Inverter Failure Research Articles

Review of Fault-Tolerant Control for Motor Inverter Failure with Operational Quality Considered

Review of Fault-Tolerant Control for Motor Inverter Failure with Operational Quality Considered

Real-time mode of operation data analysis to catch the thread-tip denotes the failure cause of the grid-tie PV central inverter

The inverter is considered the core of the PV power plant. The inverter’s failure leads to generation loss and decreases plant availability. So, it is required to investigate a clear Root Cause Analysis (RCA) to deduce the failure causes and implement the required corrective action in addition to the preventive action to avoid more inverter failure, hereby maintaining the plant available to a certain value. This paper discusses real-time mode operation data analysis of the PV grid-connected inverter due to real central inverter incidents in Benban solar park located in Egypt.The central inverter plays an important role in the Mega-Scale PV power plant. The main function of this inverter is to convert the DC power produced by the PV modules to AC power to be injected into the utility grid by considering specific characteristics based on the grid code. The availability of any PV power plant directly depends on the healthy inverter’s operation. The more increases for the installed inverters, the less availability loss in the case of inverter partial or catastrophic failures. So, it is required to focus on the failure causes of the central inverter by implementing a technical analysis using the available operational data. The monitored data of the central inverter in the PV power plant is classified into two types. The first type is the continuous time data stored in the memory. It represents the waveforms of inverter outputs like voltage, current, frequency, …. etc. Unfortunately, in case of a catastrophic failure, the central inverter is completely charred, and the continuous time data is lost due to storage memory damage. The second type is the operation data that is recorded by the SCADA system (per one-minute interval). Hereby, the operation data is the sole data in the case of the completely charred inverter. The representation of the operational data in curves indicates symptoms that can be used for the RCA processes. The investigation outcomes include three results. The first result is detecting the signature of the IGBT thermal stress on the voltage balance of the DC link capacitor. The second result is verifying a scenario for the cause of the IGBT failure by implementing a technical mathematical model based on the detected symptoms that denote the fault signature which is considered the thread-tip for detecting the failure cause. The third result is the simulating scenario for the interpretation of a DC link capacitors explosion due to the short circuit fault that occurred due to IGBT failure. The investigation in this paper is performed based on operation data analysis of the PV grid-connected inverter (central type) due to a real incident. The analysis methodology is based on mathematical calculation for the IGBT junction temperature using the measured heatsink temperature. The study concludes that after the IGBT failure occurred, it was a short circuit for a while and closed the terminals of the DC link capacitors. So, the DC link capacitors exploded and produced heavy sparks that led to enough fire to burn the inverter container completely.

Failure Risk Assessment of Grid-Connected Inverter With Parametric Uncertainty in LCL Filter

Grid-connected inverter failure may be caused by outliers of a population of units in field operation, due to the LCL filter parameter uncertainty. This paper proposes a probabilistic framework to analyze the impact of multiple filter parameter variances due to component tolerances, operating points, and aging effects. Both robust stability and filter performance are selected as the risk of failure. The robust stability of the grid-connected inverter is quantified by the structured singular value (SSV). The total harmonic distortion (THD) of the grid current is estimated to evaluate the filter performance. A case study on a three-phase inverter is performed to verify the proposed method through Hardware-in-the-Loop (HIL) simulation and physical prototype testing.

Fault-tolerant operation of the cascaded H-bridge three-level inverter for electric vehicle application

Electric Vehicle is the future of sustainable road transport. One of the important issues with electric vehicles is their inverter failure. This paper presents a fault-tolerant technique with phase fault detection and fault removal for a three-phase cascaded H-bridge three-level inverter. The phase fault-detection and fault-removal techniques are based on the switch voltage, switch current and switching signal detection. The cascaded H-bridge three-level inverter is made fault-tolerant by using an additional H-bridge and three bidirectional IGBT switches. The logic of phase fault detection and fault removal is investigated in the MATLAB-Simulink environment and validated in OPAL RT-LAB.

Third-Harmonic Current Injection for Wear-Out Reduction in Single-Phase PV Inverters

The expansion of grid-connected photovoltaic (PV) systems over the years has been followed by concerns about the PV inverter reliability. It is well known that single-phase grid-connected PV inverter has a double-line frequency ripple in the dc-link voltage, which increases the wear-out failure probability of the dc-link capacitor and affects the overall inverter reliability. This work uses a third-harmonic current injection to attenuate the double-line frequency ripple in the dc-link capacitor voltage and to improve the PV system reliability. An analytical model capable to describe the effects of the third-harmonic current injection method in the dc-link capacitor is derived. The proposed strategy is validated by simulation and experimental results. The lifetime evaluation is developed considering a 3 kVA PV inverter and one-year mission profiles. The PV inverter failure probability considering an operation period equal to 20 years decreased in 27.17% for the adopted case study. Moreover, this strategy provides a straightforward retrofit of the current inverter technology, requiring no hardwarechanges.

다층신경망을 이용한 태양광 인버터 고장진단

In this paper, an algorithm for diagnosing and predicting solar inverter failures was studied. A multi-layer neural network failure diagnosis model that can diagnose failures using inverter failure data was designed. The data were acquired from the field, and there are 307,200 items such as watt-hour meter reading value, inverter meter reading value, meter failure status, and inverter fault status. And using this data, simulations were performed to optimize parameters, and the size and input/output, activation function, loss function, optimization function, and batch size and number of times of the neural network were determined. The final simulation was performed using the determined parameters and the failure of the inverter was diagnosed. As a result, it was confirmed that the failure of the inverter was predicted with an accuracy of up to 97 [%]. Inverter failure was predicted when the operation was completely stopped, when the error between the amount of power generation and the inverter instruction value increased, and when the efficiency of the inverter changed abruptly.

Classification of Inverter Failure by Using Big Data and Machine Learning

Classification of Inverter Failure by Using Big Data and Machine Learning

PV Panel and PV Inverter Damages Caused by Combination of Edge Delamination, Water Penetration, and High String Voltage in Moderate Climate

There exist over 2 GW of photovoltaic (PV) systems in the Czech Republic, exposed to moderate continental climate. Although there exist many PV modules defects, thanks to the generally the same production year 2009, only some of them are usual at systems installed in Czech Republic. This work shows delamination failures that are frequent in moderate climate conditions. Special account is taken into edge delamination defect and its possible propagation in modules of standard construction. Combined PV panel and PV inverter failure is caused by edge delamination with water penetration and high string voltage. The electric discharge channel is created between the string of solar panels and the grounded PV panel frames. The result of the discharge channel created because of edge delamination is inverter switch- off and few months later total destruction of the inverter because of protective relay damage. The number of combined PV panel and PV inverter failures is increasing substantially after ninth year of operation of PV panels in moderate climate. Additional sealing of the PV panel frames by transparent polysiloxane gel reduced the number of combined PV panel and PV inverter failures very substantially.

Novel Thermal Management Strategy for Improved Inverter Reliability in Electric Vehicles

Requirements for electric vehicle (EV) propulsion systems—i.e., power density, switching frequency and cost—are becoming more stringent, while high reliability also needs to be ensured to maximize a vehicle’s life-cycle. Thus, the incorporation of a thermal management strategy is convenient, as most power inverter failure mechanisms are related to excessive semiconductor junction temperatures. This paper proposes a novel thermal management strategy which smartly varies the switching frequency to keep the semiconductors’ junction temperatures low enough and consequently extend the EV life-cycle. Thanks to the proposal, the drivetrain can operate safely at maximum attainable performance limits. The proposal is validated through simulation in an advanced digital platform, considering a 75-kW in-wheel Interior Permanent Magnet Synchronous Machine (IPMSM) drive fed by an automotive Silicon Carbide (SiC) power converter.

Current Flow Analysis of PV Arrays under Voltage Mismatch Conditions and an Inverter Failure

In PV (Photovoltaic) systems, the PV array is a structure in which many PV strings are connected in parallel. The voltage mismatch between PV strings, in which PV modules are connected in a series, occurs due to a voltage decrease in some modules. In this paper, research on the electrical characteristics of PV arrays due to a voltage mismatch was conducted. Considering the voltage mismatch, experiments on partial shading, the non-uniformity of irradiance, and the failure of bypass diodes were conducted on the PV module level. It was confirmed that the open-circuit voltage greatly decreased due to the failure of bypass diodes, which is among the causes of voltage mismatch. From the simulation results at the PV array level, it can be seen that a reverse current flowed into the low-potential string, which includes PV modules, causing the failure of the bypass diodes. Measuring the reverse current at one low-potential string, it was found that, in four parallel circuits, the reverse current was 12 A. For this reason, in large PV plants, an overcurrent can flow into the fuse due to the potential difference between strings, causing an output decrease of PV plants and the burnout of fuses.

Analysis and Design of Closed-Loop Control of Electrolytic Capacitor-Less Six-Pulse DC Link Three-Phase Inverter

Three-phase inverters in uninterrupted power supply, electric vehicles, and hybrid electric vehicles use an intermediate dc-link electrolytic capacitor, which has reliability issues and is one prominent cause of inverter failure and limited life. The large volume of an electrolytic capacitor increases the size and cost of the system. Recent research on electrolytic capacitorless inverters using six-pulse modulation technique along with high-frequency power conversion has attempted to address this issue. However, closed-loop operation and control has some issues due to capacitorless dc-link. In this paper, closed-loop operation, design, and implementation of an electrolytic capacitorless inverter is presented. A proof-of-concept 1-kW hardware prototype has been built and tested in a laboratory under different loading conditions. In total, 98% rated efficiency of the inverter is obtained with total harmonic distortion within 2%. Transient results during start-up and load change are smooth, demonstrating safe operation of the inverter.

Detection of the Source of the Incipient Faults Produced by Single Phase Inverter using Feed- Forward Back-Propagation Neural Network

With the increasing usage of solar Photovoltaic (PV) system in Malaysia, the condition aspect of solar PV system especially inverter system needs to be given full attention. Detection of faults at earlier stage is very important in order to avoid the extended period of down-time caused by inverter failure. Thus, this paper aims to detect the source of the incipient faults produced by a single phase inverter of a PV system. The incipient faults were generated by modifying the pulse wave control signal. A total of 100 incipient faults and one set of normal condition waveform are collected at the output of the single phase square wave inverter. These waveforms are then used to train the feed-forward backpropagation neural network. One hidden layer feed-forward backpropagation neural network of 9 neurons was trained and MSE of 6.13 × 10-4 was obtained. It was shown that the trained feed-forward backpropagation neural network was able to detect which IGBT of the single phase square wave inverter produced the incipient faults.

Reliability estimation of photovoltaic system using Markov process and dynamic programming approach

Adoption of solar energy is still at early stage and has failed to reach expected levels because of presence of several impeding factors lying in its diffusion path. One of the major impediments in adoption of Photovoltaic (PV) systems is low efficiency due to frequent failures. With the worldwide growth of renewable energy, the importance of the aspect of the reliability and stability is getting close attention. Present study is oriented towards deriving the reliability measures of a PV system made up of three subsystems, i.e. PV array, inverter and transformer connected in series. The behaviours of Mean Time to System Failure (MTSF), availability and cost-benefit function have been analysed graphically. Present investigation reveals that inverter failure affects the performance of PV system in significant manner. To fix this issue, Dynamic Programming Approach (DPA) has been applied and 95% reliability has been achieved.

Reliability estimation of photovoltaic system using Markov process and dynamic programming approach

Adoption of solar energy is still at early stage and has failed to reach expected levels because of presence of several impeding factors lying in its diffusion path. One of the major impediments in adoption of Photovoltaic (PV) systems is low efficiency due to frequent failures. With the worldwide growth of renewable energy, the importance of the aspect of the reliability and stability is getting close attention. Present study is oriented towards deriving the reliability measures of a PV system made up of three subsystems, i.e. PV array, inverter and transformer connected in series. The behaviours of Mean Time to System Failure (MTSF), availability and cost-benefit function have been analysed graphically. Present investigation reveals that inverter failure affects the performance of PV system in significant manner. To fix this issue, Dynamic Programming Approach (DPA) has been applied and 95% reliability has been achieved.

Fault-tolerant design approach for reliable offshore multi-megawatt variable frequency converters

Inverters play a key role in realizing reliable multi-megawatt power electronic converters used in offshore applications, as their failure leads to production losses and impairs safety. The performance of high power handing semiconductor devices with high speed control capabilities and redundant configurations helps in realizing a fault-tolerant design. This paper describes the reliability modeling done for an industry standard, 3-level neutral point clamped multi-megawatt inverter, the significance of semiconductor redundancy in reducing inverter failure rates, and proposes methods for achieving static and dynamic redundancy in series connected press pack type insulated gate bipolar transistors (IGBT). It is identified that, with the multi megawatt inverter having 3+2 IGBT in each half leg with dynamic redundancy incorporated, it is possible to reduce the failure rate of the inverter from 53.8% to 15% in 5 years of continuous operation. The simulation results indicate that with dynamic redundancy, it is possible to force an untriggered press pack IGBT to short circuit in <1s, when operated with a pulse width modulation frequency of 1kHz.

On-line fault detection algorithm of a photovoltaic system using wavelet transform

The fault detection algorithm of a grid-connected photovoltaic system using wavelet transform is suggested in this paper. When the faults occur in the power conditioning system, the impact on the grid system is very risky. Therefore, it is necessary to detect faults in a short time period. When using the conventional detection method, extra hardware and sensors are required to detect the inverter failure; moreover, the disadvantage of the conventional method are its high cost and re-design problem if the inverter specification needs to be changed. Multi-level decomposition wavelet transformation is an efficient method to detect the fault location and components of the inverter. Prompt and accurate diagnostic function is possible using the normalized standard deviation of the wavelet coefficients. The proposed algorithm has simple calculation and precise diagnostic capabilities of the fault detection. A computer simulation is performed and the experimental result verifies the validity of the proposed method.

Residential load and rooftop PV generation: an Australian distribution network dataset

ABSTRACTDespite the rapid uptake of small-scale solar photovoltaic (PV) systems in recent years, public availability of generation and load data at the household level remains very limited. Moreover, such data are typically measured using bi-directional meters recording only PV generation in excess of residential load rather than recording generation and load separately. In this paper, we report a publicly available dataset consisting of load and rooftop PV generation for 300 de-identified residential customers in an Australian distribution network, with load centres covering metropolitan Sydney and surrounding regional areas. The dataset spans a 3-year period, with separately reported measurements of load and PV generation at 30-min intervals. Following a detailed description of the dataset, we identify several means by which anomalous records (e.g. due to inverter failure) are identified and excised. With the resulting ‘clean’ dataset, we identify key customer-specific and aggregated characteristics of rooftop PV generation and residential load.

Performance analysis of a 3 MWp grid connected solar photovoltaic power plant in India

Renewable energy is projected to meet a significant portion of the future energy needs of India. With solar energy, being abundantly available in most parts of the country, grid connected solar photovoltaic (SPV) power plants are assuming increasing importance. Energy fed into the grid by a solar power plant depends upon seasonal variation of the solar resource, losses due to temperature variation, system losses and losses due to condition of the grid. This paper presents performance analysis of a 3MW grid connected SPV plant located in Karnataka State, India as per International Electro-technical Commission (IEC) Standard 61724, using monitored data. Normalised technical performance parameters of the plant are evaluated for the year 2011. Inverter failure losses and grid failure losses are estimated for two years of plant operation. Daily and seasonal variations in the SPV plant output are shown using monitored data at five-minute intervals. The SPV generation in relation to load duration curve of the substation is observed. A comparison of normalised performance parameters of the plant with similar parameters of other plants is given. Annual average energy generated by the plant was 1372kWh per kWp of the installed capacity. Performance of the plant is satisfactory in comparison with that reported from other countries.

웨이블렛 변환을 이용한 태양광 발전시스템의 고장진단에 관한 연구

The fault detection technique of the grid-connected photovoltaic system using wavelet transform has been suggested in this paper. The additional hardware and sensors are required to detect the inverter failure in the conventional method, and it has the disadvantage of high cost and re-design problem if the inverter specification has been changed. The suggested method used the inverter voltage and current waveform to detect the failure and the location by the wavelet coefficients variations. The prompt and accurate diagnostic function is possible using the normalized standard deviation method. The merit of the proposed method is the simple calculation and precise diagnostic capabilities of the fault detection. The computer simulation is performed and the experimental result verifies the validity of the proposed method.

Transistor Diagnostic Strategies and Extended Operation Under One-Transistor Trigger Suppression in Inverter Power Drives

A fault-accommodation technique proposed for inverter drive systems extends the operation of an electrical power drive during an incipient power transistor fault. The discussed technique utilizes diagnostic methods to identify and isolate degraded power transistors. Once isolated, an appropriate fault-accommodating control method using one-transistor trigger suppression control relieves electrical overstress being applied to the degraded transistor to maintain motor operation, thus avoiding an inverter failure. Simulations and experimental tests demonstrate the feasibility of the proposed method for motor start-up even with a suboptimal control technique of constant V/f type. Also discussed are advantages and potential drawbacks of this technique.