Zaɓi na Gargajiya na Ƙarfin Kula da Kula da Maimaita Masu Amfani a Cikin IEE-Business
A UHV GIS na, current transformers suna da muhimmanci wajen kudin kwarewa mai zurfi. Zanubin da suka shafi yana haɓaka masu gurbin kwarewa, don haka, ya kamata bayyana abin daɗi a kan gwamnati JJG1021 - 2007 a cikin gwamnati. A cikin gwamnati, amfani da sursuri, voltage regulators, da kuma current boosters. Saboda ci gaba a cikin GIS, bincike circuits da ke nuna grounding knives, bushings, da kuma return conductors; circuits masu daidai sun taimaka waɗanda suke saƙo da kuma zama daidai.
Kadan da ƙarfin gwamnati mai yawa, circuits mai tsawo, da kuma high impedance, amma reactive compensation (da amfani da inductive reactance mai yawa a cikin GIS primary circuits) yana ƙara bukatar da zaɓuɓɓuka na ƙarfin. Zanubin da shi daidai na primary circuit parameter yana da muhimmanci. Amfani da hanyoyin da ake amfani a baya ba su daidai ma su Iya amfani a cikin GIS primary circuits, don haka, wannan paper: yanayi UHV GIS current transformer primary circuit structures/features don zabi verification circuits; yin hanyoyin intelligent don samun zanubin da shi daidai da kuma automation.
1 Primary Circuit Selection for UHV GIS Current Transformers
1.1 Structure & Features
GIS tana da substation primary equipment (saboda transformers) a cikin hanyoyi biyu (misali, CB, DS). Ci gaba a cikin metal shells, GIS tana ba: miniaturization (tare da SF6), karshen kasa); high reliability (sealed live parts suna da inganci a tsakanin environment/earthquakes); safety (babu electric shock/fire risks); superior performance (shields EM/static, babu interference); short installation (factory assembly cuts on - site time); easy maintenance & long inspection (good structure, advanced arc extinction).
1.2 Circuit Selection
Circuit breakers suna nan a kan makwabta GIS pipelines, tare da current transformers a duk biyu. Disconnectors suna nan a kan bari, tare da grounding switches don protection. Pipelines sun amfani da (SF6), da kuma transformers suna da epoxy resin semi - casting. Saboda ci gaba, amfani da exposed grounding switches/bushings + return conductors. Ana da hanyoyi biyar: grounding switches a kan ends na breaker, GIS pipeline shells, large - current conductors, ko adjacent GIS busbars as return. Ba da hanyar reactive compensation, adjacent GIS busbars (safe, simple, operable) suna zaba don bayyana a cikin gwamnati.
2 Research on GIS Primary Circuit Intelligent Measurement Systems
2.1 Parameter Measurement Method Analysis
GIS primary circuits suna da equivalent resistance R da inductive reactance (ZL). Hanyoyin da ake amfani a baya (measure R, apply AC, calculate complex impedance Z then (ZL) sun bukatar manya devices, ops mai tsawo, da kuma heavy calculations. Wannan paper tana yin hanyoyin intelligent. Key tasks: system design (component matching, process planning); determine signal collection (points, methods, circuits for voltage/current); find voltage - current phase difference calculation; select line parameter methods (from amplitude/phase difference, get equivalent resistance/inductive reactance); overcome harmonics/interference for accuracy.
2.2 Overall Design of the Intelligent Measurement System
The intelligent measurement system centers around a microcontroller - based computer system, equipped with buttons, a display, a printer, and other peripherals. The voltage and current signals are captured by the signal acquisition system, then processed through a filter, multiplexer switch, automatic signal gain amplifier, and analog - to - digital (A/D) converter before reaching the microcontroller for signal processing. The hardware principle is illustrated in Figure 1.
System Components
Operational Process
The acquired signals are processed and transmitted to the microcontroller, which runs pre - installed signal processing programs. The system analyzes the data via dedicated software, computes the results, and displays them on the screen.
2.3 Design of the Signal Acquisition Circuit
Given that measuring primary circuit parameters doesn’t require high currents, the system uses a regulated power supply with a 200A output. After passing through a current booster, the induced current on the line side is significantly lower than the GIS rated current, minimizing the need for large - capacity equipment. This setup keeps the current within the safe operating range of the GIS enclosure and grounding switches.
Circuit Options
The signal acquisition circuit can adopt any of the three test circuits discussed earlier (excluding the grounding - switch - based circuit, which doesn’t cover the entire GIS line). Using multiple methods simultaneously can enhance measurement accuracy. During testing, voltage and current transformers are installed to convert high primary - side values into manageable secondary - side signals for the acquisition system.
Circuit Design for Adjacent GIS Busbar Return Conductor
When using an adjacent GIS high - current busbar as the return conductor:
The designed signal acquisition circuit is shown in Figure 2. The collected voltage and current data correspond to the total values of the circuit.
2.4 Selection of Calculation Method for Voltage and Current Phase Difference
This measurement system uses the zero - crossing phase angle method to measure the phase difference between voltage and current. The so - called zero - crossing phase angle method is to shape the fundamental wave components of the collected voltage and current signals into square waves, obtain their respective zero - crossing pulses through a differential circuit, measure the time difference between the two pulses, and then calculate the phase difference between the voltage and current.
Assume that the time of the rising edge of the voltage square wave is τ1 and the time of the rising edge of the current square wave is τ2. Then, the calculation formula for the phase difference φ between the two signals is as follows:
Among them: T is the period of voltage and current. Since the frequency of voltage and current is 50 Hz, its period is 0.02 s. The calculation formula for the phase difference of voltage and current can be simplified as：
2.5 Calculation Method for Line Parameters
These calculation processes have been programmed into the microcontroller's memory. Specialized signal - processing software is used to automatically handle the data, and the results are displayed on the device's monitor. For the convenience of analysis, the voltage and current mentioned below are by default considered to have been converted to the voltage and current of the primary side.
Assume that the amplitude of the total line voltage collected by the signal acquisition system is U, and the amplitude of the line current is I. Then, the total line resistance R1 and inductance L1 can be obtained from the following formulas
If the resistivity of the connecting conductor between the busbars of the GIS outgoing line bushing is measured as ρ, the effective cross - sectional area is s, and the length of the conductor is measured as l, then the impedance calculation formula for this connecting conductor is as follows
Neglecting other connecting conductors, the equivalent resistance R and equivalent inductance L of the primary circuit of the GIS pipeline can be obtained from the following formulas.
Error Control & Optimization
Each measurement method should be repeated 3 times at different intervals to reduce errors. If feasible, use all 3 methods simultaneously and compare results:
To mitigate interference and harmonics:
3. Conclusion
UHV GIS tana da substation primary equipment a cikin metal tanks, tana ba immunity zuwa environmental factors, high reliability, da kuma minimal footprint. Don bayyana current transformer, amfani da adjacent GIS busbars as return conductors tana saƙo wiring da kuma ensures safety, making it ideal for primary detection circuits.
Wannan study tana bayyana intelligent measurement system don GIS primary circuits, tana iya samun zanubin da shi daidai da kuma inductance. The system's user - friendly interface, high accuracy, and robust anti - interference capabilities advance automation in GIS verification. Further field testing is recommended for validation and refinement.
