The problem lies in the frequent breakdown of high voltage equipment due to insulation failures, mainly caused by Partial Discharges (PD). Studying PD requires expensive high voltage laboratories and specialized equipment, making it inaccessible to new researchers. Current PD detection methods rely on fixed patterns for pulse generation, limiting their accuracy in real-world conditions. Moreover, calibration of detection equipment is challenging and requires frequent validation. There's a need for a solution that simplifies PD research, improves detection accuracy, and enhances the reliability of electrical systems by accurately simulating and studying PD under various conditions.
Figure 1: Block Diagram of the Universal Partial Discharge Hardware Simulator
Figure 2: Screenshot of the computer based Human Machine Interface (HMI)
The Universal Hardware PD Simulator addresses the critical issue of insulation breakdown in high voltage equipment, a concern in the power system industry. Partial Discharges (PD) precede such breakdowns, indicating insulation deterioration. Existing methods for studying PD require costly high voltage labs and complex equipment, posing barriers to new researchers. This simulator bridges this gap by generating PD pulses using physics-based models, enabling calibration and testing of detection equipment. It employs a user-friendly interface to configure test parameters and utilizes advanced hardware for high-fidelity pulse generation. This innovation supports research, enhances calibration accuracy, and aids in predicting insulation health, ensuring reliable operation of electrical systems.
- High Resolution Fast Settling DAC Based Implementation: Ensures generation of precise analog pulses with microsecond-level time resolution, critical for accurate calibration and testing of PD detection equipment.
- Physics-Based Formulations for Pulse Generation: Derives pulse characteristics from theoretical models, enhancing simulation accuracy and supporting advanced research in insulation health diagnostics.
- Flexible Hardware and Software Schemes: Allows seamless adaptation to evolving PD detection methodologies and future research insights, ensuring long-term usability and relevance.
- Analog Electronics-Based Pulse Generation System: Capable of producing pulses with variable magnitudes and customizable rise and fall times, providing versatility in testing and calibration scenarios.
- Scalable Graphical User Interface (GUI): Supports intuitive configuration of test parameters for different dielectric materials, defect types, and electrode configurations, facilitating easy experimentation and data collection.
- Integration of Stochastic PD Pulse Characteristics: Incorporates randomness in pulse intervals, replicating real-world PD conditions accurately for robust testing and validation purposes.
- Enhanced Pulse Resolution and Signal Fidelity: Delivers high fidelity output through a 16-bit DAC and advanced analog circuitry, ensuring reliable and precise pulse generation for critical PD detection applications.
Design of Partial Discharge Emulator
Fig. 1. shows the block diagram of the software-hardware integrated PD emulator which has been designed, construction, tested and validated as a part of this work. Fig. 2 shows the block diagram of the entire system setup with the actual picture of the designed interfacing hardware.
The system consists of three main blocks 1. Software block 2. Buffer circuit 3. Analog pulse generation circuit. The software block of the system executes in two steps; in the first step, the data entry pertaining to void/ defect and insulation are made. In the second step, the characteristics data is used to calculate the parameters associated with PD pulses based on Pederson’s model. The software design ensures that PD statistical characteristics are obtained. A USB based data transfer between the PC and the analog circuit is implemented using an MCU based system. The pulses data obtained is stored in the buffer circuit before being sequentially fed to the analog pulse generation circuit.
The data buffer serves a dual purpose, as it can be used to store data obtained from measurements. The third block of the proposed system is the analog pulse generation circuit. A specially designed analog precision circuit is designed and implemented to generate narrow pulses with desired amplitudes with varying time between pulses. The design of this pulse generation circuit is done based on the desired specifications of the PD pulses obtained during different stages of ageing. Based on the analysis of the pulses during different stages of ageing, it is concluded that the pulse generation circuit should be capable of producing pulses with magnitude in the range of a few hundreds of μV to hundreds of mV. The minimum rise and fall times required to be produced by the hardware circuit are 1 − 3 ns and 10 ns, respectively.
Similarly, the maximum rise and fall times are 500 ns and 1 μs, respectively. The maximum repetition frequency is 10 MHz. A high repetition rate of PD implies that the failure of the insulator is imminent. At this stage, the rise and fall times and pulse width, i.e. pulse shape characteristics, are not essential parameters for health diagnosis of the insulation. Hence the system has been designed to generate pulses with a maximum repetition rate of 100 kHz, beyond which only a high repetition rate is an adequate indication of deteriorating insulation condition.
Thus, the specifications required to replicate the PDs as seen on the field are:
- Range of amplitude: few hundreds of μV to hundreds of mV
- Minimum rise times: 3 ns
- Maximum repetition rate: 100 kHz The analog precision pulse generator designed can generate narrow pulses (i.e. with rise times as low as ∼ 4 ns and amplitudes with 16-bit accuracy) with PD pulse attributes generated by the software physics backed algorithm.
- The Universal Partial Discharge Emulator has been designed, developed, constructed and validated. It comprises of a Partial Discharge (PD) physics-based software simulation and hardware pulse generation circuit to produce desired analog pulses based on the PD Attributes.
- LabVIEW software-based HMI and physics backed algorithm, which generates the PD characteristics as seen in various stages of ageing using formulations based on Pedersons induced charge theory. The model also incorporates the stochastic nature of the PD pulses.
- The specially designed analog precision pulse generator can generate narrow pulses (i.e. with rise times as low as ∼ 4 ns and amplitudes with 16-bit accuracy) with PD pulse attributes generated by the software physics backed algorithm. These pulses which replicate the actual PD can be displayed on an oscilloscope for training and research purposes.
- The calibration system for PD measuring instruments using a PD emulator has also been designed and simulated.
- The results of the PD Simulator match well with those experimentally reported in literature. The hardware analog electronic circuit has been constructed and validated to generate bipolar pulses with rise times as low as ∼30 ns and amplitude in range of few μV to hundreds of mV with 16-bit accuracy. The designed system can reproduce amplitudes changes with an accuracy of ± 1 LSB. The time interval between pulses that can be generated using this circuit ranges from 10 μs to 1 s with as low as 0.8% error in most of the range of operation. An enhanced scheme was designed, developed and simulated to generate fast rising pulses with facility of digitally adjustable rise time, and digitally adjustable pulse width. This scheme was implemented in Multisim and the pulse shapes were observed on the oscilloscope in the simulation. The minimum rise time of 3.85 ns, has been achieved with this enhanced design. This research grade emulator system designed and constructed is flexible and scalable.
- The developed software can be used to generate knowledge for non-standard cases which are usually difficult to experiment with. It may be worth noting that, the physical processes (field calculations, electron generation, determination of number of charged particles, and probability of PD occurrence) in the PD mechanism have been incorporated in the software. Hence, there is a high probability that a new case also can get correctly diagnosed.
- In the case of surface phenomena, weights are adjusted suitably to calculate the amount of surface charges so as to reproduce the observed PRPD patterns and the rise time values.
- The versatility of the designed system is verified by simulating three different cases in which PD could occur.
- The designed hardware analog pulse generation system is also flexible such that any advances in the mathematical formulation can be adopted by the system to generate the PD pulses and its attributes satisfying the new phenomenon. The specifications required to replicate the PDs as seen in the field was compared with the designed hardware analog pulse generation system and found to be satisfactory.
- The PD pulses observed at the various stages of ageing in the insulation of the equipment, from the time of putting in service to above 100 hours of service-can be studied by the researchers using this PD Emulator.
- The LabVIEW tool developed for prediction of stage of ageing of the insulation confirms that using the PRPD patterns along with the time resolved data and its statistics from frequency, time-frequency and time domain analysis can be used efficiently for classification of the PD as per ageing.
- Facilitates safer and more reliable operation of high voltage equipment, reducing unexpected failures and enhancing overall system reliability.
- Promotes cost-efficiency in power system maintenance and operations through improved diagnostic capabilities.
- Enhances safety standards in high voltage laboratories by minimizing risks associated with experimental procedures.
- Contributes to environmental conservation efforts by optimizing energy consumption and reducing waste associated with equipment failures.
Power Systems, Energy Sector, Calibration and Testing
Power Systems, Energy Infrastructure, High Voltage Laboratories, PD Detection, Calibration and Testing
201621029072
491883