基于UVM Phases的数字IC复位验证

数字IC设计验证过程中,确保数字IC设计在上电后(Power-On)或出现错误后能通过复位进入一个的确定的初始状态,是设计功能正确实现的基础。验证人员需要编写测试用例,以验证各种不同场景下复位后设计的正确性和可靠性,复位验证是验证工作中必不可少的关键环节之一。UVM是近年来广泛采用的一种通用验证方法学,UVM中的phases机制为各个验证环境中各个组件提供了一个层次化的同步机制。UVMphases的跳跃(phase jump)能力,由于其原生所具备的自动终止phase相关线程和测试序列(UVMsequence)并且跳转至测试过程中特定phase的功能,可以被用于开发通用、标准化的复位验证环境。

Real-Time Detection for Magnetic Island of Neoclassical Tearing Mode in EAST Plasma Control System

Accurate detection of a magnetic island in real time is one of the important issues for the tearing mode（TM） and neoclassical tearing mode（NTM） control.This paper presents a real-time detection system for the magnetic island of NTM control in the EAST Plasma Control System（PCS）.Diagnosis is based on magnetic periodic perturbation and electron temperature fluctuation caused by the magnetic island.Therefore,a Mirnov measurement has been selected to calculate the island＇s parameters,such as island width,frequency of island rotation,and toroidal number.The electron cyclotron emission（ECE） system can detect the island position,which is calculated by two fast detection algorithms called correlation analysis and Hilbert transform.For future NTM control,real-time equilibrium reconstruction（rt-EFIT） is needed to locate the rational q-surface where the island is detected.This fast detection system is able to detect an island within 3 ms.It can be integrated into PCS to provide effective parameters of the island for NTM control by using EC resonance heating（ECRH） in the next experiment of EAST.

FRT Control Method Including Islanding Detection in PCS Model for Photovoltaic Generation

The experimental results by the simulated PV （photovoltaic） system for understanding the cause of disconnection when instantaneous voltage sag occurs are reported in this study. Moreover, it is understood that the PCS with the voltage phase jump detection method which is one of the main causes of the disconnection. We modeled it in the simulation. When fault occurs, even though the residual voltage is more than 20% and the voltage sag time is within 1.0 s, the PCS disconnected by the voltage phase jump detection was confirmed in the simulation results. Ifa large number of PV systems are interconnected in the power system, this study is verified through the simulation that the interaction caused by the disconnection which generated by the voltage phase jump detection. This study is proposed threshold limit value of islanding detection. The validity of proposed method was verified through the simulation in this study.

Voltage phase angle jump characteristic of DFIGs in case of weak grid connection and grid fault

In the condition of connecting large scale doubly-fed induction generators (DFIGs) into weak grid,the closely coupled interactions between wind generators and power grid becomes more severe.Some new fault characteristics including voltage phase angle jump will emerge,which will influence the power quality of power system.However,there are very few studies focusing on the mechanism of voltage phase angle jump under grid fault in a weak grid with wind turbine integration.This paper focuses on the scientific issues and carries out mechanism studies from different aspects,including mathematical deduction,field data analysis and time domain simulation.Based on the analysis of transientcharacteristics of DFIGs during the grid fault,this paper points out that the change of terminal voltage phase angle in DFIGs is an electromagnetism transition process,which is different from conventional synchronous generator.Moreover,the impact on transient characteristics of voltage phase angle are revealed in terms of fault ride through(FRT) control strategies,control parameters of current inner-loop of rotor-side converter and grid strength.

Fault Ride Through Strategy of DFIG Using Rotor Voltage Direct Compensation Control Under Voltage Phase Angle Jump

Wind power has developed rapidly in recent years,and large-scale wind power facilities connected to power grids will bring many new challenges.Some new operation charac-teristics of power grids with doubly-fed induction generator(DFIG)may exhibit,for example voltage phase angle jumps(VPAJ).VPAJ can negatively impact the fault ride through(FRT)performance of DFIG.This paper firstly investigates the physical mechanism and the operation characteristics of DFIG with VPAJ.It is noted that the current control strategies designed for voltage amplitude changes are not suitable for VPAJ.Secondly,the paper develops an FRT optimization control strategy under VPAJ which optimizes the DFIG operation characteristics.Finally,simulations of a 250 MW wind farm are presented which validate the proposed FRT strategy.

Transient characteristics and adaptive fault ride through control strategy of DFIGs considering voltage phase angle jump

Wind power in China has experienced fast development in recent years. However, areas rich in wind power resources are often far away from loads centers,which leads to weak connection between wind turbines and power grid. When a grid fault occurs, new transient characteristics in weak grid integrated with doubly-fed induction generators(DFIGs) may present, such as voltage phase angle jump. Current control strategies for wind turbine with strong grid connection are hard to be adapted under weak gird connection. This paper explores the transient characteristics of DFIGs under voltage phase angle jump through analyzing the operation and control characteristics of DFIGs connected into weak grid when the voltage phase angle jumps. Fault ride through(FRT) control strategy of DFIGs based on adaptive phase-locked loop is proposed to adapt weak grid condition. The reference frame of the proposed strategy will be changed in real-time to track the operation condition of DFIGs according to the terminal voltage, and different phase tracking method is adopted during the grid fault. Field data analysis and time domain simulation are carried out. The results show that voltage phase angle jumps when a grid fault occurs, which weakens the FRT capability of DFIGs, and the proposed FRT control strategy can optimize transient characteristics of DFIGs, and improve the FRT capability of DFIGs.

Adaptive Observer for Dynamic Voltage Restorer with Optimized Proportional Integral Gains

An algorithm based on a sliding-mode adaptive observer is proposed for the effective control of dynamic voltage restorers(DVRs).Three single-phase voltage source converter-based topologies are implemented for the DVR.In this control,frequency adaption is considered for estimating the phase angle,system frequency,and fundamental component of the disturbed input voltage signals.The estimated fundamental component of the supply voltage is used to generate the DVR reference load voltage.The phase jump in the supply voltage is also considered for DVR compensation studies along with voltage sag,swell,and voltage distortions.For this purpose,the gains of the proportional integral(PI)controllers used in this control algorithm are estimated using a nature-inspired optimization approach for the desired response.A moth flame optimization algorithm is implemented for PI controller gain tuning owing to the advantage of finding the best solution by each moth’s search and updating it.Through Matlab simulation and hardware testing,the performance of the DVR with an adaptive observer is found to be satisfactory for supply voltage sag,swell,phase jump,and voltage distortions.