Enhancing Autonomy Capability in Regional Power Grids:A Strategic Planning Approach with Multiple Autonomous Evaluation Indexes

After the integration of large-scale DistributedGeneration(DG)into the distribution network,the randomness and volatility of its output result in a reduction of spatiotemporal alignment between power generation and demand in the distribution network,exacerbating the phenomenon of wind and solar power wastage.As a novel power system model,the fundamental concept of Regional Autonomous Power Grids(RAPGs)is to achieve localized management and energy autonomy,thereby facilitating the effective consumption of DGs.Therefore,this paper proposes a distributed resource planning strategy that enhances the autonomy capabilities of regional power grids by considering multiple evaluation indexes for autonomy.First,a regional Energy Storage(ES)configuration strategy is proposed.This strategy can select a suitable reference value for the upper limit of ES configuration based on the regional load andDGoutput to maximize the elimination of source load deviations in the region as the upper limit constraint of ES capacity.Then,a control strategy for regional ES is proposed,the charging and discharging reference line of ES is set,and multiple autonomy and economic indexes are used as objective functions to select different proportions of ES to control the distributed resources of the regional power grid and establish evaluation indexes of the internal regional generation and load power ratio,the proportion of power supply matching hours,new energy consumption rate and tie line power imbalance outside the region to evaluate changes in the regional autonomy capabilities.The final simulation results showthat in the real regional grid example,the planning method in the planning year in the region of the overall power supply matching hour ratio and new energy consumption rate increased by 3.9%and 4.8%on average,and the power imbalance of the tie line decreased by 7.8%on average.The proposed planning approach enables the maximization of regional autonomy while effectively smoothing the fluctuation of power exchange between the regional grid and the higher-level grid.This presents a rational and effective planning solution for the regional grid,facilitating the coordinated development between the region and the distribution network.

Review of trans-Mediterranean power grid interconnection:a regional roadmap towards energy sector decarbonization

Climate change is becoming an important issue in all fields of infrastructure development.Electricity plays a core role in the decarbonized energy system’s path to a regional zero-emission pattern.A well-built trans-Mediterranean backbone grid can hedge the profound evolution of regional power generation,transmission,and consumption.To date,only Turkey and the Maghreb countries(i.e.,Morocco,Algeria,and Tunisia)are connected with the Continental European Synchronous Area.Other south-and east-shore countries have insufficient interconnection infrastructures and synchronization difficulties that have proven to be major hurdles to the implementation of large-scale solar and wind projects and achievement of climate goals.This study analyzes the current trans-boundary grid interconnections and power and carbon emission portfolios in the Mediterranean region.To align with the recently launched new climate target‘Fit for 55’program and the accelerated large-scale renewables target,a holistic review of projected trans-Mediterranean grids and their market,technical,and financial obstacles of implementation was conducted.For south-and east-shore countries,major legal and regulatory barriers encompassing non-liberalized market structure,regulation gaps of taxation and transmission tariffs,and the private sector’s access rights need to be removed.Enhancement of domestic grids,substations,and harmonized grid codes and frequency,voltage,and communication technology standards among all trans-Mediterranean countries are physical prerequisites for implementing the Trans-Mediterranean Electricity Market.In addition,the mobilization of capital instruments along with private and international investments is indispensable for the realization of supranational transmission projects.As the final section of the decarbonization roadmap,the development of electric appliances,equipment,and vehicles with higher efficiency is inevitable in the decarbonized building,transportation,and industry sectors.

Research on Safety and Stability of Regional Power Grids to the Year 2020

The safety and stability study on Northeast, North, East, Northwest and Central China power grids had been carried out, which provided technical supports to planning design of regional power grids. By analyzing safety and stability under severe faults in regional power grids, revealed weaknesses on power grid configurations and measures for preventing from loss of stability were presented. In comparison of various schemes of power system safety and stability among parts of power grids, more than two recommended schemes can be chosen as reference in planning design for regional power grids. Considering the safety and stability control measures necessary for each power grids, it is believed the trunk networks of all power grids can fulfill the third criteria of Guideline for Power System Safety and Stability, while the weakness and predominated hydropower may deteriorate safety and stability of power grids. The power grid shall be regulated in line with the variation of boundary conditions.

An Outlook on Northwest Power Grid Development

In this paper the basic situation of the Northwest Region in China is introduced, the necessity for the Northwest Power Grid to develop 750 kV transmission line is analyzed, and the target for the power grid construction till 2010 as well as the planning for sending power from west to east and interconnection with adjacent grids are described.

Problems of Planning for Power Industry in China

On the basis of summing up the development of electric power industry in the 10th Five-Year Plan period, the idea of electric power development planning from 2006 to 2020 is presented. The authors analyzed ten main problems that existed in electric development during the 10th Five-Year Plan period, forecasted the electricity generation from 2006 to 2020, put forward the development strategy of power industry, discussed the component and development program of hydropower, thermal power, nuclear power, natural gas power and renewable power, outlined the present situations of six regional power grids, power transmission from western to eastern regions, UHV AC/DC power transmission and nationwide power grid interconnections, and finally gave out seven suggestions about electric power development in the future.

分布式优化在互联电网中的应用分析及展望

在新能源随机性与波动性的影响下,互联电网能量与灵活性的跨区域互济重要性凸显,有效的分布式优化算法是不可或缺的技术支撑。为了在互联电网不同运行层级的重要场景中选择适宜的算法,文中归纳了分布式优化建模和求解的一般原理,并提出将现有分布式算法分为原始可行方向、对偶可行方向、原对偶、切平面、列生成和多参数法6类。针对互联电网的多区域输电网协同调度、输配协同优化调度以及配电网分布式资源协同调度不同运行层级这3个重要场景,阐明了采用分布式优化的必要性,总结了统一的变量/约束耦合问题的典型建模及变换关系,并分析了6类算法在各场景的实施情况和应用优缺点。从物理场景、数学模型以及算法整体角度分析分布式优化在互联电网3个重要场景应用存在的问题,并给出了不同场景的算法选取建议。结合配电网运行新场景、数学建模新问题、算法设计新技术,展望了未来互联电网应用分布式优化的方向。

区域互联下不对称交流电网运行控制系统设计

电力系统内部的交流电在产生不对称故障之后,会直接导致换流站母线电压不平衡,系统内部出现的负序分量和零序分量会影响系统交流和直流谐波分布,进而影响电网的正常运行。为了进一步实现不对称交流电网的控制,设计了一种控制系统。系统硬件设计了锁相环控制器、电流环控制器、DSP控制器,锁相环控制器由相位鉴别、环路滤波和压控振荡三部分组成一个闭环。针对区域互联状况进行分析,确定谐波电压和谐波电流的传递规律,建立谐波分析程序和控制程序,通过矢量计算,对不对称交流电网电流进行运行控制。实验结果表明,所设计系统能够有效解决运行过程的输入量和输出量不均衡的问题,降低叠加放大状况,控制后电流和电压幅值波动为0,有效防止出现谐波不稳定现象。

区域互联多电压等级直流电网运行控制系统

为了提高直流电网运行控制能力,设计了区域互联多电压等级直流电网运行控制系统。分析电网的单级接线和双极接线的运行状态,通过搭建换流器和逆变器完成系统硬件设计。在软件设计中,设定功率调制功能、定电流控制功能、定电压控制功能,通过确定两个地区间的交流功率变化实现功率调节,根据定电流控制原理得到传感器输出数值,以此实现定电流控制,结合直流输入功率实现定电压控制,达到直流电网运行控制的目标。实验结果表明,设计系统的控制结果与标准要求吻合度在95%以上,具有极强的控制能力。

区域互联电网电能量与备用辅助服务联合优化模型研究

电能量市场与备用辅助服务市场联合优化能够在满足系统安全运行约束的前提下实现经济效益最优,是国外典型电力现货市场运行的最佳实践。在我国现行的"分层分区"电力调度管理体制下,电网安全与备用容量管理在区域、省级调度中心之间各有权责,存在全系统及各分区的备用需求容量配置、分区间备用的有效调度等问题,不能直接照搬国外的电能量与备用联合出清机制与模型。分析了我国区域互联电网条件下的电能量与备用辅助服务联合优化市场模式,提出了计及多因素的系统及各分区的备用需求容量设置方法,分别构建了单区域、多区域互联两种情形下的联合优化出清数学模型。最后,基于三区域IEEE-RTS96系统进行算例分析,验证了所提分区备用需求容量配置方法及区域电网联合优化出清数学模型可充分考虑区域间运行约束对预留备用容量有效性的影响,从而极大提升系统运行的可靠性。

区域电网内弱联机群摆动对互联系统功角稳定性的影响

基于三机等值系统,从区域内部发电机群摆动对等值电势的影响入手,探讨研究大互联电网暂态稳定新特征。分析表明,扰动后区域内部机群会相互摆动,导致等效电势幅值变动,使互联系统功率特性产生变化,从而影响到系统暂态稳定能力。其中,当区域内功角超前机群受扰严重时,互联系统更容易发生功角稳定问题。因此在研究大互联系统暂态稳定性问题时,并不能简单地用故障期间冲击能量衡量系统暂态稳定受扰严重程度,还需分析区域机群相互摆动给系统暂态稳定所带来的影响。

促进跨区新能源消纳的直流联络线功率优化模型及分析

提出了一种考虑直流联络线功率阶梯化运行、送端电网与多个受端电网跨区协调的常规能源与新能源联合优化的发电计划模型。建立了直流联络线功率阶梯化运行的数学模型,该模型满足直流功率调整的各项特性要求,包括直流功率阶梯化、相邻时段不可反向调整、稳定运行持续时间、日交换电量不变等约束,既充分发挥了直流联络线可灵活调节的特点,又避免了高压直流换流设备的频繁转换,提高了直流联络线计划的可执行性。同时,该模型可考虑多个跨区互联电网间的多条输电通道,以及送受端电网间的系统负荷互补性和新能源接纳能力,实现了送受端电网间的协调调度,促进新能源在更大空间范围内消纳。基于国内某跨区互联电网的实际数据,验证了所提模型的有效性。

区域电网互联对广东电网暂态稳定性的影响分析

广东电网是南方五省区电网中最大的受端电网,通过交直流混合联网接受区外电力,但交流系统故障和直流系统故障严重威胁其安全稳定运行。电网交流互联对原电网的暂态稳定特性有很大影响,文中以南方电网中长期规划提出的电力流方案和主网架方案为基础,通过仿真研究了3种区域电网互联方案对广东电网暂态稳定性的影响。结果表明受端电网交流互联,而送受端电网异步运行的两广同步网方案能最大限度地提高广东电网的暂态稳定性。

特高压及500kV区域联网的仿真复现与比较

为给特高压电网小干扰、暂态电压、功角等的稳定计算和分析奠定基础,在区域电网公司能量管理系统(energy management system,EMS)和广域测量系统(wide area measurement system,WAMS)记录的国内某两大区域电网间2008年底先后进行的500 kV联网、特高压联网试验两次试验基础上,通过校核网络结构、调整电网有功和电压、优化扰动模拟方案等一系列调试、分析方法,成功将潮流、暂态过程波形调整至与实测值相符,复现出了两次联网试验的暂态过程,从而校核了联网系统静态和动态仿真模型及参数的正确性,为后期进行暂态稳定仿真与分析、小干扰稳定计算分析奠定了基础。

利用储能技术实现交流互联电网分区解耦控制的可行性研究

交流联网可能会带来互联电网的动态稳定性问题。通过对交流和直流2种联网方式的对比分析,提出利用储能技术实现交流互联电网分区解耦控制的思路,即通过储能装置消除2个交流互联的区域电网之间的相互影响,各区域电网只需按照本区域的电网特性进行稳定控制。

区域电网间联网试验暂态过程的仿真

2008年底国内某2大区域电网先后进行了500kV联网试验和特高压联网试验。为校核互联系统静态和动态仿真模型及参数的正确性、掌握互联电网动态特性,在区域电网公司能量管理系统(energy management system,EMS)和广域测量系统(wide area measurement system,WAMS)记录的试验数据基础上,运用电力系统分析综合程序对这2次试验进行了暂态过程仿真研究。基于调整好的稳态方式,通过分析、优化扰动模拟方案、不断修正和调整潮流、调节器参数等措施,使暂态仿真波形与实测波形吻合的较好,成功复现出试验暂态过程,获得了与电网动态特性相一致的仿真模型,为仿真研究互联电网其它内容奠定了基础。

电网暂态相继失稳风险评估及协调阻断方法研究

以跨区互联电网为背景,以阻断电网发生暂态相继失稳、降低发生大停电事故风险、减少系统失稳控制代价为目的,提出了一种基于多代理技术的电网暂态相继失稳协调阻断方法。该方法首先基于确定性和风险分析方法,搜索多种工况下电网发生严重故障导致系统功角失稳情况后在相继事件作用下可能发生的暂态相继失稳模式及其事故链。然后,基于EEAC分群理论对控制策略进行搜索,解决不同失稳模式下的控制策略冲突问题,利用EEAC量化分析工具对不同控制措施进行排序。最后,以系统总风险最小为目标对预防控制和紧急控制进行协调优化。仿真验证了该方法的可行性。

考虑联络线传输功率的双层分区多目标输电网规划

为提高区域电网联络线的输电能力,最大范围优化资源分配,建立考虑经济性、可靠性指标的基于电网分区的双层多目标输电网规划模型。上层规划模型对全网采用线路建设成本最小、联络线传输功率最大和最小切负荷量作为优化目标进行网络优化,搜索到的优化方案传递给下层规划模型。下层规划在此方案基础上,以最大负荷供应能力指标指导受端电网规划并突出其受电和负荷增长特性;得到的规划方案再次传递到上层模型,由此反复交替进行直至获取满意的优化方案。提出应用粗糙集理论优势类函数和劣势类函数评价各子目标备选方案的相对排序指标,得到综合评价值进行多目标优化方案选择。46和77节点系统算例验证了该模型和方法的有效性。

区域电网远端故障引发互联系统稳定破坏现象探究

针对仿真分析中发现区域电网远端故障引发互联系统稳定破坏的现象。基于四机两区域互联系统,研究了大区互联电力系统暂态稳定特性。指出系统的网络结构和运行方式均会影响系统暂态失稳表现形式。在定条件下,可能发生较小的故障冲击造成互联系统失去暂态稳定,而较大的故障冲击不会使得互联系统暂态失稳。研究结果有助于掌握大区互联系统暂态稳定特性及其可能发生的失稳形式,以加深对大区互联电力系统运行特性的理解,保证互联系统安全稳定运行。

区域电网2020年目标网架安全稳定研究

对东北、华北、华东、西北、华中的2020年目标网架进行了安全稳定研究,为各区域电网的目标网架规划设计提供技术支撑。在各区域目标网架中,进行主干网架的严重故障计算,并提出安全稳定控制措施,找出电网中的薄弱环节,从电网结构角度分析原因,并提出改进建议。对部分区域电网中的重点输电系统进行多方案的安全稳定性比较,提出推荐方案,为区域电网规划设计提供参考。从各电网需采取的安全稳定控制措施角度出发,认为各区域电网目标网架均满足《电力系统安全稳定导则》的三级安全稳定标准,而区域电网内存在弱联系,电网水电装机比例偏大等问题影响了电网的安全稳定性。区域电网的目标网架应随边界条件的变化而进行调整。