0 导语

作为一种灵活性资源，储能在现代电力系统中扮演着重要角色。为提升规划可靠性及储能利用价值，本文提出了安全约束下考虑多阶段校正控制的储能与线路联合规划，同时，引入了Benders分解算法将原问题分解为主问题及两个子问题以加快求解。敬请关注本期推荐。

Security Constrained Co-Planning of Transmission Expansion and Energy Storage

Wei Gan, Xiaomeng Ai, Jiakun Fang, Mingyu Yan, Wei Yao, Wenping Zuo, JinyuWen

期刊：Applied Energy

Abstract/Highlight  

This paper presents a security-constrained co-planning of transmission line expansion and energy storage with high penetration of wind power. The energy storage can not only improve the accommodation of renewable generation but also help to mitigate the emergency overflow under the post-contingency state. Also, the adjustment capabilities of the wind farms are considered, and the risk of excessive wind curtailment under the post-contingency state is assessed quantitatively. The coordinated multistage corrective control strategy for the battery storage, the pumped storage, thermal generators, and wind farms is studied. The mixed-integer linear programming problem based on the proposed corrective control strategy has been formulated. The Benders decomposition algorithm is introduced to divide the co-planning problem into one master problem and two sub-problems. In the master problem, the system is operating under normal conditions, so the security constraints are not considered. It minimizes the sum of the investment cost of newly built facilities and the operational cost. In the sub-problems, the corrective control during different post-contingency stages is formulated, minimizing the risk costs under fault conditions. The two-step technique is developed to generate the Benders cuts from the mixed-integer linear programming sub-problems, and return to the master problem. The real-world power system in Gansu, China is studied to validate the applicability and scalability of the proposed model and solution technique. The results denote that the co-planning model with security constraints is profitable in the real power system, with savings of 25% for the newly built transmission lines and a 5.5% reduction in total cost.

1 项目背景

作为一种灵活性资源，储能在现代电力系统中扮演着重要角色并逐渐得到越来越广泛的应用。现阶段，储能高昂的投资成本成为制约其发展应用的一大障碍，因此，有必要进行储能的优化配置研究以实现储能投资成本与经济效益的均衡。现有关于储能与电力线路联合规划的研究进一步发挥了储能疏导线路拥塞、延缓线路扩容的作用。然而，现有的储能与电力线路联合规划并未考虑线路N-1故障等紧急状况，且并未考虑储能在N-1故障中所能发挥的作用。这一方面难以保证系统的运行可靠性，另一方面，对灵活的储能资源利用也不充分。

2 论文所解决的问题及意义

围绕安全约束下的储能与电力线路联合规划问题，为应对N-1紧急潮流越限，提出了多阶段多类型的储能校正控制策略，有效利用了风电的调节容量并量化了其风险成本，引入了Benders分解算法将原问题分解为主问题及两个子问题以加快求解。

3 论文重点内容

1） 安全约束联合规划模型框架

该模型以投资成本、运行成本以及故障后的风险成本之和最小为优化目标。模型由主问题、子问题两部分构成。对于主问题，其以投资成本与运行成本之和最小为目标，决策出规划方案与故障前设备出力。对于子问题，其对给定的规划方案与故障前设备出力进行可行性校验，并计算风险成本，即最优性校验，并返回相应的Benders割到主问题。

图1  模型框架

2） 多类型多阶段储能校正过程

基于电力线路紧急越限热特性，本文提出了多阶段校正控制策略。具体来说，校正控制过程分为三个阶段，这主要由电力线路所允许的三阶段紧急越限功率决定，包括短期越限功率，中期越限功率与长期越限功率，三者依次减小，如图2所示。

图2  故障后3阶段校正过程

线路N-1故障后电池储能与抽水蓄能的校正过程分别如图3、图4所示，在故障后第一阶段，运行状况更加灵活的电池储能迅速反应参与校正，而此时抽水蓄能由于响应时间相对慢不参与第一阶段的校正。在第二阶段，电池储能线性地减少出力，同时抽水蓄能线性地增加出力以弥补电池出力减少造成的缺额，当抽水蓄能的出力达到最大后，由于存在能量限制，其将线性地减少出力直至为0。在第三阶段，电池储能与抽水蓄能额出力均为0，功率缺额由常规机组调整出力以补充。

图3  电池储能校正过程

图4  抽水蓄能校正过程

故障校正前后的储能能量之差如下式所示。其中式（1）为电池储能故障校正前后的能量差，式（2）为抽水蓄能故障校正前后的能量差

3） Benders分解算法

由于大规模N-1故障场景及多时段的存在，本文的模型复杂度高，难以求解。因此本文引入Benders分解算法将原模型分解为一个主问题与两个子问题，并交替求解主问题、子问题。

步骤1）：求解主问题，确定规划方案与故障前设备出力

步骤2）：在给定的规划方案与故障前设备出力下，检查第一个子问题的约束是否满足，不满足则返回Benders割到主问题并回到步骤1），否则继续到步骤3）

步骤3）：检查第二个子问题的约束是否满足，不满足则返回Benders割到主问题并回到步骤1），否则继续到步骤4）

步骤4）：检查两个子问题的最优性是否满足，不满足则返回Benders割到主问题并回到步骤1），否则结束计算。

图5  Benders分解流程图

Conclusion

This paper presents a security-constrained co-planning of the transmission lines and energy storage.

1) The multistage corrective control of the battery energy storage system and the pumped energy storage system is modeled in this paper, which considers the distinguishing features of these two energy storage technologies. The adjustment capabilities of the wind farms are also considered in the multistage corrective control.

2) The allocation of energy storage systems is optimized in coordination with the transmission expansion, taking operational costs, investment costs and risk costs into account. The operational costs equal the fuel costs under normal operating conditions. The costs under the post-contingency state are risk costs caused by excessive wind curtailment.

3) The formulated mixed-integer linear programming problem is solved by using Benders decomposition. The two-step technique is developed to generate the Benders cuts from the mixed-integer linear programming sub-problems.

4) The results obtained from the Gansu provincial system indicate that the co-planning model with security constraints is profitable in the practical power system, with savings of 25% for the newly built transmission lines and a 5.5% reduction in the total cost.

引文信息

Wei Gan, Xiaomeng Ai, Jiakun Fang, Mingyu Yan, Wei Yao, Wenping Zuo, Jinyu Wen,et al. Security Constrained Co-planning of Transmission Expansion and Energy Storage[J]. Appl. Energy, vol. 239, pp. 383-394, Apr. 2019.

https://www.sciencedirect.com/science/article/pii/S0306261919301953

作者简介：

Wei Gan received the B.E. degree in electrical engineering from Huazhong University of Science and Technology (HUST), China, in 2016. He is currently pursuing his PhD degree at HUST. His research interests include energy storage planning, and electrified transportation planning.

Xiaomeng Ai received the B.Eng degree in mathematics and applied mathematics and Ph.D. in electrical engineering in 2008 and 2014, respectively, both from Huazhong University of Science and Technology (HUST), Wuhan, China. Currently he is a lecturer at HUST. His research interests include robust optimization theory in power system, renewable energy integration, and integrated energy market.

Jiakun Fang received the B.Sc. and Ph.D. degrees from Huazhong University of Science and Technology (HUST), China, in 2007 and 2012, respectively. He was with the Department of Energy Technology, Aalborg University, Aalborg, Denmark from 2012 to 2019. Currently, he is a Professor in Huazhong University of Science and Technology (HUST), Wuhan, China His research interests include power system dynamic stability control, power grid complexity analysis, and integrated energy system.

Mingyu Yan received the B.S. degree from the College of Electrical Engineering, Zhejiang University, Hangzhou, China, in 2016 and the M.S. degree from the Huazhong University of Science and Technology, Wuhan, China in 2018. He is currently working toward the Ph.D. degree with the Robert W. Galvin Center for Electricity Innovation, Illinois Institute of Technology, Chicago, IL, USA. His research interests include power system operation and planning, multiple energy system integration, and microgrid control.

Wei Yao received the B.S. and Ph.D. degrees in electrical engineering from Huazhong University of Science and Technology (HUST), Wuhan, China, in 2004 and 2010, respectively. He was a Post-Doctoral Researcher with the Department of Power Engineering, HUST, from 2010 to 2012 and a Postdoctoral Research Associate with the Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, U.K., from 2012 to 2014. Currently, he has been an Associate Professor with the School of Electrical and Electronics Engineering, HUST, Wuhan, China. His current research interests include power system stability analysis and control, renewable energy, HVDC and DC Grid, and application of artificial intelligence in Smart Grid.

Wenping Zuo received the B.S. degree and Ph.D degree in electrical engineering from Huazhong University of Science and Technology (HUST), Wuhan, China, in 2009 and 2017, respectively. Currently he is a Post-Doctoral Research Fellow with HUST. His research interests include DC grid key equipment, energy storage, and renewable energy integration.

Jinyu Wen (M’10) received his B.Eng. and Ph.D. degrees all in electrical engineering from Huazhong University of Science and Technology (HUST), Wuhan, China, in 1992 and 1998, respectively. He was a visiting student from 1996 to 1997 and research fellow from 2002 to 2003 all at the University of Liverpool, UK, and a senior visiting researcher at the University of Texas at Arlington, USA in 2010. From 1998 to 2002 he was a director engineer in XJ Electric Co. Ltd. in China. In 2003 he joined the HUST and now is a Professor at HUST. His current research interests include renewable energy integration, energy storage application, DC grid, and power system operation and control.

期刊简介：Applied Energy，一区SCI，影响因子：8.4。收稿范围包括：化石能源和可再生能源的创新技术和系统，清洁能源的工业利用和家庭使用，同时包括建模和预测，以及能源政策及其对环境、社会和经济的影响。