First, the substation
Substation, the place where the voltage is changed. In order to transport the power from the power plant to a remote place, the voltage must be increased to become a high-voltage power, and the voltage should be lowered as needed near the user. The operation of the lifting voltage is completed by the substation, the main equipment. It is a switch and a transformer. A substation is a power facility that converts voltage, receives and distributes electrical energy, controls the flow of electrical power, and adjusts voltage in a power system. It connects the voltages of the various levels of voltage through its transformer.
Second, substation classification
Substations can have many different classifications depending on different attributes.
1. According to the status and role of the substation in the power system can be divided into four categories, as shown in Figure-1.
(1) Hub substation
Located at the pivot point of the power system, the voltage level is generally 220kV, 330kV (Northwest Power Grid only) and 500kV. It is connected with multiple power sources, and there are many outlet circuits, forming a ring network, and the power capacity is large. After the power failure of the whole station, the power will be cut off or the system will be large. Dissociated, so it plays an important role in the stability and reliability of the power system.
(2) Intermediate substation
It is located at the interface of the main trunk circuit of the system or the main trunk of the system. The voltage level is generally 330-220KV, and 2 to 3 power supplies and several lines are collected. The high-voltage side is mainly through the power, and the voltage is reduced to supply power to the local users.
(3) Regional substation
The regional substation is a major substation in a region and a small and medium-sized city. The secondary substation in the region is powered by a substation in the region and directly supplies power to the region. The voltage level is generally 220KV, which will cause power supply to the region or city after the power outage. Disorder.
(4) Terminal substation
It is located at the terminal of the distribution line, close to the load, and the 10~110KV lead-in line on the high-voltage side, after the step-down, supplies power to the user.
figure 1
2. Divided into 2 categories according to the function of the transformer:
(1) Boost substation
A boost substation is a substation that turns a low voltage into a high voltage. For example, in a power plant, it is necessary to raise the generator outlet voltage to the system voltage, that is, a boost substation.
(2) Step-down substation
In contrast to booster substations, substations that turn high voltages into low voltages, most of which are step-down substations in power systems.
3. Divided into 2 categories according to the duty mode:
(1) Manned substation
Most large-capacity and important substations use manned substations.
(2) Unattended substation
The measurement monitoring and control operations of the unattended substation are remotely controlled by the dispatch center, and no personnel are on duty in the substation.
4. Divided into 2 categories according to the internal implementation principle:
(1) Traditional substation
The traditional substation is based on the conventional electromagnetic and capacitive transformer (TA/TV). The secondary equipment mostly relies on enough cables, and then uses the empty contacts to exchange information with the analog signal as the carrier. Substation. In this type of substation, the equipment is relatively independent, lacking overall coordination and function optimization, input information cannot be shared, wiring is complicated, and system expansion is difficult.
(2) Digital substation
Digital substation is built by intelligent primary equipment (electronic transformer, intelligent switch, etc.) and networked secondary equipment layer (process layer, bay level, station control layer), based on IEC61850 communication specification, capable of A modern substation that realizes the digitalization of transmission and processing information of substation and information sharing and interoperability between intelligent electrical equipment in the station.
figure 2
Third, the development trend of substations
In recent years, with the continuous advancement of digital technology and the promotion and application of IEC61850 standard in China, the digital substation based on IEC61850 has become the standard for new substations in China. According to the analysis report in the industry, there are thousands of 35 kV and above. The new substation will be put into operation; the traditional substation will also be gradually updated and will be replaced.
Digital substation has important features such as total station information digitization, communication platform networking, information sharing standardization, and advanced application interaction. At the same time, digital substation has a great impact on the electrical equipment industry, which will lead to secondary equipment industry, transformer industry and even switch industry. Reshuffle and use IEC61850 as a link to promote mutual cooperation and penetration of primary and secondary equipment companies.
The DT6000 series intelligent substation optical digital tester developed by Zhou Ligong Zhiyuan Electronics is a portable handheld tester based on IEC61850, which has network communication protocols (IEC61850-9-1, IEC61850-9-2, for the process layer and the spacer layer of the intelligent substation. IEC60044-7/8, GOOSE, IEEE1588) perform real-time analysis and monitoring, and analyze the telemetry remote signal data transmitted therein, and also have various functions such as protection test and oscillography analysis. It displays the analysis results in an intuitive way: such as the effective value of voltage and current, phase angle, harmonics, power and other electrical energy analysis; switching state and action time analysis; time synchronization analysis; optical power analysis of optical signals, The necessary tools for routine maintenance, inspection, and commissioning of the substation process and the operation of the interval layer equipment, Figure-3 is the field test using the DT6000S.
image 3
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