基于统一潮流建模及灵敏度分析的电-气网络相互作用机理

随着燃气轮机和电转气技术的发展,电网和天然气网的耦合程度不断加深,两者之间的相互影响受到了密切关注。从潮流算法与灵敏度分析两方面针对现有电-气网耦合机理研究的不足进行改进。首先,建立了电网-天然气网统一潮流模型,并采用变量压缩的方法简化了方程维数,基于管存模型考虑了天然气传输的慢时间尺度特性。同时,为避免传统牛顿法应用于天然气网潮流求解对状态初值选择的敏感性,提出采用牛顿下山法对统一潮流模型进行求解。其次,基于灵敏度分析并以电-气耦合节点气压-注入功率灵敏度为关键表征量,提出用于电网-天然气网耦合作用机理分析的综合灵敏度指标,以期为2个网络联合运行提供决策帮助。算例分析验证了所提算法的有效性,综合对比探究了燃气轮机和电转气耦合环节下电网-天然气网的相互作用特性,并验证了天然气网的管道存储特性在应对系统扰动时的积极作用。

Interaction Mechanism of Electricity-Gas Network Based on Unified Power Flow Modeling and Sensitivity Analysis

With the development of gas turbine and power to gas, the coupling degree of power grid and natural gas network is being deepen, and the mutual influence between them has recieved much attention. In this paper, the shortcomings of current researches on the mutual influence between power grid and natural gas network are overcomed from two aspects: power flow algorithm and sensitivity analysis. Firstly, the unified power flow model of integrated electricity and natural gas system is established. The model simplifies the equation dimension by means of reducing variables, and the model considers the slow time-scale characteristics of natural gas transmission based on the line-pack model. At the same time, in order to avoid the sensitivity of traditional Newton method to the choice of initial state value in the power flow solution of natural gas network, the Newton descent method is proposed to solve the unified power flow model. Furthermore, based on the sensitivity analysis method, with the sensitivity of gas pressure-injected power of electricity-gas coupling node as the key characterisitic quantity, a comprehensive sensitivity index for the analysis of the coupling mechanism of integrated electricity and natural gas system is proposed in order to provide decision-making assistance for the joint operation of the two networks. The analysis of examples verifies the effectiveness of the proposed algorithm. By comprehensively comparing and exploring the interaction characteristics of integrated electricity and natural gas system with the coupling of gas turbine and power to gas, the positive role of line-pack characteristics of the natural gas network in response to system disturbances is verified.