CN106849150B - A Commutation Failure Predictive Control System and Method Based on Harmonic Voltage Detection - Google Patents
A Commutation Failure Predictive Control System and Method Based on Harmonic Voltage Detection Download PDFInfo
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Abstract
本发明涉及一种基于谐波电压检测的换相失败预测控制系统及方法，1)谐波电压检测模块根据换流母线上需检测的换相电压中的低次谐波分量次数，对其进行检测得到换相电压的各低次谐波分量；2)谐波电压计算模块根据得到的换相电压中各低次谐波分量，分别计算各低次谐波分量电压相对于基波电压的含有率；3)比较模块根据预设的换相失败预测的启动门槛值，将各次谐波电压含有率与启动门槛值进行比较，根据比较结果产生启动信号，并发送到控制模块；4)控制模块根据比较模块与现有控制系统中零序电压检测模块产生启动信号的先后顺序，采取相应措施对换流母线的换相失败进行预测控制。本发明可以在电力系统控制技术领域中广泛应用。
The present invention relates to a commutation failure prediction control system and method based on harmonic voltage detection. 1) The harmonic voltage detection module performs Detecting each low-order harmonic component of the commutation voltage; 2) The harmonic voltage calculation module calculates the content of each low-order harmonic component voltage relative to the fundamental voltage according to each low-order harmonic component in the obtained commutation voltage 3) The comparison module compares the content rate of each harmonic voltage with the start threshold value according to the preset starting threshold value of commutation failure prediction, generates a starting signal according to the comparison result, and sends it to the control module; 4) controls According to the order of starting signals generated by the comparison module and the zero-sequence voltage detection module in the existing control system, the module takes corresponding measures to predict and control the commutation failure of the commutation bus. The invention can be widely applied in the technical field of power system control.
Description
技术领域technical field
本发明涉及电力系统控制技术领域，特别是关于一种基于谐波电压检测的换相失败预测控制系统及方法。The invention relates to the technical field of power system control, in particular to a commutation failure prediction control system and method based on harmonic voltage detection.
背景技术Background technique
换相失败是常规电压源换流器(LCC-HVDC)逆变侧换流器的常见故障。换相失败主要是由交流系统扰动引起，它会造成逆变侧直流电压降低、直流电流增大，引起换流器应力增加，严重时甚至可能造成直流系统降额运行。为了减小换相失败概率，在高压直流控制系统中CFPREV(换相失败预测控制)常通过检测换相电压中的零序分量或对换相电压进行α/β变换，来预防由交流系统单相接地故障和三相短路故障引起的换相失败。针对换相失败的预测和预防控制，学者们提出了多种改进的预测算法，包括提高过零点附近检测速度和准确性的方法、采用自适应模糊控制或PI控制应对不同直流控制模式及运行工况的影响。但在上述的研究中，尚未有研究对谐波畸变引起换相失败的现象提出有效的应对措施。Commutation failure is a common failure of the inverter side converter of conventional voltage source converter (LCC-HVDC). The failure of commutation is mainly caused by the disturbance of the AC system, which will cause the DC voltage on the inverter side to decrease, the DC current to increase, and the stress of the converter to increase. In severe cases, it may even cause the DC system to derate. In order to reduce the probability of commutation failure, CFPREV (commutation failure predictive control) in high-voltage DC control systems often prevents the commutation voltage from being caused by the AC system by detecting the zero-sequence Commutation failures caused by phase-to-ground faults and three-phase short-circuit faults. For the prediction and preventive control of commutation failure, scholars have proposed a variety of improved prediction algorithms, including methods to improve the detection speed and accuracy near the zero crossing point, and adopt adaptive fuzzy control or PI control to deal with different DC control modes and operating conditions. impact of the situation. However, in the above-mentioned studies, there is no research to propose effective countermeasures to the phenomenon of commutation failure caused by harmonic distortion.
此外，随着我国高压直流工程大量投产，在华东、山东等区域都已经形成或正在形成直流的多馈入系统。由于直流落点密集，单台交流变压器充电的励磁涌流可能造成多个直流发生换相失败，而励磁涌流的衰减周期很长，增加了直流多次反复换相失败的风险。采用加装合闸电阻或采用专门设备对变压器进行消磁无疑将极大增加电网建设投资和运行费用。In addition, with the large-scale production of high-voltage DC projects in China, DC multi-infeed systems have been formed or are being formed in East China, Shandong and other regions. Due to the dense DC drop point, the excitation inrush current charged by a single AC transformer may cause multiple DC commutation failures, and the decay period of the excitation inrush current is very long, which increases the risk of repeated DC commutation failures. Adding closing resistors or using special equipment to demagnetize the transformer will undoubtedly greatly increase the investment and operation costs of power grid construction.
发明内容Contents of the invention
针对上述问题，本发明的目的是提供一种基于谐波电压检测的换相失败预测控制系统及方法，该方法简便有效、不增加额外的变压器消磁设备，与现有换相失败预防控制算法配合，能有效预防因大型交流变压器充电过程中励磁涌流引起的多次反复换相失败问题。In view of the above problems, the object of the present invention is to provide a commutation failure prediction control system and method based on harmonic voltage detection, which is simple and effective, does not add additional transformer demagnetization equipment, and cooperates with the existing commutation failure prevention control algorithm , which can effectively prevent multiple repeated phase commutation failures caused by inrush currents during the charging process of large AC transformers.
为实现上述目的，本发明采取以下技术方案：一种基于谐波电压检测的换相失败预测控制系统，其特征在于：其包括谐波电压检测模块、谐波电压计算模块、比较模块以及控制模块；所述谐波电压检测模块用于对换流母线上换相电压中的低次谐波进行实时检测，并将检测得到的各次谐波分量发送到所述谐波电压计算模块；所述谐波电压计算模块用于根据得到的各低次谐波分量，计算各低次谐波分量电压的含有率，并发送到所述比较模块；所述比较模块用于对各次谐波电压的含有率与预设的启动门槛值进行比较，根据比较结果产生启动信号并发送到所述控制模块；所述控制模块根据所述比较模块以及现有控制系统中零序电压检测模块发送的启动信号的先后顺序，对换流母线的换相失败进行预测及控制。To achieve the above object, the present invention adopts the following technical solutions: a commutation failure prediction control system based on harmonic voltage detection, characterized in that it includes a harmonic voltage detection module, a harmonic voltage calculation module, a comparison module and a control module The harmonic voltage detection module is used for real-time detection of low-order harmonics in the commutation voltage on the commutation bus, and sends the detected harmonic components to the harmonic voltage calculation module; The harmonic voltage calculation module is used to calculate the content rate of each low-order harmonic component voltage according to the obtained low-order harmonic components, and send it to the comparison module; The content rate is compared with the preset start threshold value, and a start signal is generated according to the comparison result and sent to the control module; the control module is based on the start signal sent by the comparison module and the zero-sequence voltage detection module in the existing control system To predict and control the commutation failure of the commutation bus.
一种基于所述系统的谐波电压检测的换相失败预测控制方法，其特征在于包括以下步骤：1)谐波电压检测模块根据确定的换流母线上需检测的换相电压中的低次谐波分量次数，对其进行实时检测得到换相电压的各低次谐波分量，并发送到谐波电压计算模块；2)谐波电压计算模块根据得到的换相电压中各低次谐波分量，分别计算各低次谐波分量电压相对于基波电压的含有率，并发送到比较模块；3)比较模块根据预设的换相失败预测的启动门槛值，将各次谐波电压含有率与启动门槛值进行比较，根据比较结果产生启动信号，并发送到控制模块；4)控制模块根据比较模块与现有控制系统中零序电压检测模块产生启动信号的先后顺序，采取相应措施对换流母线的换相失败进行预测控制。A commutation failure predictive control method based on the harmonic voltage detection of the system, characterized in that it includes the following steps: 1) The harmonic voltage detection module is based on the determined low-order commutation voltage to be detected on the commutation bus Harmonic component times are detected in real time to obtain the low-order harmonic components of the commutation voltage, and sent to the harmonic voltage calculation module; 2) The harmonic voltage calculation module is based on the obtained low-order harmonic components of the commutation voltage Components, respectively calculate the content rate of each low-order harmonic component voltage relative to the fundamental voltage, and send it to the comparison module; 3) The comparison module calculates the content of each harmonic voltage 4) The control module takes corresponding measures according to the order in which the comparison module and the zero-sequence voltage detection module in the existing control system generate the startup signals. The commutation failure of the commutation bus is predictively controlled.
所述步骤2)中，谐波电压含有率的计算公式为：In described step 2), the calculation formula of harmonic voltage content rate is:
式中，Dn为第n次谐波含有率，En为第n次谐波相对地电压均方根值；Eph为基波相对地电压均方根值。In the formula, D n is the nth harmonic content rate, E n is the root mean square value of the nth harmonic relative to the ground voltage; E ph is the root mean square value of the fundamental wave relative to the ground voltage.
所述步骤3)中，将各次谐波电压含有率与启动门槛值进行比较的方法为：如果任意次谐波的含有率超过预设的启动门槛值，则产生启动信号；如果各次谐波电压含有率均低于启动门槛值，则不动作。In the step 3), the method of comparing the content ratio of each harmonic voltage with the startup threshold value is as follows: if the ratio of any harmonic voltage exceeds the preset startup threshold value, a startup signal is generated; If the wave voltage content rate is lower than the start threshold, no action will be taken.
所述步骤4)中，控制模块根据接收到的比较模块的启动信号以及现有控制系统中零序电压检测模块的启动信号的先后顺序，进行换相失败的预测控制的方法为：如果比较模块输出启动信号先于现有控制系统中的零序电压检测模块的启动信号，则直接启动逆变侧角度控制，使熄弧角增加5度；如果现有控制系统中的零序电压检测模块的启动信号先于比较模块的启动信号，则产生一个保持信号，帮助保持零序电压环节增加的熄弧角直至谐波电压含有率低于启动门槛值。In said step 4), the control module carries out the method of predictive control of commutation failure according to the start signal of the comparison module received and the sequence of the start signal of the zero-sequence voltage detection module in the existing control system: if the comparison module If the output start signal is prior to the start signal of the zero-sequence voltage detection module in the existing control system, the angle control on the inverter side will be started directly, so that the arc extinguishing angle will increase by 5 degrees; if the zero-sequence voltage detection module in the existing control system The start signal is prior to the start signal of the comparison module, and a hold signal is generated to help maintain the increased arc extinguishing angle of the zero sequence voltage link until the harmonic voltage content rate is lower than the start threshold.
本发明由于采取以上技术方案，其具有以下优点：1、本发明对实际谐波对换相电压的影响程度进行了研究，通过检测并比较低次谐波分量电压含有率是否超过预设的启动门槛值，实现提前触发，降低了谐波引起换相失败的风险。2、本发明控制模块根据比较模块以及现有控制系统的零序电压检测模块产生的启动信号进行换相失败的预测控制，不仅可以在现有控制系统前实现提前触发，还可以在帮助现有控制系统持续输出有效信号，进一步提高了对换相失败预测的准确性。3、本发明中启动门槛值的确定同时考虑了换相失败预测以及系统背景噪声两个因素，因而既能及时预防换相失败又避免了背景谐波的存在导致的误启动，判断更加准确。本发明物理概念明确，工程实施简单易行，便于实际应用，以极低的代价有效解决大型变压器充电过程中产生的励磁涌流引起附近逆变站发生多次反复换相失败的问题。本发明可以在电力系统控制技术领域中广泛应用。Due to the adoption of the above technical scheme, the present invention has the following advantages: 1. The present invention studies the degree of influence of actual harmonics on the commutation voltage, and detects and compares whether the low-order harmonic component voltage content exceeds the preset start-up Threshold value, triggering in advance, reducing the risk of commutation failure caused by harmonics. 2. The control module of the present invention performs predictive control of commutation failure according to the starting signal generated by the comparison module and the zero-sequence voltage detection module of the existing control system, which can not only realize early triggering before the existing control system, but also help existing The control system continuously outputs effective signals, which further improves the accuracy of commutation failure prediction. 3. The determination of the starting threshold value in the present invention takes into account both commutation failure prediction and system background noise, so it can prevent commutation failure in time and avoid false start caused by the existence of background harmonics, making the judgment more accurate. The invention has a clear physical concept, is simple and easy to implement, is convenient for practical application, and effectively solves the problem of multiple repeated phase commutation failures in nearby inverter stations caused by the excitation inrush current generated during the charging process of a large transformer at a very low cost. The invention can be widely applied in the technical field of power system control.
附图说明Description of drawings
图1是本发明中基于谐波电压检测的换相失败预测控制系统示意图；Fig. 1 is a schematic diagram of a commutation failure prediction control system based on harmonic voltage detection in the present invention;
图2(a)是大型交流变压器典型空充励磁涌流波形中换流母线电压及励磁涌流；Figure 2(a) shows the commutation bus voltage and inrush current in a typical no-charge excitation inrush waveform of a large AC transformer;
图2(b)是大型交流变压器典型空充励磁涌流波形中换流母线电压谐波分量；Figure 2(b) shows the harmonic components of the commutation bus voltage in the typical no-charge excitation inrush waveform of a large AC transformer;
图3是本发明实施例中高岭背靠背直流及附近的绥中电厂(2*1000MW机组)系统的单线图；Fig. 3 is the one-line diagram of Kaolin back-to-back DC and nearby Suizhong Power Plant (2*1000MW unit) system in the embodiment of the present invention;
图4是未采用本发明时，绥中电厂一台升压变压器空充造成高岭背靠背换流站发生四次换相失败的仿真结果；图中从上至下依次为三相交流电压，直流电压，直流电流，换流变Y接绕组阀侧电流，换流变△接绕组阀侧电流，逆变侧熄弧角，中性母线直流电流；Fig. 4 is when the present invention is not adopted, the simulation result of four phase commutation failures in the back-to-back converter station of Gaoling caused by a step-up transformer in Suizhong Power Plant; Voltage, DC current, converter transformer Y connected to winding valve side current, converter transformer △ connected to winding valve side current, inverter side arc extinguishing angle, neutral bus DC current;
图5是采用本发明后，绥中电厂一台升压变压器空充仅造成高岭换流站第一次换相失败的仿真结果；图中从上至下依次为三相交流电压，直流电压，直流电流，换流变Y接绕组阀侧电流，换流变△接绕组阀侧电流，逆变侧熄弧角，中性母线直流电流。Fig. 5 is after adopting the present invention, the empty charge of a step-up transformer of Suizhong Power Plant only causes the simulation result of phase commutation failure for the first time of Gaoling converter station; , DC current, the converter transformer Y is connected to the winding valve side current, the converter transformer △ is connected to the winding valve side current, the inverter side arc extinguishing angle, and the neutral bus DC current.
具体实施方式Detailed ways
下面结合附图和实施例对本发明进行详细的描述。The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.
如图1所示，为了降低大型变压器充电过程中励磁涌流引起附近直流逆变站多次反复换相失败风险，本发明提供一种基于谐波电压检测的换相失败预测控制系统，包括谐波电压检测模块、谐波电压计算模块、比较模块以及控制模块。谐波电压检测模块用于对换流母线上换相电压中的低次谐波进行实时检测，并将检测得到的各次谐波分量发送到谐波电压计算模块。谐波电压计算模块用于根据得到的各低次谐波分量，计算各低次谐波分量电压的含有率，并发送到比较模块。比较模块用于对各次谐波电压的含有率与预设的启动门槛值进行比较，根据比较结果产生启动信号并发送到控制模块。控制模块根据比较模块以及现有控制系统中零序电压检测模块发送的启动信号的先后顺序，对换流母线的换相失败进行预测及控制。As shown in Figure 1, in order to reduce the risk of repeated commutation failures at nearby DC inverter stations caused by inrush currents during the charging process of large transformers, the present invention provides a commutation failure prediction and control system based on harmonic voltage detection, including harmonic A voltage detection module, a harmonic voltage calculation module, a comparison module and a control module. The harmonic voltage detection module is used for real-time detection of low-order harmonics in the commutation voltage on the commutation bus, and sends the detected harmonic components to the harmonic voltage calculation module. The harmonic voltage calculation module is used to calculate the content rate of each low-order harmonic component voltage based on the obtained low-order harmonic components, and send it to the comparison module. The comparison module is used to compare the content ratio of each harmonic voltage with the preset starting threshold value, generate a starting signal according to the comparison result and send it to the control module. The control module predicts and controls the commutation failure of the commutation bus according to the sequence of start signals sent by the comparison module and the zero-sequence voltage detection module in the existing control system.
基于上述基于谐波检测的换相失败预测控制系统，本发明还提供一种基于谐波检测的换相失败预测控制方法，其包括以下步骤：Based on the above-mentioned commutation failure prediction control system based on harmonic detection, the present invention also provides a commutation failure prediction control method based on harmonic detection, which includes the following steps:
1)谐波电压检测模块根据确定的换流母线上需检测的换相电压中的低次谐波分量次数，对其进行实时检测得到换相电压的各低次谐波分量，并发送到谐波电压计算模块。1) The harmonic voltage detection module detects the low-order harmonic components of the commutation voltage to be detected on the commutation bus in real time according to the determined order of the low-order harmonic components of the commutation voltage, and sends them to the harmonic Wave voltage calculation module.
如图2(a)、图2(b)所示，为特高压主变500kV侧合闸的电磁暂态过程，合闸过程中励磁用最大为6.3kA时的励磁涌流波形。从图中可以看出，合闸过程中换流母线电压含有大量2、3、4、5次谐波分量。对合闸过程及合闸20ms后换流母线谐波分量的统计数据进行分析，如下表1所示，进一步验证得到在合闸过程中换流母线电压中含有大量2、3、4、5次谐波分量，其中2次谐波分量最大，为117.1kV(39.3％)。As shown in Figure 2(a) and Figure 2(b), it is the electromagnetic transient process of the 500kV side of the UHV main transformer closing. During the closing process, the excitation inrush waveform is at a maximum of 6.3kA. It can be seen from the figure that the commutation bus voltage contains a large number of 2, 3, 4 and 5 harmonic components during the closing process. Analyze the statistical data of the harmonic components of the converter bus during the closing process and 20ms after closing, as shown in Table 1 below. Further verification shows that the voltage of the converter bus during the closing process contains a large number of 2, 3, 4, and 5 times Harmonic components, of which the 2nd harmonic component is the largest, is 117.1kV (39.3%).
表1 特高压主变500kV侧合闸过程换流母线电压谐波含量Table 1 Harmonic content of converter bus voltage during closing process of 500kV side of UHV main transformer
由以上分析可知，根据实际谐波对换相电压的影响程度，本发明认为至少需要检测的谐波次数为2次，3次，4次及5次谐波分量。采用快速傅里叶算法或其他数字滤波器实时检测换相电压中的低次谐波分量，本发明中主要检测的谐波次数为2次、3次、4次及5次谐波分量，以覆盖大型变压器空充励磁涌流的特征谐波频谱。From the above analysis, it can be seen that according to the degree of influence of actual harmonics on the commutation voltage, the present invention considers that at least the harmonics to be detected are 2nd, 3rd, 4th and 5th harmonic components. Adopt fast Fourier algorithm or other digital filters to detect the low-order harmonic component in the commutation voltage in real time, the harmonic order mainly detected in the present invention is the 2nd, 3rd, 4th and 5th harmonic component, with Covering the characteristic harmonic spectrum of large transformer no-charge excitation inrush current.
2)谐波电压计算模块根据得到的换相电压中各低次谐波分量，分别计算各低次谐波分量电压相对于基波电压的含有率，并发送到比较模块。2) The harmonic voltage calculation module calculates the content ratio of each low-order harmonic component voltage relative to the fundamental wave voltage according to the obtained commutation voltage of each low-order harmonic component, and sends it to the comparison module.
将换相电压中的各次谐波分量与基波电压相比，分别计算2次，3次，4次及5次谐波的含有率，其谐波电压含有率的计算公式为：Comparing each harmonic component in the commutation voltage with the fundamental voltage, calculate the 2nd, 3rd, 4th and 5th harmonic content respectively. The formula for calculating the harmonic voltage content is:
式中，Dn为第n次谐波含有率，En为第n次谐波相对地电压均方根值；Eph为基波相对地电压均方根值。In the formula, D n is the nth harmonic content rate, E n is the root mean square value of the nth harmonic relative to the ground voltage; E ph is the root mean square value of the fundamental wave relative to the ground voltage.
3)比较模块根据预设的换相失败预测的启动门槛值，将各次谐波电压含有率与启动门槛值进行比较，根据比较结果产生启动信号，并发送到控制模块。3) The comparison module compares the content ratio of each harmonic voltage with the start threshold value according to the preset start threshold value of commutation failure prediction, generates a start signal according to the comparison result, and sends it to the control module.
启动门槛值的确定受到两个主要因素影响：一是当任意低次谐波含量超过5％时，有很大几率会使直流输电逆变侧换流器发生换相失败；另一个是由于电力系统存在背景谐波，如果启动门槛值太小，可能造成预测模块频繁启动，反而引起直流系统电压和功率波动，同时根据国标规定，背景谐波中较大的3次或5次谐波含有率不应超过1.5％。因而，本发明中将基于谐波电压的换相失败预测启动门槛值取为任意次谐波电压含有率超过基波电压的3％，启动门槛值取3％可以及时预防换相失败发生，同时又不会因为交流系统背景谐波的存在使该判据误启动。The determination of the start-up threshold is affected by two main factors: one is that when any low-order harmonic content exceeds 5%, there is a high probability that the inverter side converter of the DC transmission will fail to commutate; the other is due to the power There are background harmonics in the system. If the startup threshold is too small, it may cause the prediction module to start frequently, which will cause voltage and power fluctuations in the DC system. It should not exceed 1.5%. Therefore, in the present invention, the commutation failure prediction startup threshold value based on harmonic voltage is taken as 3% of the harmonic voltage content rate of any order exceeding the fundamental voltage, and the startup threshold value of 3% can prevent the occurrence of commutation failure in time, and at the same time And the criterion will not be falsely activated due to the existence of background harmonics in the AC system.
将各次谐波电压含有率与启动门槛值进行比较：如果任意次谐波的含有率超过预设的启动门槛值，则产生启动信号；如果各次谐波电压含有率均低于启动门槛值，则不动作。Compare the content of each harmonic voltage with the start threshold: if the content of any harmonic exceeds the preset start threshold, a start signal will be generated; if the content of each harmonic voltage is lower than the start threshold , no action is taken.
4)控制模块根据比较模块与现有控制系统中零序电压检测模块产生启动信号的先后顺序，采取相应措施对换流母线的换相失败进行预测控制。4) The control module takes corresponding measures to predict and control the commutation failure of the commutation bus according to the order in which the starting signal is generated by the comparison module and the zero-sequence voltage detection module in the existing control system.
控制模块根据接收到的比较模块的启动信号以及现有控制系统中零序电压检测模块的启动信号的先后顺序，进行换相失败的预测控制。具体的：The control module performs commutation failure predictive control according to the sequence of the received startup signals of the comparison module and the startup signals of the zero-sequence voltage detection module in the existing control system. specific:
如果比较模块输出启动信号先于现有控制系统中的零序电压检测模块的启动信号，则直接启动逆变侧角度控制，使熄弧角增加5度；If the start signal output by the comparison module is earlier than the start signal of the zero-sequence voltage detection module in the existing control system, the angle control on the inverter side is directly started to increase the arc extinguishing angle by 5 degrees;
如果现有控制系统中的零序电压检测模块的启动信号先于比较模块的启动信号，则产生一个保持信号，帮助保持零序电压环节增加的熄弧角(增加的角度由零序电压环节决定)直至谐波电压含有率低于3％的启动门槛值。这是由于实际的零序电压判据启动值低，非常灵敏，因此在变压器空充励磁涌流作用期间，零序电压判据会正常启动，但由于空充电流的不对称性不能一直保持有效的输出。因而，控制模块根据比较模块的启动信号输出保持信号，则可以提供长时间的有效保持信号，使零序电压判据一直保持有效的输出。If the start signal of the zero-sequence voltage detection module in the existing control system is prior to the start signal of the comparison module, a hold signal is generated to help maintain the increased arc extinguishing angle of the zero-sequence voltage link (the increased angle is determined by the zero-sequence voltage link ) until the harmonic voltage content rate is lower than the start threshold of 3%. This is because the actual zero-sequence voltage criterion has a low start-up value and is very sensitive. Therefore, during the action of the transformer’s no-charge excitation inrush current, the zero-sequence voltage criterion will start normally, but due to the asymmetry of the no-charge current, it cannot always be effective. output. Therefore, the control module outputs the hold signal according to the start signal of the comparison module, which can provide an effective hold signal for a long time, so that the zero-sequence voltage criterion can always maintain a valid output.
下面结合实施例对本发明做进一步描述。The present invention will be further described below in conjunction with the examples.
如图3所示，为高岭背靠背换流站(逆变侧)及其附近的绥中电厂系统接线的示意图，绥中电厂共有2台1000MW机组，每台机升压变压器容量为1111MVA。图中高岭背靠背换流站采用常规的背靠背直流控制系统，并配置有换相失败预测模块CFPREV,可实现零序电压检测及α/β检测。As shown in Figure 3, it is a schematic diagram of the system wiring of Gaoling back-to-back converter station (inverter side) and its nearby Suizhong Power Plant. There are two 1000MW units in Suizhong Power Plant, and the capacity of each step-up transformer is 1111MVA. In the figure, the Gaoling back-to-back converter station adopts a conventional back-to-back DC control system, and is equipped with a commutation failure prediction module CFPREV, which can realize zero-sequence voltage detection and α/β detection.
如图4、图5所示，分别为采用本发明前后，绥中电厂一台升压变压器空充时造成高岭换流站发生换相失败的次数。图4中所示为未采用本发明时，高岭换流站发生换相失败四次；图5中采用本发明方法后，仅发生第一次换相失败。这是由于控制模块输出的保持信号，使得零序电压判据一直保持有效的输出，避免了后续的换相失败发生。As shown in Fig. 4 and Fig. 5, before and after adopting the present invention, the number of phase commutation failures in Gaoling converter station caused by a step-up transformer in Suizhong Power Plant was empty-charged. It is shown in Fig. 4 that when the present invention is not adopted, four commutation failures occurred in the Kaolin converter station; in Fig. 5, only the first commutation failure occurred after the method of the present invention was adopted. This is because the hold signal output by the control module makes the zero-sequence voltage criterion always maintain a valid output, avoiding subsequent commutation failures.
上述各实施例仅用于说明本发明，各部件的结构、尺寸、设置位置及形状都是可以有所变化的，在本发明技术方案的基础上，凡根据本发明原理对个别部件进行的改进和等同变换，均不应排除在本发明的保护范围之外。The above-mentioned embodiments are only used to illustrate the present invention, and the structure, size, location and shape of each component can be changed. On the basis of the technical solution of the present invention, all improvements to individual components according to the principles of the present invention and equivalent transformations shall not be excluded from the protection scope of the present invention.
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