Introduction to the current technical basis and characteristics of digital substations

A Brief Introduction to the Current Technical Basis and Characteristics of Digital Substation

Keywords: digital substation, technical basis, characteristics

Abstract: The continuous development of contemporary science and technology promotes the application and development of microelectronics technology and information technology in the power system.

Abstract. At the same time, the introduction of digital technology also makes changes in the operation of substations. The introduction of digital technology in substations makes the secondary equipment of substations gradually extend to the primary equipment. The digitalization process of the traditional substation makes the substation operation more automated, more scientific management, so the study of the technical basis and characteristics of the digital substation has a very great significance.

The development and application of digital technology makes the digital substation has the technical support. At present, China's digital substation technology is mainly digital electrical measurement system. The substation automation technology basis mainly includes: intelligent switch, photoelectric current and voltage transformers, primary operation of the equipment, online status detection system, operation training simulation technology. The characteristics of digital substation and the influence of technology will inevitably make the digital substation become the trend of development. This paper discusses the main technical basis and characteristics of the digital substation.

1. The technical characteristics of the digital substation

The current digital substation is mainly through the electronic transformers, intelligent switches and other digital primary equipment, networked secondary equipment layered composition, in the IEC61850 communication specifications on the basis of the gradual realization of the substation system continues to be information technology, automation, intelligent and other requirements. Intellectualization and other requirements.

First of all, the electrical equipment information in the substation through the digital technology can realize the mutual resources **** enjoy and use, so that the operation is more convenient, and at the same time reduce the number of times and time to exit the substation equipment, reduce the loss, improve the use of equipment time, for the number of automation equipment for streamlining, greatly simplify the substation's secondary wiring, and improve the use of substation equipment. The reliability of the system, maintenance and timely update to expand the function of the equipment in the substation.

Secondly, the gradual realization of the substation information in the process of its system operation and other support systems between the information **** enjoyment, reducing the duplication of resources, is conducive to the recovery of investment costs and extend the service life of the substation. Reduce the cycle of maintenance costs and construction costs. The main symbol of the digital substation is the realization of the digitalization of data collection, through the use of digital electrical measurement tools, such as photoelectric transformers, electronic transformers, etc. to collect current, voltage, etc., the collection and measurement of these electrical quantities, to achieve the effective isolation of the substation's first and second systems. As a result, the dynamic measurement range of electrical quantities in the substation is increased. At the same time, because of the digitization of the acquisition also improves the accuracy of the measurement of electrical quantities. In preparation for the realization of the substation information **** enjoy at the same time, for the previous substation device redundancy towards information redundancy provides the information base, and gradually make the substation electrical quantity collection and measurement towards informationization, integration.

Third, the distribution of substation information system appears stratified. In the past, the substation automation system is mainly centralized, while the digital substation has changed the previous centralized distributed. Digital substation through the use of the second generation of hierarchical distributed automation system can be more complete record of each device in the substation information, and timely display, greatly improving the network communication 'speed and openness.

On the basis of the IEC61850 communication specification proposed on the digital substation process layer, interval layer and station control layer and other three-layer structure model. Object-oriented modeling can be used, through software reuse, embedded and other real-time operation and control systems and other high-tech technologies, to continuously meet the digital substation and other power systems for real-time, reliability needs. Not only can it effectively solve the interoperability problem between heterogeneous systems in the substation and the system operation problems caused by different devices, but also provide powerful technical support for the current digital substation hierarchical distributed model.

2. The technical basis of digital substation

The technical basis of the current digital substation needs to support the main unconventional sensors; reliable and stable communication network; digital substation component equipment stability.

China's current digital substation construction is an inevitable trend in the application of modern science and technology. Accompanied by the research and solution of many substation technology problems, the technical basis of digital substation is becoming more and more stable. First of all, the technical basis of digital substation can be seen through the composition of digital substation equipment. The technical equipment of digital substation is mainly composed of electronic voltage and current transformers, intelligent primary equipment and networked secondary equipment.

The electronic voltage and current transformer is mainly through the Rogowski coil, resistance voltage divider, resistance-capacitance voltage divider and capacitance voltage divider, so as to replace the traditional electromagnetic current and voltage transformer. In this way, the electronic current and voltage transformer of digital substation adopts advanced electronic components and electromagnetic compatibility design, which can be more direct strategy of current and voltage information. And through and digital instrumentation and other intelligent integrated measurement devices, computer technology on the current and voltage information measurement, and digital processing makes the national power grid in the electrical equipment can be online online status monitoring and protection. The traditional substation in the conventional transformer and electronic transformer is a big difference, not only than the electronic transformer insulation complexity, and the volume is relatively large, heavy weight dynamic measurement range is relatively small; not as good as the electronic transformer can be in the operation of the power system to eradicate major power failures in the operation of the hidden dangers, to ensure that the national substation power equipment safety and personal safety.

Intelligent primary equipment is mainly based on the norms and standards of substation-related equipment, not only with the basic functions of ordinary traditional substation switchgear, but also on this basis more intelligent. In addition, the digital substation intelligent primary equipment can also be online monitoring, the use of digital interfaces and intelligent electronic switch to operate a series of advanced intelligent equipment in the substation. Therefore, the intelligent primary equipment in digital substation is the important basic equipment of digital substation, which can provide the signal circuit to be detected and the operation drive circuit to be controlled. The design of microprocessing and optoelectronic technology through computers simplifies the structure of traditional conventional electromechanical relays and control loops. At the same time, intelligent primary equipment provides the basis for digital substation technology, which facilitates substation secondary circuits by connecting to digital public **** signal networks through digital programmers. At the same time, photoelectric digital and fiber optic also replace the traditional strong analog signal and control cable. More save the substation cable consumption, reduce the footprint, shorten the digital substation commissioning cycle and electronic voltage transformer electrical distance. More importantly, through the intelligent primary equipment, digital substations in the provision of online testing at the same time, reducing human error more optimized control loop.

Finally, the secondary equipment in the substation networked. Conventional secondary equipment in the traditional substation, mainly by the relay protection devices, error-proof locking devices, measurement and control devices, etc. These networked secondary equipment can be standardized, modular computer microprocessor. Through the networked secondary equipment to tell the connection between the network communication channel, really achieve the data resources **** enjoy, high-speed information transfer.

3. Currently, China's digital substation technology

At present, China's digital substation technology is mainly digital electrical measurement system. Have a high stability of the electrical quantity measurement system for the construction of digital substation can be said to be critical. Currently, the international voltage transformer system is called non-conventional transformer, this voltage transformer and the traditional transformer used in the previous substation is very different.

In the new voltage transformer based on the electro-optical effect of the voltage transformer based on the electro-optical effect of the transformer is called optical current-voltage transformer or passive transformer, while the rest of the electronic current-voltage transformer or active transformer. As we all know, due to the linear birefringence phenomenon and the luminous intensity of the light source device will decline, light in the transmission process caused by the polarization angle changes and in different materials in the Veldt constant will also be affected by the external temperature, resulting in passive transformer measurement accuracy is not stable and other issues. The optical transformer has a better linearity, measurement accuracy, passive, not easily affected by electromagnetic interference and other advantages. China's current digital substation of the well need to use the advantages of this new type of transformer, through its principle of work to improve the stability of substation work.