应对特高压直流接地极电流影响的油气管道大功率阴保系统参数优化配置

Optimal Configuration of High-power Cathodic Protection System Parameters for Coping With the Influence of UHVDC Grounding Electrode Current on Oil and Gas Pipelines

特高压直流输电工程不同工况下接地极电流变化巨大,单极大地回路运行时可高达6.25kA,现有油气管道阴保系统已无法完全应对入地电流的干扰影响,亟需配置具有双向输出功能的大功率阴保系统。分别以管道等效年腐蚀速率和管地电位差进行评估,建立大功率阴保系统参数的优化目标函数;将混沌粒子群优化算法应用于油气管道大功率阴保系统参数优化配置,并基于粒子间的欧氏距离提出粒子群稳定性判据。就典型直流工程与埋地油气管道的干扰问题,对油气管道干扰影响进行评估,并对大功率阴保系统参数进行优化配置。结果表明,以等效年腐蚀速率评估时,需综合考虑直流工程在不同运行工况下的影响;采用优化配置的大功率阴保系统,可满足等效年腐蚀速率限值要求。以管地电位差评估时,采用大功率阴保系统可将管道管地电位差控制在限值范围,但接地极在阴极和阳极不同状态下运行时,优化得到的大功率阴保电源位置不同,需优先保证接地极阴极运行时管地电位差满足限值要求,以有效缓解对管道的腐蚀影响。研究结果为应对特高压直流接地极电流影响的埋地油气管道自适应大功率阴保系统研究提供了参考。

The grounding current of UHVDC projects varies greatly under different operating conditions.The current amplitude can reach 6.25 kA under the monopole earth-return operation.The existing cathodic protection system can hardly deal with the influence of the grounding current on oil and gas pipelines.So it is necessary to configure high-power cathodic protection systems(HCPS)with bidirectional output function to weaken this adversary influence.To achieve optimal configuration for HCPS,an objective function is established which takes into account equivalent annual corrosion rate and pipe-to-soil potential(PSP).The optimal configuration is achieved based on chaotic particle swarm optimization and a stability criterion of particle swarm is proposed based on Euclidean distance.The interference evaluation and protective configuration of a typical engineering case are analyzed based on the proposed method.The results show that the grounding current under different operating conditions should be considered when evaluated by equivalent annual corrosion rate.The limit value of equivalent annual corrosion rate can be fulfilled by applying HCPS.The PSP can also satisfy the criteria when the grounding electrode is under cathode condition or anode condition.However,the current source positions are different under different operating conditions.The PSP criteria for cathode operation should be a priority to mitigate the corrosion impact more effectively.This research provides a reference for the study of adaptive HCPS.