Line Overvoltage Research Articles

Overvoltages due to line faults on a HWL transmission line: Corona effect and mitigation techniques

In half-wavelength (HWL) transmission lines, severe temporary overvoltages are usually observed during the occurrence of line-to-line faults in specific critical locations, and it is unrealistic to ignore the impact of the corona phenomenon. To represent the corona effect, an accurate Suliciu corona model was adopted and implemented in PSCAD software, and a new technique based on the genetic algorithm (GA) was proposed to fit the model parameters. Furthermore, the paper evaluated the performance of the overvoltage mitigation method based on the installation of two spark gaps (SGs) at strategic points to detune the resonance condition. As shown, the SGs turn the HWL line overvoltage levels similar to those observed in conventional AC lines, and the corona modelling further reduces the severity of the overvoltages.

A comparison study of grid impact of photovoltaic installations in Brazil according to Normative Resolution 482 and Federal law 14.300

This work focuses on comparing the Brazilian first distributed energy net-metering policy, instituted by Normative Resolution (NR) nº 482/2012, and the new system, instituted by Federal Law 14,300/2022. A review of the development of international distributed energy regulation is presented, along with a review of the impacts caused to distribution grids because of distributed energy systems. A set of equations is presented to compare the energy billing for consumers under the old and the new Brazilian policies. Using the indication of the amount of energy the consumers are inclined to produce to reduce their bill, the PV energy production scenarios for five different low voltage distribution grids in Brazil are simulated. The simulations indicate that an increase in the power injection into the Brazilian distribution grids could lead to transformer overload and end-of- line overvoltage. The investment cost and loss of revenues from the installation of PV systems are also compared between different regulations scenarios, showing better revenues but also greater investment required for utilities under the new regulation. One of the main conclusions is that new Brazilian policy is reducing the loss of revenue in distributed energy, however, there is a risk for misplaced investments in the distribution grid.

Research and simulation of line overvoltage in HVDC transmission system

The distribution of heavy load area and resource area is seriously unbalanced in China. HVDC transmission system project with long-distance and large capacity transmission characteristics has practical significance in today’s social development. Firstly, this paper discusses the basic knowledge of over-voltage in DC transmission system and analyzes the formation mechanism of internal overvoltage, and enumerates and analyzes the common overvoltage faults at AC side and DC side. Secondly, the electromagnetic simulation software PSCAD/EMTDC is selected to build the model, and CIGRE HVDC standard control model strategy is adopted in each module. Finally, the simulation analysis is carried out, mainly aiming at the AC bus grounding fault of converter station, and the overvoltage waveform under fault condition is recorded. The over-voltage characteristics of rectifier side and inverter side under AC bus fault of converter station are compared and analyzed, which provides reliable suggestions for overvoltage and insulation coordination in future design projects.

Modeling and Analysis of Lightning Arrester for Transmission Line Overvoltage Protection

Modeling and Analysis of Lightning Arrester for Transmission Line Overvoltage Protection

Research on Overvoltage Monitoring Technology for Transmission Lines

Overvoltage is one of the important factors that cause line tripping and equipment damage. Accurate monitoring of transmission line overvoltage is of great significance for safe operation of power grid. In this paper, a transmission line overvoltage sensor based on the principle of coupled capacitance partial voltage is designed. The high voltage arm capacitance of the sensor is the stray capacitance between the sensor metal sheet and the earth, and the low pressure arm capacitance is the coupling capacitance between the sensor metal sheet and the wire. At first, the structure characteristics and sensor principle of the sensor are described, and the parameters of the sensor are calculated. The results show that the sensor has high detection accuracy and can realize overvoltage monitoring of transmission lines.

Study on characteristics of slow‐front overvoltage of ±1100 kV UHVDC transmission lines

The ±1100 kV Zhundong–Wannan ultra high-voltage direct current (UHVDC) transmission project is under construction in China, which has the highest operating voltage in the world. The length of the UHVDC overhead transmission line is greater than 3000 km. The electromagnetic transient process caused by grounding faults might have significantly impact on the overvoltage level of DC transmission line, which is crucial for the external insulation configuration of the overhead transmission line. This paper presents a detailed electromagnetic transient simulation model for the UHVDC transmission system using an open-loop extinction angle control principle. The simulation results demonstrate that the single pole grounding fault into a bipolar system causes the most serious damage. The maximum overvoltage is 1.628 p.u. and the 2% statistic overvoltage is 1.635 p.u., while the reference value is 1122 kV. The influence of DC filters for line overvoltage is also analysed here. Furthermore, results show that adding a no gap line arrester at the midpoint of transmission line can suppress line overvoltage, while the maximum overvoltage reduces by 0.138 p.u. The results obtained provides a reference for the optimisation of the external insulation configuration.

A Comprehensive AC-Side Single-Line-to-Ground Fault Ride Through Strategy of an MMC-Based HVDC System

When a single-line-to-ground (SLG) fault occurs on the ac side of the modular multilevel converter (MMC) in an high-voltage direct-current transmission (HVDC) system, it results in the ac-side voltage sag and leads to an instantaneous reduction of the MMC power capacity. Thus, it calls for the fault ride through (FRT) strategy to coordinate two MMC stations in the HVDC system to protect the MMCs against the submodule (SM) capacitor overvoltage in case of the SLG fault. In the meantime, the HVDC system is expected to track the prefault active power as much as possible during the FRT to secure the power system stability. In this paper, a comprehensive FRT strategy is proposed, which is free of interstation communication. The proposed FRT strategy presents fast dynamic response, and it can prevent effectively the MMC SM-capacitor overvoltage and HVDC transmission line overvoltage. Moreover, the second-order voltage and current fluctuations in the HVDC transmission line caused by the grid unbalance are inherently avoided. Validity of the proposed strategy and its superiority over existing methods are demonstrated by simulation of a 200-kV, 400-MW cable-based HVDC system.

Single-ended method to accurately calculate UHV AC transmission line frequency parameters

The power frequency parameter of transmission line is the basic parameter of line over-voltage calculation. It is necessary to get the parameters of 1000kV AC double-circuit line on the same tower in order to guide the operation of the project. In this paper, a method of accurately calculating UHV transmission line parameters is proposed. The length of the line is known, the voltage and current at the head of the line are measured, and the zero sequence, positive sequence total impedance and total capacitive reactance are obtained. Based on the distribution parameters Calculation formula, the line unit capacitance, resistance and inductance parameters can be obtained. The method of this paper is compared with the simulation of transmission line parameters in ATP simulation. And Through the actual measurement of the frequency parameters of Yu-heng 1000kV transmission line, it is verified that this method is suitable for the calculation of distribution parameters of UHV transmission lines.

Wireless Energy Management System for Residential Area

The energy management system (EMS) proposed in this paper uses the communication platform of ZigBee wireless sensor network in combination with the energy parameters measurement and the control functions of safety protection and monitor, in order to achieve the objectives of energy saving, carbon reduction and safe power usage. The system structure is consisted of the intelligent outlet module, wireless transmission module and central monitor and control module. Combining with the energy monitor and safety protection software, the system can achieve seven major functions, which are energy usage monitor, energy usage control, standby power management, circuit loop energy monitor and protection control, outlet overheat protection, electric leakage protection and neutral line over-voltage protection. The system can not only reduce energy losses and improve safety protection, but also benefit for suppressing carbon emission and mitigating the effects of global warning process and climate change.

Computing responses of series compensation capacitors with MOV protection in real-time

This paper describes a method that was implemented for computing responses of series compensation capacitors with MOV protection in a real-time simulator for relay testing. The salient feature of the method is that the complete circuit is modeled as a single component. Accuracy of the method was verified through extensive comparisons against the full EMTP model. Achievement of the required speed of computation was tested through real-time simulations. The application is to transmission line overvoltage protection.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A Design Method of Damping Circuits for DC Line Overvoltage

Conditions for the design of damping circuits to prevent line overvoltage in a dc transmission system are described, and a concrete design method for the analysis of these circuits on an analog computer is suggested.