讲解感应电压配电系统故障.doc

讲解感应电压配电系统故障供配电系统故障的不同对电动机供电回路的影响也不一样,再起动处理的方法也应有区别。供配电系统故障分单相接地、两相短路、三相短路、对称及不对称等多种故障形式,但对电动机供电回路的影响主要取决于故障的时间及电压降低的幅度。我们常见的有以下三种情况:Power supply and distribution system fault of different effect on the motor power supply circuit is different also, restart processing methods also have difference. Power supply and distribution system of single-phase grounding fault points, two phase short circuit, three-phase short-circuit, symmetric and asymmetric fault in the form, but the motor power supply circuits mainly depends on the influence of the fault time and reduce the magnitude of the voltage. Our common has the following three conditions: 1.瞬时欠压(voltage sag)是瞬时的电压降低,而不是电压的消失,其过程分为电压降低与电压恢复两部分。供配电系统发生故障的瞬时,由于感应电动机转子的磁链不能突变,原有的电流将继续存在,并在定子绕组端子间感应电压。该感应电压并不立即下降,而且能保持相当长时间,此电压称为残余电压。由于残余电压的存在,如果电源断开后,很快又再次合闸,将出现较大的合闸冲击电流及冲击转矩,冲击大小由合闸瞬间电动机的残余电压大小及相位决定。1. The instantaneous undervoltage (voltage sag) is the instantaneous voltage is reduced, rather than the disappearance of the voltage, the process is divided into two parts of the voltage and the voltage recovery. Transient of the failure of power supply and distribution system, due to the induction motor rotor flux linkage cannot mutation, the original current will continue to exist, and the stator winding induction voltage between terminals. The induced voltage is not immediately fall, but also can keep a long time, the voltage is called the residual voltage. Because of the existence of residual voltage if the power disconnect after closing again soon, there will be a great closing impact current and impact torque, impact by closing moment motor size is decided by the size of residual voltage and phase. 2.短时失压与瞬时欠压的区别在于残余电压是否消失。短时失压是电压降低至消失而后电压才恢复。产生的原因主要是继电保护时差配合等原因无法实现快速切除故障。故障发生瞬间,电动机的电流与转矩陡然增大,然后逐渐振荡衰减,而残余电压和转速也开始逐渐下降。电源恢复瞬间,电动机的电流与转矩也会迅速增大,然后逐渐振荡衰减,而转速也开始逐渐上升,经过短时的振荡后稳定在某一数值上。2. The difference between the short-term pressure loss and the instantaneous undervoltage is whether the residual voltage. Loss of pressure in a short time is voltage drops to disappear and then resumed. Reasons mainly relay protection time cooperate to achieve rapid resection fault, etc. Failure occurs, the current and torque of the motor increases abruptly, then gradually oscillation damping, and residual voltage and speed also began to gradually decline. Instant power supply recovery, the electric current and torque of the motor will increase rapidly, then gradually oscillation damping, and speed also began to rise gradually, after short time of oscillation stability on a numerical value. 供配电系统发生短时失压时,低压电动机交流接触器已断开,非再起动的高压电动机均跳闸,电动机转速下降很多,此时bzt等保护可立即动作。母线电压恢复后,电动机再起动技术的处理应是将全部参加再起动的电动机再起动,但采用的电动机再起动方法与技术不同再起动的过程也各异。Power supply and distribution system in short-term loss of pressure, low pressure motor ac contactor has been disconnected, the restart of the high-voltage motor tripping, motor speed down a lot, while BZT protection you can immediately. Bus voltage recovery, motor processing should be restart technology will all attend restart motor starting again, but the motor starting method and technical process of different restart again also vary. 3.长期失压是指供配电系统电压消失时间通常大于10秒的故障。当电动机所在的母线发生长期无法恢复的故障时,电动机已全部停止运转。为了防止电动机随供配电系统的恢复同时再起动而造成的设备事故及人身伤亡,必须清除全部电动机的再起动信息。3. Long-term voltage disappear time refers to the power supply system pressure loss is generally larger than that of 10 seconds of failure. When motor bus long-term unable to recover when a failure occurs, the motor has stopped running. Recovery at the same time in order to prevent the motor with the power supply system restart the equipment caused by accidents and personal injury, must be purged of all motor starter information again. 二、电动机再起动方法Second, the motor starting method again 1.无控式再起动方法1. No control approach for starting again 在供配电系统故障后电压恢复瞬时,按电动机的运行信息,立即将所有参加膨润土防水毯再起动的电动机全部同时再起动既为无控式再起动方法。该方法电路简单,使用电器元件很少,费用低,但存在不少缺点。比如:受到供配电系统容量的限制不能完成全部运行电动机均参加再起动;可因电动机残余电压而产生电流及转矩冲击;由于多台电动机同时起动会产生很大的非周期冲击电流,可能造成变压器跳闸,同时也会造成电动机端电压显著下降,电动机最大转矩低于负载转矩,使再起动失败;无法防止短时再次再起动以及再起动时间过长。Instantaneous voltage recovery after power supply and distribution system fault, according to the running information of the motor, immediately put all to restart motor restart all at the same time for no controlled restart method. Circuit is simple, the method using the electrical components is small, low cost, but there are a lot of shortcomings. Such as: subject to the conditions of power supply and distribution system capacity couldnt finish all running motor is to restart; Can be caused by residual voltage motor current and impact torque; Due to electric motor starting at the same time can produce a lot of aperiodic impact current, may cause transformer tripping, at the same time also can cause a significant reduction in the voltage of the motor, peak torque of the motor under load torque, the starting failure again; Unable to prevent short-term to restart again and again starting time is too long. 2.可控式再起动方法2. A controlled restart method (1)时差控制式电动机群分批再起动(1) time controlled electric fleet of partial restart 时差控制式电动机群分批再起动方法是预先将全部参加再起动的电动机分为固定的多个批次,每台电动机固定在一个批次中,每批再起动电动机固定一个水性油墨再起动时间,各批次再起动时间有一个时差,而且再起动时间越长时差越大。Jet lag controlled electric fleet of partial restart method is in advance all the motor of the restart can be divided into fixed multiple batches of each motor is fixed in a batch, each batch of starting motor fixed another restart time, each batch restart time there is a time difference, and restart the longer the time difference is bigger. 时差控制式电动机群分批再起动的优点是控制方法简单,主要缺点是时差难以选择。时差选大了会使再起动过程拖延很长时间,最后一批再起动电动机几乎是在完全停转的情况下满载起动,这使得许多电动机因过电流而跳闸;时差选小了会出现相邻批次的再起动电流叠加,造成母线电压下降。Partial restart time controlled electric machines control method of the method is simple, the main drawback is the time difference is difficult to choice. Jet lag picked the big will make delay to the starting process for a long time, the last of the starting motor is almost completely stalled again under the condition of full load starting, this makes many trip for over current of the motor; Time choose the small appear adjacent batches again starting current stack, causing the deterioration of busbar voltage. (2)电压控制式电动机群分批再起动(2) partial restart voltage control type electric machines 电压控制式电动机群再起动方法也是预先将全部参加再起动的电动机分为固定的许多批次,每台电动机也固定在一个批次中。正常运行时监测电动机群的母线电压,故障后电压恢复时用再起动电动机群的母线电压控制各批电动机完成再起动任务。该方法与电压与电流控制式电动机群再起动方法相比简单一点,但因为在再起动过程中再起动电流的变化很大,而母线电压变化较小,仅用母线电压控制很难实现监测电动机的再起动状态。Voltage control type electric fleet restart method is in advance all the motor of the restart can be divided into fixed many batches of each motor is fixed in a batch. Normal run time monitoring electric fleet of busbar voltage, voltage restoration after fault in the restart electric fleet of busbar voltage control of each batch of motor restart mission. The method and the voltage and current control type electric fleet restart method is a little bit more simple, but because in the process of restart again starting current of change is very big, and bus voltage change is small, with only busbar voltage control is difficult to implement monitoring motor starting again. (3)电压与电流控制式电动机群分批再起动(3) the voltage and current control type electric fleet of partial restart 与上述两种方法一样,该方法也是预先将全部参加再起动的电动机分为固定的许多批次,每台电动机也固定在一个批次中。正常运行时监测电动机群的母线电压,而在故障后电压恢复时是用再起动电动机群