An automatic switching transformer operation control method for suppressing excitation inrush current

Abstract

The invention belongs to the technical field of transformer equipment protection and operation control, and relates to a transformer operation control method with economical operation and automatic switching to suppress excitation inrush current, which can protect the operation of transformers in power transmission systems. The phase angle of the circuit breaker opening and closing voltage in the transportation system realizes the mutual cancellation of the bias magnetism and the residual magnetism, suppresses the no-load excitation inrush current of the transformer and realizes automatic switching, and adopts the feedback mechanism to increase the control accuracy and reliability of the power transportation system, so that the power The transportation system automatically tracks and adapts to the change of opening and closing time of the circuit breaker due to aging or environmental changes; its overall control process is scientific and reasonable, the technical route is simple, the hardware and software technology is mature, the operation is safe, the control performance is reliable, and the investment Less, low operating cost, easy to popularize and use.

Description

Technical field: [0001] The invention belongs to the technical field of transformer equipment protection and operation control, and relates to a transformer operation control method with economical operation, automatic switching and suppression of excitation inrush current, which can protect the operation of transformers in power transmission. Background technique: [0002] At present, the commonly used transformer backup protection measurement and control device, its protection functions mainly include three-stage fixed-time complex voltage lockout (direction) overcurrent protection, three-stage (direction) zero-sequence current protection, gap zero-sequence protection, zero-sequence voltage protection, Overload protection (on-load voltage regulation, ventilation start), composite voltage, PT disconnection alarm, liquid crystal display function and normal information and operation can be completed through keyboard and liquid crystal display, and remote control can be realize...

AI Technical Summary

Problems solved by technology

[0002] At present, the commonly used transformer backup protection measurement and control device, its protection functions mainly include three-stage fixed-time complex voltage lockout (direction) overcurrent protection, three-stage (direction) zero-sequence current protection, gap zero-sequence protection, zero-sequence voltage protection, Overload protection (on-load voltage regulation, ventilation start), composite voltage, PT disconnection alarm, liquid crystal display function and normal information and operation can be completed through keyboard and liquid crystal display, and remote control can be realized through field bus interface and automation system Communication, directly drive the tripping and closing coil of the circuit breaker through the outgoing pulse and realize the tripping and closing operation of the circuit breaker, with anti-jump circuit, control circuit breaker opening and closing function, and online setting of the outlet matrix; its main functions of measurement and control include 12 channels Remote signal opening and input collection, device remote signal displacement, accident remote signal; normal circuit breaker remote control opening and closing operation; remote measurement collection and calculation: P, Q, I (IA, IC, I2, Ia, Ib, Ic, I0, I0s), U (UA, UB, UC, UAB, UBC, UCA, U1, U2), U0, F, COSФ and other analog quantities; event SOE records; the existing technology does not have the ability to control the opening and closing of circuit breakers The ability to suppress the inrush current of no-load switching; at the same time, the automatic switching of the transformer cannot be performed based on the principle of transformer economic operation; Non-linear characteristics will generate a large amplitude excitation inrush current, which will lead to misoperation of the transformer differential protection, and at the same time cause winding deformation and reduce the life of the transformer; the excitation inrush current contains multiple harmonic components and DC components, which will reduce the power supply quality of the power system. At the same time, the high-order harmonics in the inrush current have a strong destructive effect on the sensitive power electronic devices connected to the power system; in summary, the harm of the existing transformer excitation inrush current is mainly that it can cause the relay protection device of the transformer to malfunction, The operation of the transformer fails frequently; the voltage surge generated when the short-circuit fault of the transformer outlet is removed will induce the transformer protection to malfunction, causing all the loads on each side of the transformer to be cut off; It induces "sympathetic inrush" (sympathetic inrush) in operating transformers adjacent to other B power stations and C power stations, causing a large-scale power outage; a large value of excitation inrush will cause transformers and circuit breakers to be damaged damage; induce operating overvoltage and damage electrical equipment; the DC component in the excitation inrush current causes the magnetic circuit of the current transformer to be over-magnetized, which greatly reduces the measurement accuracy and the correct action rate of the relay protection device; a large number of harmonics in the excitation inrush current have a great impact on the power grid Power quality causes serious pollution; causes grid voltage to rise or fall suddenly, affecting the normal operation of other electrical equipment

In the modern power system, there are usually two transformers as standby for each other. In order to keep the transformer in an economical operation state, the transformer should be switched according to the load. During the automatic switching process of the transformer, an excitation inrush current will be generated, especially when the load changes greatly. , In the occasions where the transformer needs to be switched frequently, the suppression of the inrush current is particularly important. In order to save operating costs and facilitate installation, the inrush current suppression module is often integrated into the system, and the hardware circuit is slightly changed to realize this function through software. However, the content disclosed by these existing technologies is still immature, and there is still a lack of further improvement and support for many software and hardware in practice.

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