| 过电压的定义和产生 |
| 添加时间：2018/11/17 15:10:29 浏览次数： |
| 电力系统中存在着大量的“储能元件”，这就是储静电能量的电容和储磁能的电感。这些元件组成了各种不同的振荡回路，在正常运行时，这些振荡回路被负载所阻尼或分路，一般不会产生严重的振荡。但在发生故障时，系统接线方式和参数发生改变，就有可能发生谐振。 谐振过电压又可分为线性谐振、参数谐振和铁磁谐振 There are a large number of "energy storage elements" in power system, which are capacitors for storing electrostatic energy and inductances for storing magnetic energy. These components constitute various oscillation loops. In normal operation, these oscillation loops are damped or shunted by loads and generally do not produce serious oscillation. However, when a fault occurs, the connection mode and parameters of the system change, and resonance is possible. Resonance overvoltage can be divided into linear resonance, parametric resonance and ferromagnetic resonance. 线性谐振分析 Linear resonance analysis 自振频率等于或接近电源频率时形成的谐振现象。即ω=ω。=1/√LC。 实际电力系统中，往往可以在设计或运行时避开这种谐振，因此完全满足线性谐振的机会是极少的。但是，即使在接近谐振条件下，往往也会产生很高的过电压,所以要加装TBP过电压保护器。 The resonance phenomenon occurs when the natural frequency is equal to or close to the power frequency. That is, omega = Omega. =1/ LC. In practical power systems, this kind of resonance can often be avoided in design or operation, so the chance to fully satisfy the linear resonance is extremely rare. However, even under the condition of near resonance, it often produces high overvoltage, so TBP overvoltage protector should be installed. 线性谐振过电压幅值受到回路中损耗（电阻）的限制；同时，在有些情况下，由于谐振时电流的急剧增加，回路中的铁磁元件趋向饱和，使系统自动偏离谐振 状态而限制其过电压幅值。 The magnitude of linear resonance overvoltage is limited by the loss (resistance) in the circuit. At the same time, in some cases, due to the sharp increase of current in the circuit, the ferromagnetic components in the circuit tend to be saturated, which makes the system automatically deviate from the resonance state and limits the magnitude of overvoltage. 参数谐振分析 Parametric resonance analysis 系统中某些电感元件的电感参数在某种情况下会发生周期性的变化。在某种参数搭配下，就有可能产生谐振现象。 参数谐振所需能量来源于改变参数的原动机。当电感参数变化时所引入的能量足以补偿回路中的损耗，谐振不断发展。对应于一定的回路电阻，有一定的自激范围。谐振发生后，理论上振幅趋向无穷大，而不像线性谐振那样受到回路电阻的限制。但实际上电感的饱和会使回路自动偏离谐振条件，加装了TBP过电压保护器能使过电压得以限制。 The inductance parameters of some inductors in the system will change periodically under certain circumstances. With certain parameters matching, it is possible to produce resonance. The energy required for parametric resonance comes from the prime mover that changes the parameters. When the inductance parameter changes, the energy introduced is enough to compensate for the loss in the loop, and the resonance develops continuously. Corresponding to a certain loop resistance, there is a certain range of self excitation. After the resonance occurs, the amplitude tends to be infinite in theory, unlike the linear resonance, which is limited by the loop resistance. But in fact, the saturation of inductance will make the circuit deviate from the resonance condition automatically, and the over-voltage can be limited by adding TBP over-voltage protector. 当发电机带有电容性负载，如一段空载线路，在某种参数搭配下，就有可能产生参数谐振现象。有时将这种现象称作发电机的自励磁或自激。发电机投入电网运行前，设计部门要进行自激的校核，一般正常情况下，参数谐振是不会发生的。 When the generator has capacitive load, such as a no-load circuit, it is possible to produce parameter resonance when some parameters are matched. This phenomenon is sometimes referred to as self excitation or self excitation of generators. Before the generator is put into power grid operation, the design department should check the self-excitation. Normally, parameter resonance will not occur. 铁磁谐振分析 Ferromagnetic resonance analysis 电路中带有铁芯的电感元件，会产生饱和现象，其电感不再是常数，而是随着电流或磁通的变化而变化。这种含有非线性电感元件的电路，在满足一定条件时，会发生铁磁谐振,这时就得加装10KV过电压保护器了。 The inductance component with iron core in the circuit will produce saturation phenomenon. Its inductance is no longer constant, but varies with the change of current or flux. This kind of circuit with non-linear inductance elements will produce ferroresonance when certain conditions are met. At this time, 10KV overvoltage protector will have to be installed. 电力系统中发生铁磁谐振的机会是相当多的。国内外运行经验表明，它是电力系统某些严重事故的直接原因。电感L为非线性电感，要精确求解该电路，必须解非线性微分方程 。当谐振发生时，回路中不仅仅有基频分量，还可能存在着高次谐波分量。简单分析该电路时，可忽略高次谐波分量，只考虑基频分量，把谐振下的电压和电流仍看作正弦波求解。 There are quite a lot of Ferroresonance in power system. The operation experience at home and abroad shows that it is the direct cause of some serious accidents in power system. Inductor L is a nonlinear inductance. To solve this circuit accurately, we must solve the nonlinear differential equation. When resonance occurs, there is not only fundamental frequency component but also higher harmonic component in the loop. When the circuit is analyzed simply, the higher harmonic component can be neglected, only the fundamental frequency component can be considered, and the voltage and current under resonance can still be regarded as sinusoidal wave solution. 回路的三个平衡点：a1, a2, a3 a1, a3是稳定平衡点， a2是不稳定平衡点，它经不起任何的扰动，在扰动下会趋向于a1或 a3 。 a1, a3是电路的稳定平衡点，当外加电势E从小增加时，系统首先稳定在a1点。若此时继续增大E，则a1点上移，以致于和a2点重合，系统从点跳跃至a3点。在跃变的过程中，电路发生如下现象：电感铁芯饱和，回路电流急剧增大。电容电压急剧增大,系统由感性变为容性,铁磁谐振的“激发”条件：为了建立起稳定的谐振点a3，回路必须经过强烈的扰动过程，例如发生故障，断路器跳闸，切除故障等。 TBP过电压保护器能起到良好的保护作用,铁磁谐振的“保持”：在铁磁谐振的条件下，即使降低电压，铁磁谐振也不会马上消失。 The three equilibrium points of the loop: a1, a2, A3 a1, A3 are stable equilibrium points, and A2 is unstable equilibrium point. It can not withstand any disturbance and tends to A1 or A3 under disturbance. A1, A3 is the stable equilibrium point of the circuit. When the external potential E increases from small to small, the system first stabilized at A1 point. If E continues to increase at this point, the A1 point moves up to coincide with the A2 point, and the system jumps from the point to the A3 point. In the course of the jump, the following phenomena occur: the core of the inductor is saturated and the current of the loop increases sharply. The capacitor voltage increases sharply and the system changes from inductive to capacitive. The "excitation" condition of ferroresonance is that in order to establish a stable resonance point a3, the circuit must undergo a strong disturbance process, such as failure, circuit breaker tripping, fault removal, etc. TBP overvoltage protector can play a good protective role. Ferromagnetic resonance "hold": Ferromagnetic resonance will not disappear immediately even if the voltage is lowered under the condition of Ferromagnetic resonance. |
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