检索结果-内蒙古大学图书馆

A Method to Improve the Dynamic Performance of Moving Average Filter-Based PLL

IEEE TRANSACTIONS ON power ELECTRONICS 2015年第10期30卷 5978-5990页

作者： Wang, Jinyu Liang, Jun Gao, Feng Zhang, Li Wang, Zhuodi Shandong Univ Minist Educ Key Lab Power Syst Intelligent Dispatch & Control Jinan 250061 Peoples R China

Phase-locked loop (PLL) technique is widely used for synchronization applications. A variety of moving average filter (MAF)-based PLLs have been presented in recently published literatures. MAF-based PLL can completely eliminate the effect of unbalanced voltage, characteristic harmonics, and dc offset. Unfortunately, the open-loop bandwidth is drastically reduced after incorporating MAF into the PLL structure. The problem is analyzed in detail in this paper, and it is proved to be caused by the large MAF window width which is determined by the lowest order harmonic. Then, an improved method named differential MAF-PLL (DMAF-PLL) is proposed. This method can rapidly eliminate the lowest order harmonic to narrow the MAF window width. DMAF-PLL is realized by incorporating a special proportional component into the MAF-based PLL. The special proportional component can online change its value according to the frequency of input signal, and it will not introduce phase lag, so as not to deteriorate the stability of PLL. DMAF-PLL increases the open-loop bandwidth and greatly improves the dynamic performance of MAF-based PLL, and it is easy to be implemented with low computational burden. DMAF-PLL can be used in both three-phase and single-phase voltage systems. Simulation and experimental results are included to validate the effectiveness and robustness of the proposed method.

关键词： Bandwidth dynamic response grid synchronization moving average filter phase-locked loop (PLL)

来源：评论

学校读者我要写书评

暂无评论

Day-Ahead Optimal dispatch Strategy for Active Distribution Network Based on Improved Deep Reinforcement Learning

引用

IEEE ACCESS 2022年 10卷 9357-9370页

作者： Li, Xiaoyu Han, Xueshan Yang, Ming Shandong Univ Minist Educ Key Lab Power Syst Intelligent Dispatch & Control Jinan 250061 Peoples R China

To effectively deal with the challenge of optimal dispatch caused by uncertainties such as renewable energy in active distribution network, a day-ahead optimal dispatch strategy for active distribution network based on improved deep reinforcement learning is proposed. First, the day-ahead optimal dispatch problem for the active distribution network is modeled as a multistage stochastic programming model. Multistage models attempt to capture the dynamics of unfolding uncertainties over time, so that the interaction between decision making and uncertainty unfolding is represented more accurately and realistically, and the decision can be adjusted dynamically and adaptively. Second, with the help of deep neural network to approximate the power flow model of the active distribution network in a data-driven manner, an improved deep reinforcement learning algorithm is proposed to solve the corresponding multistage stochastic programming problem. The proposed improved deep reinforcement learning algorithm effectively solves the problem that trial-and-error information acquisition methods are difficult to apply to high-cost power systems. Finally, the effectiveness of the proposed day-ahead optimization dispatch strategy for active distribution network based on improved deep reinforcement learning is verified by a modified IEEE33 case.

关键词： Uncertainty Optimization Renewable energy sources Reinforcement learning Heuristic algorithms Adaptation models Active distribution networks Active distribution network multistage stochastic programming optimal dispatch data driven deep learning deep reinforcement learning

来源：评论

学校读者我要写书评

暂无评论

Active Participation of Air Conditioners in power system Frequency control Considering Users' Thermal Comfort

引用

ENERGIES 2015年第10期8卷 10818-10841页

作者： Zhang, Rongxiang Chu, Xiaodong Zhang, Wen Liu, Yutian Shandong Univ Minist Educ Key Lab Power Syst Intelligent Dispatch & Control Jinan 250061 Peoples R China

Air conditioners have great potential to participate in power system frequency control. This paper proposes a control strategy to facilitate the active participation of air conditioners. For each air conditioner, a decentralized control law is designed to adjust its temperature set point in response to the system frequency deviation. The decentralized control law accounts for the user's thermal comfort that is evaluated by a fuzzy algorithm. The aggregation of air conditioners' response is conducted by using the Monte Carlo simulation method. A structure preserving model is applied to the multi-bus power system, in which air conditioners are aggregated at certain load buses. An inner-outer iteration scheme is adopted to solve power system dynamics. An experiment is conducted on a test air conditioner to examine the performance of the proposed decentralized control law. Simulation results on a test power system verify the effectiveness of the proposed strategy for air conditioners participating in frequency control.

关键词： power system frequency control air conditioner thermal comfort fuzzy mathematics

来源：评论

学校读者我要写书评

暂无评论

Low-Voltage Ride-Through Remote Testing Method for Offshore Wind Turbines

引用

IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2020年第6期69卷 2905-2913页

作者： Jiang, Zimin Liu, Yutian Shandong Univ Minist Educ Key Lab Power Syst Intelligent Dispatch & Control Jinan 250061 Peoples R China

Grid-connected wind turbines (WTs) are required to have low-voltage ride-through (LVRT) capability. On-site LVRT test is a convincing certificating method. To tackle the limited accessibility and harsh conditions of on-site test for offshore WTs, this paper proposes a remote testing method, which places the testing device on shore to produce the specified fault voltages through a subsea cable to the WT. For further eliminating the effects of introduced cable on LVRT test, a stepwise voltage sag generation strategy is applied to suppress the overvoltage and maintain required voltage sags. First, the LVRT testing requirements and voltage sag specification need to be considered in a practical test are introduced. The stepwise generation strategy and its implementation procedure based on the designed testing device are presented. Second, the effects of submarine cable on the WT- side voltage are analyzed under different generation stages of voltage sags. Next, the testing device's impedance configuration method, based on the derived residual voltage expression, is given to generate the required steady-state voltage sags. Finally, simulation results indicate that with the proposed method, the effects of cable can be eliminated and the required grid faults can be emulated for remote LVRT test.

关键词： Low-voltage ride-through (LVRT) offshore wind turbine (WT) remote test voltage sag wind power

来源：评论

学校读者我要写书评

暂无评论

Global Synchronous Pulse Width Modulation of Distributed Inverters

引用

IEEE TRANSACTIONS ON power ELECTRONICS 2016年第9期31卷 6237-6253页

作者： Xu, Tao Gao, Feng Shandong Univ Minist Educ Key Lab Power Syst Intelligent Dispatch & Control Jinan 250061 Peoples R China

Traditionally, the parallel-connected multileg inverter could assume the interleaved pulse width modulation (PWM) to attenuate the high-frequency harmonics by using a single controller to generate the corresponding interleaved switching sequences. However, the interleaved PWM cannot be employed in multiple distributed independent inverters installed at different locations with their own controllers because the multiple independent controllers cannot work synchronously and the operational conditions are different among the distributed inverters. The summed current harmonics of multiple distributed inverters could vary at the point of common coupling (PCC) and worsen the power quality of consumers. This paper, therefore, proposes a global synchronous PWM method for the distributed inverters to attenuate the high-frequency current harmonics at PCC. The optimal interleaved switching angles among the distributed inverters are calculated by fully considering line impedances, modulation indexes, switching frequencies, the number of distributed inverters, etc. Particle swarm optimization method is assumed to find the optimal solution. Then, the low-frequency synchronization operation will synchronize the multiple PWM switching sequences in the wanted variation range. Experimental results are presented to prove the validity of this method.

关键词： Current harmonics distributed inverters global modulation synchronous pulse width modulation

来源：评论

学校读者我要写书评

暂无评论

Risk-Based Reserve Scheduling for Active Distribution Networks Based on an Improved Proximal Policy Optimization Algorithm

引用

IEEE ACCESS 2023年 11卷 15211-15228页

作者： Li, Xiaoyu Han, Xueshan Yang, Ming Shandong Univ Key Lab Power Syst Intelligent Dispatch & Control Minist Educ Jinan 250061 Peoples R China

Achieving the coordinated optimization of tie-line reserve and energy storage on two timescales is a key issue in reserve scheduling for active distribution networks. To effectively manage the uncertainty related to renewable energy, we propose risk-based reserve scheduling for active distribution networks based on an improved proximal policy optimization algorithm. The reserve scheduling for active distribution networks is constructed as a two-scale multistage stochastic programming model, in which intraday real-time operation is constructed as a multi-stage stochastic programming model. With the help of more accurate and realistic intraday operation scenario simulation, the energy storage can be fully utilized to improve the system's ability to climb and peak, reduce the reserve pressure of the main network, and achieve the purpose of improving the flexibility of system operation. An improved proximal policy optimization algorithm is proposed to solve optimization problems in a model-free manner while effectively handling conditional value-at-risk constraints. The effectiveness of the proposed risk-based reserve scheduling for active distribution networks based on an improved proximal policy optimization algorithm is verified by a modified IEEE33 case.

关键词： Optimization Renewable energy sources Reactive power Costs power systems Active distribution networks Deep learning Reinforcement learning Active distribution network multistage stochastic programming conditional value-at-risk reserve scheduling deep reinforcement learning

来源：评论

学校读者我要写书评

暂无评论

A new method for standing phase angle reduction in system restoration by incorporating load pickup as a control means

引用

INTERNATIONAL JOURNAL OF ELECTRICAL power & ENERGY systemS 2013年第1期53卷 664-674页

作者： Ye, Hua Liu, Yutian Shandong Univ Key Lab Power Syst Intelligent Dispatch & Control Minist Educ Jinan 250061 Peoples R China

In restoring a power system after a major disturbance, system operators often encounter an excessive standing phase angle difference (SPA) between two buses of a circuit breaker when a transmission line is energized and results in a loop closure. Under such a condition, there is high risk of damage to nearby generators and other equipments for the breaker/loop closure operation. Since the SPA value is a function of the restoring system topology, load and generation injections, the SPA reduction becomes an important problem in system restoration. Presently, generation rescheduling is adopted as a primary control means and load shedding is used as the final resort to reduce the SPA. In fact, there remains a lot of unserved load in the system throughout the restoration process. Since the unserved load that can help reduce the SPA is not picked up and selected as a control means, the existing control strategy for SPA reduction is not optimal for a system under restorative state. In this paper, a new method that incorporates load pickup as a control means is proposed to address the SPA reduction problem. Firstly, a general principle for SPA reduction is established, i.e., a smaller SPA can be achieved by lowering the total active power flow transmitted from the sending-end to the receiving-end subsystem. Based on which, the pickup of load in the sending-end subsystem and the increased active power generation in the receiving-end subsystem are combined as control means. Then a mixed integer nonlinear programming (MINLP) algorithm and an alternative two-stage decoupled (TSD) algorithm are proposed to develop specific control strategies. The algorithms can help restore some unserved load during the process of SPA reduction and, thus, are more effective in achieving the goal of power system restoration. Simulation results on the New England test system demonstrate the effectiveness of the proposed algorithms. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： power system restoration Load restoration Standing phase angle Transmission loop closure Load pickup Generation rescheduling

来源：评论

学校读者我要写书评

暂无评论

A Family of Neutral-Point-Clamped Circuits of Single-Phase PV Inverters: Generalized Principle and Implementation

引用

IEEE TRANSACTIONS ON power ELECTRONICS 2017年第6期32卷 4307-4319页

作者： Zhou, Liwei Gao, Feng Xu, Tao Shandong Univ Minist Educ Key Lab Power Syst Intelligent Dispatch & Control Jinan 250061 Peoples R China

The common-mode leakage current should be carefully considered when designing a transformer-less photovoltaic (PV) inverter since the leakage current can cause the output current distortion and increase the operational risk. The unipolar sinusoidal pulse width modulation of the traditional H-bridge inverter can produce the superior output performance but will cause a high-frequency fluctuated common-mode voltage and consequently the nonnegligible leakage current. To attenuate the fluctuation phenomena of common-mode voltage, few neutral-point-clamped (NPC) circuits have been designed to clamp the neutral-point voltage andmaintain the common-mode voltage constant. This paper analyzes the equivalent common-mode circuit of single-phase inverters and proposes a generalized design principle of multiterminal NPC circuits, whose unidirectional and bidirectional variations are fully analyzed. Subsequently, two types of single-phase PV inverters with the NPC circuits are proposed. Also, the operational losses and component counts are compared between the proposed topologies and the traditionalNPC inverters. The experimental results verified the theoretical findings.

关键词： Common-mode voltage neutral-point-clamped (NPC) circuit photovoltaic (PV) inverter single-phase inverter

来源：评论

学校读者我要写书评

暂无评论

A Three-Phase Adaptive Reclosure Technology for Distribution Feeders Based on Parameter Identification

引用

IEEE TRANSACTIONS ON power DELIVERY 2019年第6期34卷 2173-2181页

作者： Zhu, Ke Lv, Rundong Shandong Univ Key Lab Power Syst Intelligent Dispatch & Control Minist Educ Jinan 250061 Peoples R China

A scheme is proposed to improve the decreasing success rate of reclosing in a non-effectively grounded system with a wide application of cables. An inverter source is momentarily connected to the low-voltage side of a service transformer by controlled thyristors to apply a transient high voltage to the de-energized feeder before reclosing. Based on the idea of parameter identification, the internal structure of the de-energized feeder is investigated according to the frequency characteristics of the reference parameters to determine whether the feeder still experiences the fault. The influence of the firing angle on the strength of the frequency components in the transient waveforms is analyzed to determine its range for accurate measurement of feeder harmonic impedance. A sensitivity analysis on the fault property detection criterion is conducted, and the selection of the inverter source power impacted by the firing angle is provided. The results of the theoretical analysis, computer simulation, and lab experiments confirmed the effectiveness of the proposed scheme.

关键词： Adaptive reclosure de-energized feeder transient fault thyristor

来源：评论

学校读者我要写书评

暂无评论

Adaptive Quasi-power Differential Protection Scheme for Active Distribution Networks

引用

IEEE TRANSACTIONS ON SMART GRID 2024年第1期15卷 324-339页

作者： Yuan, Tong Gao, Houlei Peng, Fang Li, Lin Zhang, Yunchi Zhao, Qian Shandong Univ Key Lab Power Syst Intelligent Dispatch & Control Minist Educ Jinan 250061 Peoples R China

With the massive integration of distributed generations (DGs), distribution networks gradually become more active and flexible. Conventional overcurrent protection is difficult to adapt to such active distribution networks (ADNs). Current differential protection (CDP) is a good choice for solving this issue, but the multi-branch structure of ADNs especially the unmeasured T-connected load branch affects the protection's sensitivity. Therefore, the paper proposes a quasi-power differential protection (QDP) scheme based on Tellegen's theorem. First, the feasibility of applying Tellegen's theorem to ADNs was analyzed. On this basis, reasonable protection criteria were designed for different scenarios of ADNs. Then, an adaptive protection scheme was established, which can automatically adjust the criteria depending on the presence of T-connected branches within the protected section. Finally, extensive simulations were carried out in an ADN model using PSCAD/EMTDC software. The simulation results demonstrate that the proposed protection scheme has excellent adaptability to network topologies, fault types, fault resistances, and network structures of ADNs.

关键词： Circuit faults Distribution networks Voltage power transmission lines Sensitivity Manganese Equivalent circuits Active distribution network Tellegen's theorem unmeasured T-connected load branch differential protection

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：