An Uplink Power Control Scheme in CDMA Mobile Communication System

A brief introduction of principles and algorithm realization of uplink power control in CDMA mobile communication system based on IS 95 are given, and then the blocking probability and Erlang capacity under the condition of perfect and imperfect uplink power control are presented and analyzed. Finally the uplink power control algorithms are simulated, and the optimum uplink power control algorithm that maximizes system Erlang capacity is acquired.

Accomplishing Consummate Throughput with Delay and Power Control in MANET

Mobile Ad Hoc Network is a self-configuring, autonomous, infrastructure less network of movable nodes which will be automatically connected by wireless connection with no access point. The nodes are free to move anywhere in the set of connections and the topology of MANET remains unpredictable. The major complexity with the available two hop relay protocols in MANET environment is to achieve the optimized throughput with reduced packet delivery delay. A generalized collection based two-hop relay and redundancy of the packet is used to attain the reduced delay. The complex process of packet delivery in MANET utilizes Routine Response Control and Modified Markov chain model. Tuning carefully the parameters, the transmission range, the packet redundancy and the group size help to achieve the optimized throughput with the reduced packet delivery delay. Transmission power of a node is controlled which helps in achieving the optimized throughput and reduced delay.

基于MSC1210的电源控制模块的设计

介绍了基于MSC1210单片机设计的一个电源控制模块,它通过RS-485总线实现与上位机的通信,来控制电源的开关、调节和状态获取等,实践表明,该模块具有较高的可靠性、实时性和适应性。

Reliability and sensitivity analysis of loop-designed security and stability control system in interconnected power systems

Security and stability control system(SSCS)in power systems involves collecting information and sending the decision from/to control stations at different layers;the tree structure of the SSCS requires more levels.Failure of a station or channel can cause all the execution stations(EXs)to be out of control.The randomness of the controllable capacity of the EXs increases the difficulty of the reliability evaluation of the SSCS.In this study,the loop designed SSCS and reliability analysis are examined for the interconnected systems.The uncertainty analysis of the controllable capacity based on the evidence theory for the SSCS is proposed.The bidirectional and loop channels are introduced to reduce the layers and stations of the existing SSCS with tree configuration.The reliability evaluation and sensitivity analysis are proposed to quantify the controllability and vulnerable components for the SSCS in different configurations.By aiming at the randomness of the controllable capacity of the EXs,the uncertainty analysis of the controllable capacity of the SSCS based on the evidence theory is proposed to quantify the probability of the SSCS for balancing the active power deficiency of the grid.

Capacity analysis of based-regular-topologies cognitive wireless mesh networks with power control

Capacity analysis is a fundamental and essential work for evaluating the performance of cognitive wireless mesh network （CWMN） which is considered a promising option for the future network. Power control is an efficient way to avoid interference and improve capacity of wireless mesh networks. In this paper, a quantitative result of the per-node average throughput capacity of CWMN with power control is deduced for the first time, which is much helpful for understanding the limitations of CWMN. Firstly, under the large-scale channel fading model and protocol interference model, a closed-form expression for the maximum channel capacity of each node with power control is presented, under the constraint that the interference tolerated by the primary users （PUs） does not exceed a threshold. And then, with the deduced channel capacity result, the per-node average throughput capacity of CWMN is derived based on two regular topologies, i.e. square topology and triangle topology. The simulation results indicate that the capacity is effectively improved with power control, and affected by topology, tolerated interference threshold, the number of cognitive users （CUs） and primary users （PUs）.

H-M Bearing Capacity of A Modified Suction Caisson Determined by Using Load-/Displacement-Controlled Methods

This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs （modified suction caissons） in the saturated marine fine sand. The lateral loads were applied under load- and displacement-controlled methods at the loading eccentricity ratios of 1.5, 2.0 and 2.5. Results show that, in the displacement-controlled test, the deflection-softening behavior of load-deflection curves for MSCs was observed, and the softening degree of the load-deflection response increased with the increasing external skirt length or the decreasing loading eccentricity. It was also found that the rotation center of the MSC at failure determined by the load-controlled method is slightly lower than that by the displacement-controlled method. The calculated MSC capacity based on the rotation center position in serviceability limit state is relatively conservative, compared with the calculated capacity based on the rotation center position in the ultimate limit state. In the limit state, the passive earth pressures opposite the loading direction under load- and displacement-controlled methods decrease by 46% and 74% corresponding to peak values, respectively; however, the passive earth pressures in the loading direction at failure only decrease by approximately 3% and 7%, compared with their peak values.

Dispersed Wind Power Planning Method Considering Network Loss Correction with Cold Weather

In order to play a positive role of decentralised wind power on-grid for voltage stability improvement and loss reduction of distribution network,a multi-objective two-stage decentralised wind power planning method is proposed in the paper,which takes into account the network loss correction for the extreme cold region.Firstly,an electro-thermal model is introduced to reflect the effect of temperature on conductor resistance and to correct the results of active network loss calculation;secondly,a two-stage multi-objective two-stage decentralised wind power siting and capacity allocation and reactive voltage optimisation control model is constructed to take account of the network loss correction,and the multi-objective multi-planning model is established in the first stage to consider the whole-life cycle investment cost of WTGs,the system operating cost and the voltage quality of power supply,and the multi-objective planning model is established in the second stage.planning model,and the second stage further develops the reactive voltage control strategy of WTGs on this basis,and obtains the distribution network loss reduction method based on WTG siting and capacity allocation and reactive power control strategy.Finally,the optimal configuration scheme is solved by the manta ray foraging optimisation(MRFO)algorithm,and the loss of each branch line and bus loss of the distribution network before and after the adoption of this loss reduction method is calculated by taking the IEEE33 distribution system as an example,which verifies the practicability and validity of the proposed method,and provides a reference introduction for decision-making for the distributed energy planning of the distribution network.

Evaluation of optimal UPFC allocation for improving transmission capacity

A unified power flow controller(UPFC)combines the advantages of various flexible alternating current transmission system(FACTS)devices into a powerful format.Using a 500 kV power grid,this study evaluates the selection and use of a UPFC to improve transmission capacity.The"UPFC unit capacity control proportionality coefficient"is introduced to quantify the control effect of the UPFC,and an optimal calculation method for the UPFC capacity is presented.Following the proposal of a UPFC site selection process,the data of an existing power grid is used to conduct simulations.The simulation results show that the UPFC has a strong ability to improve transmission capacity,and its use is greatly advantageous.Additionally,by applying the proposed selection method,the control effect and economic benefits of the UPFC can be comprehensively considered during project site selection.These findings have a guiding significance for UPFC site selection in ultra-high voltage power grids.

ERGODIC CAPACITY ANALYSIS FOR SIMO COGNITIVE FADING CHANNEL IN SPECTRUM SHARING ENVIRONMENT

In this paper,we consider the spectrum sharing Cognitive Radio(CR) system,wherein Single-Input Multi-Output(SIMO) cognitive fading channel is assumed.Subject to the average in-terference constraint of primary user,the ergodic capacity of cognitive user involving joint beamforming and power control is analyzed.We derive the optimal joint beamforming and power control strategy and deduce the general integral expression for ergodic capacity.Furthermore,under different channel fadings including Raleigh fading,Nakagami-m fading and Lognormal shadowing fading,the specific expressions of ergodic capacity for SIMO cognitive channel are exhibited.Most of the expressions are presented in closed-form or with some special integral functions.Large amount of simulations are conducted to corroborate our theoretical results.

光伏微网储能系统用电峰谷差自适应控制技术

光伏微网储能系统(PMESS)用电峰谷差的增大会导致电网负荷波动增大,影响电网的稳定性。为了有效降低电网的峰谷差,提出一种光伏微网储能系统用电峰谷差自适应控制技术。通过估计光伏微网发电系统的负荷,计算光伏微网储能系统的充电功率和电量,并根据该计算结果计算光伏微网储能系统的额定容量。设置用电峰谷差自适应控制约束条件,并结合二轮迭代的方式实现光伏微网储能系统用电峰谷差自适应控制。实验结果表明,所提技术可以准确估计光伏微网发电系统负荷,并将用电峰谷差控制在200 kW左右,同时,可以有效提升光伏微网储能系统的有功功率,具有良好的实际应用效果。

计及灵活经济环保运行的火电-飞轮储能系统容量配置与调频参数协同优化

提出了一种计及灵活经济环保运行的火储系统容量配置与调频参数协同优化方法。首先,设计了一种基于低通滤波自动分配火储功率和考虑储能荷电状态自恢复的火储联合一次调频协调控制策略;综合考虑系统调频性能、投入运行成本、污染物排放等,建立了火储容量配置与调频参数协同优化模型,并给出了基于粒子群算法的求解方法。最后,以某火储系统为例进行仿真验证。结果表明:协调控制策略和协同优化方法具有有效性。

提升末端区域电网供电能力的调控方案及稳控策略研究

针对内蒙古某末端区域电网供电能力受同塔双回线路N-2故障及母线故障制约问题,开展安全稳定控制系统(以下简称稳控系统)控制策略研究。首先,基于对典型故障后末端区域电网稳定特性的仿真计算与分析,结合新能源出力、火电机组开机等对切负荷定值的影响,制订预控方案与稳控系统相结合的综合调度控制方案;然后,分析电解铝行业整流变压器负荷转移特性,提出可优先实切负荷量计算方法和适用于末端电网的分档阶梯切负荷原则,对末端区域电网稳控系统的控制策略进行优化。

计及多时间尺度的梯级水-风-光互补基地储能容量优化配置

含高比例风光发电的清洁能源基地是碳中和的有效途径,但风光发电出力的随机性和波动性严重影响电网的安全稳定运行。为此,提出了一种计及水-风-光互补和电池分组运行的多时间尺度嵌套清洁能源基地储能容量优化配置方法。在含梯级水-风-光的清洁能源基地中加入电池组,并研究其三分组充放电控制运行策略。构建计及水-风-光互补的多时间尺度嵌套双层储能容量优化配置模型,其中内层利用水-风-光互补性,平抑大时间尺度的风光出力大波动,外层计及衰减度对储能进行优化,以平抑小时间尺度的风光出力小波动。通过算例分析表明所提模型能充分利用灵活调控的水电与快速响应电池的互补优势有效平抑清洁能源基地功率波动,并对比验证了所提三电池组分组控制策略在节约成本以及减缓损耗方面的有效性。

能源汇集系统中多模式接入储能的协调控制及优化设计方法

随着能源汇集系统中新能源设备接入比例不断增加,光伏、负荷的不确定性将带来电能质量问题,给电网稳定运行带来挑战,为解决此问题,通过储能接入实现系统电压和功率的补偿控制。首先,分析电网电压与功率之间的耦合影响机理;然后,利用串联型接入储能和并联型接入储能针对电网中的电压波动与功率波动进行协调补偿;最后,基于储能的协调控制对不同接入模式的储能传输容量进行优化设计,满足能源汇集系统补偿需求,保障系统稳定运行。通过仿真算例验证了所提协调控制及优化设计方法的有效性,能够降低储能设计总量,具有实际应用价值。

基于改进类电磁机制算法的UPFC多目标优化配置

统一潮流控制器(UPFC)能在不改变线路拓扑结构的条件下有效地改善电力系统潮流,从而提高输电能力与电压稳定性。针对系统可用输电能力、电压偏差和L指标等目标,建立了UPFC的多目标优化配置模型,采用结合差分进化算法(DE)的改进差分类电磁机制算法(DEEM)对所建模型进行求解,通过对算法中粒子的带电量、合力计算方式进行改进,同时添加自适应因子,进一步平衡算法的全局搜索与局部搜索能力。配置后的结果表明UPFC对增强系统输电能力、电压质量及电压稳定性的性能均有提高,且改进算法寻优效率的提升也得到了验证。

高比例光伏接入的分布式储能容量自适应协调控制方法

光伏发电具有一定的波动性和不确定性,天气、季节等因素会导致光伏功率的变化,需要储能系统实时跟踪、预测和调整以保持供需平衡,但波动性和不确定性增加了控制的复杂性。为此,提出一种新的分布式储能容量自适应协调控制方法。计算接入高比例光伏电能后储能无功损耗,设置功率约束条件,确保功率的稳定性。基于此,以电压条件最优、接入负荷和净功率最低、高比例光伏接入处的功率可调节范围最优为调控目标,实现高比例光伏接入的分布式储能容量自适应协调控制。实验数据证明,所提方法在控制效果方面具有显著优势,能够实现高效的分布式储能控制,并确保光伏的高效出力。

基于供电能力的行车动态卡控方法

[目的]在城市轨道交通线路中,牵引供电设施支持列车运行的数量具有上限。当前续列车故障或者繁忙线路列车追踪密度过高时,可能导致供电臂负荷电流过大而引起电力开关跳闸,从而严重影响运营。传统的ATS(列车自动监控)系统无法智能化掌握供电系统的实时运行情况,需研究供电能力和行车的关系以实现行车动态卡控。[方法]基于供电臂供电能力分析以及列车运行曲线,提出一种行车动态卡控方法。通过对信号、供电、车辆和轨道等多专业数据进行融合分析,并结合大数据电流曲线预测模型,实现对供电负载能力的动态监测与预测。将预测的电流曲线与列车ATO(列车自动运行)运行曲线有机结合,实时调整进入当前供电臂运行的列车数,实现动态卡控列车运行。该方法在深圳地铁16号线上进行了实例验证。[结果及结论]基于供电能力的行车卡控方法通过预测列车所需取流动态调整列车运行,可有效避免因行车导致过负荷引起的供电系统跳闸故障,在保证运营效率的同时,提高了线路运营的安全性。

基于短路比指标的新能源并网容量极限计算

针对新能源并网系统抗干扰能力弱且稳定性较差等问题,在短路比指标的基础上,提出了一种适用于新能源发电机组和交流电网之间的系统容量计算方法。通过推广电网系统的短路比指标,利用电力电子多馈入系统灵敏度计算方法,实现系统容量受到小干扰因素影响时变化情况的精准评估,并且获取系统在达到临界状态时的具体条件,从而实现新能源并网系统中容量极限的精确计算和分析。仿真结果表明,与经典容量极限计算方法相比,基于短路比指标的容量极限算法具有更高的稳定性及抗干扰能力。

面向光伏电站的电池储能系统运行策略与容量配置优化

储能系统能够有效平抑光伏发电出力的波动性,为了最大化光伏电站与储能系统联合运行的收益,研究了储能电站的运行控制策略和容量配置优化。依托甘肃某100 MW光伏项目储能电站建立运行策略分析模型,在电化学储能参与不同电力调频辅助服务的多种场景下,分析了光储联合运行的经济性。结果显示,储能电站同时参与价格套利服务和调频服务市场可显著提升收益;其次,基于最佳运行策略,对储能电站额定功率和最大连续储能时长进行敏感性分析,采用NSGA-Ⅱ算法及TOPSIS算法,以储能电站年运行成本最低为目标建立了储能容量配置优化模型;最后,通过计算得出最佳配置功率及最大连续储能时长分别为30.99 MW和4.52 h,此时日均收益为23.6万元,初始投资成本为14 503.3万元,投资回收期为4.56 a。

某大型数据中心冷源扩容改造研究

论文研究了某大型数据中心基于业务负载增加带来的冷源扩容改造,通过实测和比较法对扩容冷源的适配性进行阐述,分析了冷源扩容带来的电力扩容、群控匹配等问题,获取了大型离心式冷水机组冷源扩容的系统匹配性,为类似工程的实施提供了依据。