer-to-Peer Power Sharing

Electronics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 140 ◽  
Author(s):  
Eva González-Romera ◽  
Enrique Romero-Cadaval ◽  
Carlos Roncero-Clemente ◽  
Mercedes Ruiz-Cortés ◽  
Fermín Barrero-González ◽  
...  
Keyword(s):  
Power Flow ◽  
Control Method ◽  
Low Voltage ◽  
Hierarchical Control ◽  
Power Converter ◽  
Power Sharing ◽  
Primary Control ◽  
Secondary Control ◽  
Control Loops ◽  
Energy Interchange

It is usual in literature that power sharing among grid-forming sources of an isolated microgrid obeys their energy rating, instead of economic agreements between stakeholders, and circulating energy among them is usually avoided. However, these energy interchanges make strong sense and classical power sharing methods must be reformulated in the context of prosumer-based microgrids. This paper proposes a secondary control method for a prosumer-based low-voltage nanogrid that allows for energy interchange between prosumers, where storage systems, together with PV generators, are the controllable grid-forming sources. A power flow technique adapted to islanded microgrids is used for secondary control algorithm and the whole hierarchical control strategy for the prosumer converter is simulated and validated. This hierarchical control consists of three stages: tertiary control plans the energy interchange among prosumers, secondary obtains different voltage and power setpoints for each of the grid-forming sources, and, finally, primary control guarantees stable voltage and frequency values within the nanogrid with droop rules. Inner control loops for the power converter are also defined to track setpoints and assure stable performance. Simulation tests are carried out, which prove the stability of the proposed methods and the accuracy of the setpoint tracking.

Dynamic Programming Approach for Online Freeway Flow Propagation Adjustment

2002 ◽  
Vol 1802 (1) ◽  
pp. 263-270 ◽  
Author(s):  
Xuesong Zhou ◽  
Hani S. Mahmassani
Keyword(s):  
Dynamic Programming ◽  
Control Method ◽  
Dynamic Programming Algorithm ◽  
Superior Performance ◽  
Programming Algorithm ◽  
Programming Approach ◽  
Base Case ◽  
Solution Quality ◽  
Flow Propagation ◽  
The Impact

An optimization framework for online flow propagation adjustment in a freeway context was proposed. Instead of performing local adjustment for individual links separately, the proposed framework considers the interconnectivity of links in a traffic network. In particular, dynamic behavior in the mesoscopic simulation is approximated by the finite-difference method at a macroscopic level. The proposed model seeks to minimize the deviation between simulated density and anticipated density. By taking advantage of the serial structure of a freeway, an efficient dynamic programming algorithm has been developed and tested. The experiment results compared with analytic results as the base case showed the superior performance of dynamic programming methods over the classical proportion control method. The effect of varying update intervals was also examined. The simulation results suggest that a greedy method considering the impact of inconsistency propagation achieves the best trade-off in terms of computation effort and solution quality.

scholarly journals Improved Control Strategy of MMC–HVDC to Improve Frequency Support of AC System

2020 ◽  
Vol 10 (20) ◽  
pp. 7282
Author(s):  
Zicong Zhang ◽  
Junghun Lee ◽  
Gilsoo Jang
Keyword(s):  
Wind Turbines ◽  
Wind Farm ◽  
Control Method ◽  
Short Circuit ◽  
Synchronous Generator ◽  
Frequency Stability ◽  
Offshore Wind ◽  
Inertial Response ◽  
Control Evaluation ◽  
The Impact

With the continuous development of power electronics technology, variable-speed offshore wind turbines that penetrated the grid system caused the problem of inertia reduction. This study investigates the frequency stability of synchronous, offshore wind-farm integration through a modular-multilevel-converter high-voltage direct-current (MMC–HVDC) transmission system. When full-scale converter wind turbines (type 4) penetrate the AC grid, the AC system debilitates, and it becomes difficult to maintain the AC system frequency stability. In this paper, we present an improved inertial-response-control method to solve this problem. The mathematical model of the synchronous generator is based on the swing equation and is theoretically derived by establishing a MMC–HVDC. Based on the above model, the inertia constant is analyzed using a model that integrates the MMC–HVDC and offshore synchronous generator. With the new improved control method, a more sensitive and accurate inertia index can be obtained using the formula related to the effective short-circuit ratio of the AC system. Moreover, it is advantageous to provide a more accurate inertial control evaluation for AC systems under various conditions. Furthermore, the impact of the MMC–HVDC on system safety is assessed based on the capacitor time constant. This simulation was implemented using the PSCAD/EMTDC platform.

A Cut-Out Strategy for Wind Turbines that Ensures Low-Voltage Ride-Through Capability

2020 ◽  
Vol 15 (4) ◽  
pp. 1567-1575
Author(s):  
Aiguo Tan ◽  
Zhihan Tang ◽  
Xianbo Sun ◽  
Jianwei Zhong ◽  
Honghua Liao ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Low Voltage ◽  
Low Voltage Ride Through

scholarly journals Research and application of low voltage ride through capability of wind turbines in microgrid

2019 ◽  
Vol 631 (4) ◽  
pp. 042031
Author(s):  
Guanglei Li ◽  
Shuai Yuan ◽  
Fei Jin ◽  
Xiaoliang Liu ◽  
Peng Zhao
Keyword(s):  
Wind Turbines ◽  
Low Voltage ◽  
Low Voltage Ride Through
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