新能源采用MGP并网的小干扰稳定分析

Renewable Energies and Analysis of Its Small Signal Stability

新能源以日益增高的比例接入电网将带来惯性和阻尼不足的问题,影响新能源电力系统的稳定运行。本文就该问题提出一种基于同步电机的解决思路,即电机对(motor-generator pair,MGP)系统。介绍了新能源采用MGP系统并网的结构和应用场景;建立了基于电机经典模型的小干扰状态方程,通过变换使该方程具有和传统发电机方程相似的形式,更加直观的考察了MGP的惯性和阻尼水平;在此基础上进一步推导了励磁电压恒定时的小干扰状态方程,解释了MGP的阻尼来源。最后,在三机九节点系统中采用模态分析法,对风电在不同渗透率下采用MGP系统并网前后的系统功角振荡模态进行对比分析。结果表明,MGP系统能够为高比例新能源电网提供充足的惯性、阻尼振荡和隔离风电对小干扰稳定的不利影响。

Increasing penetration rate of renewable energy will bring problems of low inertia and low damping,which will affect the stable operation of power system.To solve these problems,this paper proposes a solution based on synchronous machines—motor and generator pair（MGP） system.First,the structure of the MGP used for renewable energy grid-connection and application is introduced.Then the state equations of small signal stability based on classical model of synchronous machine are established.The equations are then transformed to have similar form with the traditional power generator.In this way,the inertia and damping of the MGP can be investigated more intuitively.On this basis,state equations considering constant excitation voltage is derived to explain the source of damping.Finally,mode analysis is used in 3-machine 9-bus system to investigate rotor angle oscillation modes when wind farm is connected to the grid with and without the MGP under different penetration rates.The results show that the MGP can provide enough inertia,damp oscillation and weaken the adverse effects on oscillation modes brought by wind farm.