EX2100  励磁系统 实现发电机并网状态下的限制及保护

EX2100 励磁系统是供给同步发电机励磁电流的电源及其附属设备的统称，主要包括励磁变压器、功率整流单元、励磁调节器、起励、灭磁、保护、监视装置和仪表等。

EX2100 励磁系统一般由两部分组成：一部分用于向发电机的磁场绕组提供直流电流，以建立直流磁场，通常被称作励磁功率输出部分（或称励磁功率单元）；另一部分用于在正常运行或发生故障时调节励磁电流，以满足安全运行的需要，通常被称作励磁控制部分。

励磁系统的技术性能及运行的可靠性，对供电质量、继电保护可靠动作、加速异步电动机自启动和发电机与电力系统的安全稳定运行都有重大影响。

EX2100励磁系统OEL限制器中通过对发电机励磁电流进行采样和检测，实现发电机并网状态下的限制及保护(通过转子热积分12“实现)以及空载运行状态下的过励磁保护。当转子热积分12 超过OEL限制器的限制值时，控制器转入FCR(转子电流控制)运行模式，FCR将根据OEL限制器自动设定为一个较低的调整参考值进行调节。如果在正常运行过程中OEL限制器未启动，FCR输出将保持在高位以确保励磁系统处于AVR (自动)或者FVR(手动)控制方式。EX2100OEL限制器还提供了一个冷却方程对发电机过励状态发生后的转子冷却状况

当OEL限制器动作时，EX2100利用FCR控制器对发电机励磁电流进行调节及限制。在发电机空载运行状况下，发电机励磁电流将被限制在112%(甚至更少)AFNL(发电机空载额定电流值)以防止发电机以及与之相连的变压器过磁通。在发电机并网运行状态下，EX2100将对发电机励磁电流进行限制以防止发电机转子因过热而损坏。然而在励磁电流限制功能启动之前，EX2100也将允许一定的强励输出能力以支持某些故障状态下的系统恢复

EX2100  励磁系统 实现发电机并网状态下的限制及保护

EX2100 excitation system is the general name of the power supply and auxiliary equipment that supply the excitation current of synchronous generator, mainly including excitation transformer, power rectifier unit, excitation regulator, excitation, excitation, excitation, protection, monitoring device and instrument.

The EX2100 excitation system is generally composed of two parts: one part is used to provide DC current to the generator's field winding to establish a DC magnetic field, which is usually called the excitation power output part (or excitation power unit); The other part is used to adjust the excitation current during normal operation or failure to meet the needs of safe operation, and is usually called the excitation control part.

The technical performance and operation reliability of the excitation system have a great impact on the quality of power supply, the reliable operation of relay protection, the acceleration of asynchronous motor self-start and the safe and stable operation of the generator and power system.

By sampling and detecting the generator excitation current in the OEL limiter of the EX2100 excitation system, the generator is limited and protected under grid-connected conditions (through the rotor thermal integral of 12 ") and overexcited protection under no-load operation. When the rotor thermal integral 12 exceeds the limit value of the OEL limiter, the controller switches to the FCR(Rotor Current Control) operating mode, and the FCR is automatically set to a lower adjustment reference value according to the OEL limiter. If the OEL limiter is not activated during normal operation, the FCR output is kept high to ensure that the excitation system is in AVR (automatic) or FVR(manual) control mode. The EX2100OEL limiter also provides a cooling equation for the rotor cooling condition after the generator overexcited state occurs

When the OEL limiter is active, the EX2100 uses the FCR controller to regulate and limit the generator excitation current. In the no-load operation of the generator, the generator excitation current will be limited to 112%(or less)AFNL(generator no-load rating) to prevent over-flux of the generator and the transformer connected to it. In the grid-connected operation of the generator, the EX2100 will limit the generator excitation current to prevent the generator rotor from overheating. However, until the excitation current limiting function is activated, the EX2100 will also allow some strong output capability to support system recovery under certain fault states