Lightning Arrester Online Monitoring System (Winfoss-M7)

Product Overview

With the comprehensive implementation of condition-based maintenance for high-voltage equipment, it is essential to establish a real-time monitoring system for the operating status of capacitive equipment and lightning arresters. This system provides technical support for the condition evaluation, risk analysis, fault diagnosis, and maintenance strategy decision-making of capacitive equipment and lightning arresters. In view of the above reasons, both the State Grid Corporation and the China Southern Power Grid have issued clear requirements for the implementation of condition-based online monitoring of capacitive equipment and lightning arresters, and have also set clear technical specifications for the monitoring devices used in the monitoring systems.

To meet the deployment requirements of the State Grid Corporation and the China Southern Power Grid, our company's R&D team for high-voltage equipment condition online monitoring, in collaboration with experts and professors from Huazhong University of Science and Technology, has developed the M7 type lightning arrester insulation condition online monitoring system, which is at the domestic leading level, based on our company's many years of practical experience in high-voltage equipment condition online monitoring.

Technical Principles

The lightning arrester (MOA) is mainly composed of highly nonlinear zinc oxide resistor discs, and it does not have a series spark gap. Therefore, when operating under power frequency voltage, for zinc oxide arresters of 110–150 kV, approximately 0.5–4.5 mA of current flows through the resistor discs. Under the long-term effect of this current, the resistor disc material will gradually age. Consequently, the current flowing through the resistor discs will gradually increase. The total current flowing through the resistor discs mainly consists of resistive current and capacitive current. The capacitive current remains constant within the designed service life. Therefore, the change in the total current can be approximately regarded as an increase in the amplitude of the active component of the current. The WINFOSS-M7 is based on the above characteristics and uses the fundamental wave method to measure the current of the zinc oxide arrester to dynamically monitor the working condition of the arrester in real time.

Synchronously sample the voltage, frequency of the busbar where the capacitive equipment and lightning arrester are located, and the current on the grounding lines of the capacitive equipment and lightning arrester. Special algorithms are used to calculate the angle between the current and voltage, as well as the components of resistive current and capacitive current in the leakage current of the capacitive equipment and lightning arrester. The capacitance and dielectric loss of the capacitive equipment are calculated based on the relationship between the current and voltage angles.

Product Features

○High-precision single-turn core-through sensor

The sampling sensor uses a high-permeability glass-molybdenum alloy core, deep negative feedback compensation technology, optimized amplification circuit, and effective three-layer shielding design. This effectively reduces the absolute phase error and phase drift caused by temperature changes (within the temperature range of -40℃ to +70℃, the phase measurement error is within 2′). The monitoring sensor uses a single-turn core-through sampling method, which does not change the original grounding method of the high-voltage equipment, ensuring the safety of the monitored high-voltage equipment.

○LCU Fully digital, integrated local monitoring unit (LCU)

The monitoring unit is designed as an integrated module, with the monitoring module and sampling sensors all concentrated in one unit. This enables local sampling, measurement, calculation, and digital transmission of the monitoring signals.

The monitoring unit's CPU uses a high-speed industrial-grade 32-bit ARM microprocessor, which meets the demands for large-scale data computation on site. The signal processing employs advanced programmable amplification technology, and the analog-to-digital conversion utilizes a 16-bit high-speed A/D converter, ensuring high-precision measurement of minute signals.

The monitoring unit is equipped with flexible communication interfaces that can meet the integration needs of various projects.

○Superior Electromagnetic Interference Resistance

The monitoring unit and sensor adopt an integrated design. The unit's casing is made of aluminum, which can effectively prevent interference from external electric fields. The internal sensor is housed in a 5mm thick steel casing, which can effectively guard against the influence of external electric and magnetic fields on the sensor. The anti-interference capability of the monitoring unit has passed the rigorous tests conducted by national authoritative departments.

○The leading method for calculating dielectric loss

The monitoring unit employs a proprietary algorithm that has been field-verified, effectively addressing the impact of various interferences such as on-site frequency fluctuations and power grid harmonics on dielectric loss measurement, ensuring the accuracy and stability of dielectric loss parameter measurement.

○Stable and Reliable Synchronization Technology

The system features a unique synchronization technology. The monitoring unit is designed with a reliable and fast synchronization signal recognition circuit, ensuring that the sampling time difference between each independent monitoring unit does not exceed 1us. The synchronization port of the monitoring unit has been designed to be surge-resistant, lightning-proof, and filtered, guaranteeing stable and reliable operation.

○Innovative Appearance Design

The monitoring unit adopts an integrated design, with an aesthetically pleasing and novel structure, and flexible installation options. The housing design of the monitoring unit not only meets the requirements for different equipment shield grounding wire穿芯 demands on site, but also ensures the need for its own operational heat dissipation. The monitoring unit is designed to be waterproof and dustproof, with a protection rating of IP65, meeting the special protection requirements for outdoor operating equipment.

○Truly Hierarchical and Distributed System Structure

A hierarchical and distributed system structure is adopted. The monitoring unit (LCU) is installed locally according to the distribution of high-voltage equipment on site, performs local digital measurement, and communicates with the local monitoring substation via a fieldbus. The monitoring substation at the bay level has flexible IED interfaces, fully meeting the needs of traditional substation retrofitting and new digital substation construction. The system has a simple on-site layout structure, with minimal construction and maintenance workload; it is highly compatible and easily expandable.

○Optimized System Design

The system has achieved miniaturization, integration, digitalization, intelligence, networking, and specialization of the monitoring devices.

Technical Parameters

Technical Parameters of the Lightning Arrester Monitoring Unit:

n  Full current measurement range: 100uA - 700mA

n  Measurement accuracy: ±(5% of reading + 5uA)

n  Resistive current measurement range: 10uA - 700mA

n  Measurement accuracy: ±(5% of reading + 5uA)

n  Capacitive current measurement range: 10uA - 700mA

n  Measurement accuracy: ±(5% of reading + 5uA)

Technical Parameters for Voltage Monitoring:

n  System voltage measurement range: 35kV–1000kV

n  Measurement accuracy: ±0.2% of reading

n  System frequency measurement range: 47.5–52.5Hz

n  Measurement accuracy: ±0.002Hz

Environmental Conditions:

n  Ambient temperature: -40℃ to +70℃

n  Relative humidity: 0–98%

n  Atmospheric pressure: 86–106kPa

n  Power supply: AC 220V±20% 50Hz

n  Power consumption of lightning arrester monitoring unit:<20VA

Standard Configuration

 Product Name          Specification Model             Quantity

n  Lightning Arrester Insulation Online Monitoring IED WFS-M7-IED 1 unit

n  Core-through zero-flux lightning arrester monitoring device WFS-M7-DL 1 unit per phase of lightning arrester

n  Precision voltage sampling device WFS-M7-DY 1 unit (capable of monitoring 3 phases)

n  Intelligent terminal box WFS-M7-ZD 1 unit per voltage level

n  Switch WFS-M7-JH 1 unit (optional)

n  Control cabinet 2200 控制800600 (mm) 1 unit (optional)

n  Power cable RVP22--4×2×1 Several

n  Signal cable RV22--3×1.5 Several

n  User manual 1 set

n  Factory inspection report and other user documents 1 set

Service Guarantee

l  Provide on-site installation, commissioning, and training guidance, and conduct on-site demonstration operations.

l  Provide detailed Chinese instruction manuals and user guides.

l  One-year free warranty, lifetime spare parts support, and maintenance.

l  24/7 hotline available 365 days a year to answer user inquiries.