In an energy storage system, the voltage level on the DC bus side is usually higher, while the voltage level on the battery side is lower with a wide variation range. Under this background, a three-level bidirectional full-bridge multi-resonant DC-DC converter topology is proposed, in which a three-level structure is adopted on the high-voltage side to reduce the voltage stress of the switch. The resonant cavity is designed as an LLCLC multi-resonant structure with auxiliary inductance, so that the left and right sides of the equivalent circuit is symmetrical, thus realizing the peer-to-peer driving control of forward and reverse operations and the bidirectional transmission of power. An improved synchronous pulse-frequency-modulation control strategy is adopted, so that the full-range zero-voltage-switch can be realized for switches on the high- and low-voltage side regardless of the forward or reverse operation. Compared with the traditional LLC resonant topologies, the proposed topology can achieve a wider range of voltage gain in a narrower frequency range. Through the optimization design of resonant cavity parameters, the converter can transmit the current fundamental wave and third harmonic power at the same time, thereby improving the energy transmission efficiency. Finally, a 2 kW experimental prototype was built, and experimental results verified the theoretical analysis.

The bi-directional power transmission with a high efficiency and a high power density can be achieved by employing CLLC resonant converters. However, the traditional parameter design method is cumbersome and requires multiple iterations to obtain appropriate circuit parameters. To solve this problem, the working principle and characteristics of a bi-directional CLLC converter are analyzed, and a novel parameter design method is proposed. By considering the full range of soft switching, design index constraints and high-efficiency optimization conditions, the range of design parameters is narrowed and the design steps are optimized, thus effectively reducing the complexity of the converter parameter design process. Based on the demand for a 48~380 V/kW bi-directional DC-DC converter in industrial applications, specific parameter design steps and results were given, and a prototype was developed. The correctness and effectiveness of the proposed parameter design method was verified through experimental testing.

Aimed at the problems of a traditional LLC resonant converter in wide voltage applications such as a wide switching frequency range and a poor voltage regulation performance, a voltage doubling two-phase parallel resonant converter is proposed. There is a parallel double half-bridge LLC structure on the primary side of this converter, and a bidirectional switch is introduced into the full-bridge rectifier network on its secondary side to form a reconfigurable voltage doubling rectifier network. Fixed frequency control is adopted during operation. The lower half-bridge on the primary side changes the input voltage of the resonant tank by changing the duty cycle, while the upper half-bridge works with a fixed duty cycle. The rectifier network on the secondary side realizes full-bridge and voltage doubling hybrid rectification under the bidirectional switch, which can achieve 4 times of voltage gain. At the same time, this converter has a good soft switching performance, its voltage gain is independent of magnetizing inductance and load, and a larger magnetizing inductance can be selected to reduce the switch-off loss and conduction loss. Finally, the feasibility of the proposed converter was verified by simulation and experimental results.

Phase-shifted full-bridge zero-voltage zero-current switching(ZVZCS) converters are favored in high- power DC conversion applications owing to their advantages such as simple structures and high efficiency. However, high-power phase-shifted full-bridge ZVZCS converters still face problems including difficulty in the current reset and severe duty cycle loss. In response to the above issues, a novel phase-shifted full-bridge ZVZCS converter is put forward, which ensures that it can realize zero-current switching over a wide load range by introducing an auxiliary circuit on the primary side to reset the current to zero before the turn-on of lagging-leg switches. At the same time, it can accelerate the commutation speed on the primary side, reduce the duty cycle loss and realize an optimized design of power supply. Based on the analysis of the circuit structure, working principle and characteristics of the proposed converter, a 1 kW experimental prototype was designed to verify its correctness.

The magnetic integrated coupling technology is introduced into a high-gain converter, and a magnetic integrated Boost converter based on diode clamping is proposed. Through the theoretical analysis of the working principle and performance characteristics of the proposed converter, it is shown that this converter can reduce its volume and inductance current ripple based on the advantages of the original converter, such as a high voltage gain and a simple control strategy. In addition, the voltage gain of the novel converter is further improved by using the switched capacitor technology, the voltage stress of the switch and diode is further reduced, and the energy conversion efficiency of the converter is effectively improved. Finally, the findings were verified by simulation and experimental results.

The constant-current power supply system is suitable for remote seabed power supply in a harsh environment owing to its strong anti-failure capability. As all the seabed equipment adopts constant-voltage power supply, a constant-current to constant-voltage conversion device is needed to convert constant-current input into constant-voltage output to provide electric energy for the seabed equipment. To solve the problem that an efficient conversion from constant-current to constant-voltage in a wide load range as well as a high-pressure isolation control, a constant-current to constant-voltage converter topology with cascade of a shunt regulator circuit and a DC transformer is proposed to achieve the efficient conversion from constant-current to constant-voltage in a wide range. Aimed at the output control problem under high-pressure isolation, an indirect control strategy for output voltage based on input-side detection is studied to achieve an accurate control of output voltage without the need of high-cost and large-volume output isolation detection devices. Finally, an experimental prototype with input of 1 A and rated power of 500 W was built to verify the feasibility of the power conversion technology of constant-current to constant-voltage converter.

Single-phase charging systems usually face the problem of secondary power pulsation. To solve this problem, a single-phase electric drive reconstructed onboard charger (EDROC) system with low voltage ripple is proposed, in which a Buck/Boost active filter is placed in parallel on the output side of a traditional single-phase EDROC system to absorb or compensate the secondary power pulsation, thereby obviously reducing the output voltage ripple of the charging system. First, the topology, working principle and secondary power pulsation generation mechanism of the single-phase EDROC system are analyzed. Second, a single-phase EDROC system with low voltage ripple is put forward by combing the Buck/Boost active filter. Meanwhile, the topology, working principle, and selection of inductors and capacitors of the Buck/Boost active filter are analyzed in detail. Third, a control strategy for the proposed EDROC system is designed. Finally, a 200 W experimental prototype was designed, and experimental results verified the feasibility of the proposed charger.

For a hybrid cascade H-bridge inverter with a DC-side voltage ratio of 1:1:2, if the hybrid carrier disp-osition modulation strategy is adopted, the problem of output power imbalance in the low-voltage unit will occur al-though there is no current backflow phenomenon and the harmonic performance of output voltage is good. To solve this problem, the power imbalance is analyzed at first. Then, an improved hybrid modulation strategy is proposed, under which the high-voltage unit performs step wave modulation and the low-voltage unit performs PWM, and two low-voltage units adopt different processing methods for the modulation wave. The good harmonic performance of output voltage is kept, the number of triangular carriers is reduced, and the control process is simplified, with a frequency doubling effect. Third, this strategy is optimized, and the switching signal of low-voltage unit is logically calculated, which can solve the power imbalance problem of low-voltage unit in two carrier cycles. Finally, the feasibility was proved by simulation and experimental results.

Aimed at the problems of current unobservable area and zero drift error in the traditional space vector pulse width modulation with single-sensor phase current reconstruction method, an error self-correction complementary non-zero vector pulse width modulation method is proposed. Through the analysis of the DC bus sample principle, the minimum sample time is defined, the complementary non-zero vector is used to replace the zero voltage vector, and the current sampling window is extended, thus eliminating the sector boundary unobservable area. At the same time, the generation mechanism of error amplification effect is revealed, and the zero drift is detected and self-corrected by means of double-sampling complementary non-zero vector, which realizes the compensation for current zero drift reconstruction. Experimental results show that the reconstruction error of the proposed method was lower than 1.26%, and the phase current THD was lower than 6.15%.

Aimed at the transient instability of a voltage source converter (VSC) based on phase locked loop (PLL) under weak network conditions and considering the influences of power grid line impedance, VSC reactive power injection and PLL filtering, the transient instability boundary of VSC is comprehensively studied based on the critical voltage in a variety of fault scenarios such as grid voltage sag, frequency fluctuation and three-phase asymmetric fault. Through the analysis of the VSC grid-connected vector diagram in different operation scenarios, the mathematical models of relationships between the grid voltage of VSC grid-connected system and factors (e.g., line impedance and impedance angle, VSC operation power and its power factor, PLL phase-locked error, and grid frequency) in multiple scenarios are established. Then, the transient instability boundary of VSC is indicated based on the critical voltage. Results show that both the line resistance and reactive power injection can directly reduce the critical voltage and improve the stability of the system. The increase or decrease in grid-side frequency will directly lead to the phase lag or lead of PLL and an increase or decrease in line reactance, thus indirectly affecting the critical voltage and further affecting the transient stability of VSC. The PLL pre-filter may cause errors in the phase-locked result, and its phase lag or lead will reduce or increase the critical instability voltage of the system, respectively.

Aimed at the problems of DC bias and frequency variation in a weak grid, a modified inverse Park transform phase-locked loop (IPT-PLL) technology suitable for single-phase grid-connected inverters is proposed. First, the α component after Park transform is used as a reference voltage in the phase detector to solve the problem of DC bias in grid voltage, and an orthogonal component is constructed by the method of 1/4 fundamental periodic delay. Second, the fractional-order delay is approximated by Lagrange interpolation polynomial to reduce the calculation error of delay caused by frequency variation, and the design method for PI regulator is theoretically analyzed. Finally, experimental results show that the modified IPT-PLL proposed has a strong frequency adaptivity, and it can significantly suppress the interference of DC bias in grid voltage. In addition, its dynamic and static performances are satisfying.

With the large-scale integration of wind power and other renewable energy sources, the frequency regulation capacity and effect of traditional frequency regulation power sources are difficult to meet the requirements of power grid. To solve this problem, a comprehensive control strategy based on the frequency regulation signal optimization of a battery energy storage system which assists the thermal power unit to participate in secondary frequency regulation is proposed. First, a simulation model of energy storage that meets the power grid’s frequency regulation requirements is established. Based on this model, the allocation mode of area control error signal and area frequency regulation requirement signal is analyzed in the complex frequency domain, and the switching criterion for frequency regulation signal is determined by combining the advantages of the two control signals. Then, considering the economy and efficiency of energy storage frequency regulation, the allocation coefficient is optimized by a decomposed multi-objective evolutionary algorithm to reduce the frequency offset and optimize the cost of frequency regulation. Finally, the effectiveness of frequency regulation signal switching criterion and multi-objective evolutionary algorithm in optimizing the energy storage allocation coefficient is verified by step disturbance simulation. The comprehensive control strategy is verified by continuous disturbance simulation, and results show that it can not only reduce the system frequency offset effectively, but also lower the operating cost of energy storage.

In the impedance measurement process, since the inverter impedance varied widely, the magnitude of injection disturbance cannot be evaluated in advance. Therefore, it is necessary to adjust the disturbance energy adaptively. The impedance measurement device of disturbance voltage injected in series is taken as the research object, and an adaptive adjustment strategy of disturbance voltage based on disturbance current feedback is proposed. The magnitude of disturbance voltage is adjusted by detecting the responding disturbance current in real time, thus realizing the adaptive adjustment of disturbance energy. Both the disturbance voltage and responding disturbance current are controlled to be within 10% of the steady-state point of the system under test. The effectiveness of the proposed control strategy was verified by hardware-in-the-loop simulations in real time.

As the penetration rate of renewable energy resources in a new power system continues to rise while the proportion of traditional thermal power units continues to decline, the new power system faces severe frequency control problems. Distributed battery energy storage systems (BESSs) provide an effective way to solve these problems. On this basis, a robust load frequency control (LFC) method for distributed BESSs based on sparse communication network is proposed. To suppress the uncertainties related to system operation, a two-tier model predictive control (MPC) is designed to improve the response characteristics of BESSs, thus improving the performance of LFC. To minimize the area control error, the proposed method can satisfy various operating physical constraints of the system. In addition, the influence of communication delay on the performance of frequency modulation participated by BESSs is also considered, and a fuzzy coordination control device is designed to coordinate BESSs and the traditional generator, so that the mis-operation of the traditional generator under the condition of long delay can be avoided. Finally, simulation results show that the response capability and frequency modulation effect of distributed BESSs are better than the traditional methods under parameters such as different values of capacity, rated power, charge and discharge coefficient, state-of-charge and time constant.

With the increasing penetration rate of renewable energy, carbon emissions are reduced. However, the inherent intermittency and volatility of renewable energy also bring problems such as inertia, security and economy to the power system. The battery energy storage(BES) technology has become one of the important means to solve this problem. Under this background, an autonomous control method for BES system oriented to the active support of grid voltage is proposed based on full-state feedback. First, based on sagging K_v(V_g-v_g) and the virtual capacitor C inertia technology, static power support control and dynamic voltage support control modules are designed, so that the BES system can provide power(static) support and voltage(dynamic) support. Second, the voltage controller and current controller are combined by using the full-state feedback method, which makes the design of the proposed controller more systematic and flexible and reduces the voltage oscillations caused by single-phase ground fault. Third, in order to maintain the stability of state-of-charge(SOC) of BES, a BES SOC controller based on regulatory factors is also designed to further improve the autonomous operation ca-pability of the BES system. Finally, a case study of a 14-node DC system was carried out based on MATLAB and a semi-physical simulation platform, and simulation results verified the effectiveness of the proposed method in the cases of double-support of static power and dynamic voltage and single-line ground fault. With this method, the BES system can be connected to any key node in the grid, and the voltage at the point of common coupling in the grid can be actively supported through the local monitoring of disturbance, which is not affected by disturbance and can be operated and controlled independently. In addition, this method can also prevent the converter from overcurrent during transient low-voltage accidents, so that the autonomous operation capability of BES is realized.

Aimed at the problem that the accuracy of photovoltaic array fault diagnosis based on support vector machine (SVM) is not high and it is easily affected by the kernel function and penalty factor parameters, a photovoltaic array fault diagnosis method based on SVM optimized by the seagull optimization algorithm (SOA) is proposed. The SOA is introduced to optimize the parameters of the SVM model, and an SOA-SVM fault diagnosis model based on the optimal parameters is established. MATLAB software is used to build a photovoltaic array simulation model, and the characteristic parameters under different fault types are extracted and further inputted into the SOA-SVM model for fault diagnosis. Experimental results show that the fault diagnosis accuracy of the SVM model optimized by SOA is significantly improved. Compared with the ABC-SVM and PSO-SVM models, the SOA-SVM model converges faster in the optimization process and has a higher fault diagnosis accuracy.

With the scale expansion of a subsea observation network, the stability of its high-power power supply system has attracted attention. First, the impedance models of key parts in the subsea power supply system are established. Considering the characteristics of high power electronic penetration rate, multi-bus cascading and adjacent bus interactive coupling of the subsea DC power supply system, the stability and influencing factors of the system are explored by using the step-by-step analysis method. The analysis result shows that the integral parameter of the controller is the dominant parameter that leads to the instability of the Buck converter, and the proportional parameter of the controller is the dominant parameter that results in the instability of the junction box subsystem. Both an increase in the impedance parameter of the optoelectronic composite cable and a decrease in the inductance parameter are beneficial to improving the system stability. The simulation results based on the PLECS simulation software verify the stability analysis results.

With the large-scale network entry of electric vehicles (EVs), their disorder charging further increases the load peak-valley gap, which has a negative impact on the stable operation of power system. A two-stage optimization scheduling strategy which takes into account the EV load and the energy storage system of batteries is proposed. First, an orderly charging scheduling model for EV is established, which aims at minimizing the absolute peak-valley gap between user charging cost and load. The improved particle swarm optimization algorithm is used to solve this model to avoid peak charging. Second, an optimal scheduling model of peak-shaving and valley-filling for the energy storage system is established with an objective of minimizing the variance of load and the combined cost of energy storage life, which is solved by the improved Harris Hawks optimization algorithm to reduce the peak-valley gap of load. In addition, the optimization results are evaluated and analyzed based on the evaluation index of peak-shaving and valley-filling. Finally, a simulation experiment is carried out with the measured load power of one power network as an example. Results show that under the proposed two-stage optimization scheduling strategy, the peak load decreases by about 147 kW, the valley load increases by about 223 kW, and the peak-valley gap deceases by 46.73%, indicating that this strategy can effectively improve the load curve, alleviate the pressure on power supply during the peak load period and ensure the safe and stable operation of power grid.

To avoid the dynamic problems caused by dynamic and static loads in the operation of a power electronic power system, which affect the system stability, a modeling and analysis method for the voltage power angle dynamic stability is proposed. The continuation method is used to track the equilibrium solution manifold of the power system, and the small disturbance analysis method is used to calculate the voltage power angle state matrix to judge the dynamic stability of voltage power angle. By means of the power system stability mode discrimination method, the correlation between voltage and power angle state variables in the instability state is analyzed, the system instability category is determined, and the construction and analysis of voltage and power angle dynamic stability model is realized. Experimental results show that the load model is directly related to the category of dynamic instability of power system in an electronic environment. The static load model is easy to cause power angle instability, while the dynamic load model is easy to cause voltage instability. The time-domain simulation results are consistent with the discrimination results of state variable participation factor. Through the tests of power angle instability and voltage instability, the generator angle and node voltage are analyzed. It is proved that the proposed method has a good effect in the analysis of voltage and power angle dynamic stability, providing certain reference value for researches in the field of power system engineering.

The power supply load of a high voltage direct current (HVDC) power supply system is prone to be affected by signal interruption, which will result in the unstable operation of power supply system. To effectively improve the management efficiency of power supply system, an optimization method for the management efficiency of HVDC power supply system based on genetic algorithm is proposed. The optimization of management efficiency is transformed into the problem of load distribution, and a load distribution control strategy of efficiency optimization is adopted to reasonably distribute the load current in the HVDC power supply system. The genetic algorithm is used to optimize the management efficiency of the HVDC power supply system, so as to optimize its management efficiency. Experimental results show that the system management efficiency can be adjusted through the independent operation of dual power supplies, thereby improving the efficiency of power supply system. In addition, the running time of this method was maintained at 90-120 s, the optimization time was short, and the efficiency was high.

With the continuous advancement of medical technology, implantable medical devices (IMD) are increasingly applied in clinical practice. Since the traditional battery-powered method will bring additional tissue damage and surgical costs to patients, the use of wireless power transfer (WPT) technology to power IMD will become a trend in the future. However, how to design a high-efficiency IMD-WPT system in a limited space is very challenging. To this end, the performance characteristics of five WPT technologies suitable for IMD are compared. Then, the magnetic resonance WPT technology is taken as an example to introduce the key issues in the design of a magnetic resonance IMD-WPT system. Finally, the application status of part of the magnetic resonance WPT technologies in some typical IMD is combined, and the research direction of IMD-WPT technology in the future is discussed.

To solve the problems of constant-voltage output instability and low efficiency caused by load resistance and coupling coefficient fluctuations in the dynamic charging process of an electric vehicle, a novel dual-side control scheme is proposed. In this scheme, the constant-voltage control output is realized by adjusting the pulse width angle θ of a high-frequency inverter at the transmitter, and the maximum efficiency tracking (MET) control of the system is realized by adjusting the pulse width angle φ of a controllable rectifier at the receiver. Through theoretical analysis, it is proved that when the derivative ∂[sin(θ/2)]/∂[sin(φ/2)] is a specific constant, the system can always work under the operating condition of maximum efficiency. Compared with the same type of MET control scheme, the proposed scheme does not need to install expensive current or power sensors on the transmitter, which reduces the system’s development cost to a certain extent. To verify the rationality of the proposed scheme, an experimental verification device with a rated power of 360 W was built, and experimental results fully proved the rationality and effectiveness of this scheme.

Compared with the traditional silicon(Si) devices, the gallium nitride(GaN) devices have lower parasitic parameters, a faster switching speed and a smaller on-resistance, which will easily lead to the phenomenon of continuous oscillation during their switching-on process and further result in the circuit instability. Therefore, it is necessary to suppress this phenomenon in practical circuits. Under this background, a negative conductance model of a bridge circuit under the conventional driving scheme is established at first, and the oscillation stability of the circuit is analyzed. Then, by adding optimization to the conventional driving scheme, the corresponding negative conductance model is established. The optimization schemes of series damping represented by changing the resistance and adding ferrite beads and those of parallel low impedance represented by adding RC snubber are selected, respectively. With this model, the influence of adding the driving optimization schemes on the oscillation stability of the circuit can be identified, and the changes in the stability before and after the addition were verified by experimental results, providing a reference for the driving circuit to select its appropriate driving optimization scheme.

With the development of wide band gap devices, SiC MOSFET has been widely applied, and the research on its short-circuit protection has become an important topic to ensure the reliability of power electronic equipment. In view of the short short-circuit withstand time of SiC MOSFET and the difficulty in short-circuit fault protection, a short-circuit detection method for SiC MOSFET based on a planar differential Rogowski coil is proposed, which realizes a rapid identification of short-circuit fault by measuring the drain source current of the circuit and has advantages such as a fast response speed, a strong anti-interference capability and complete isolation from the main circuit. First, the working process of the SiC MOSFET short-circuit detection method based on the planar Rogowski coil is introduced. The partial element equivalent circuit (PEEC) modeling method for planar Rogowski coil is studied in detail, and an equivalent model which can reflect the coil’s high-frequency characteristics is obtained. At the same time, the influence of the geometric structure of the planar Rogowski coil on its performance is analyzed, and an optimal design scheme considering both the high gain and high bandwidth is proposed. Aimed at the problem of low measurement accuracy of the Rogowski coil in an environment with strong electromagnetic interference, a scheme of using the differential coil is put forward to improve the anti-interference performance. Finally, the anti-interference per-formance of the designed planar differential Rogowski coil and the reliability of short-circuit protection method based on this coil were verified by experimental results.

To solve the difficulty in online life prediction of silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET) under practical working conditions, a digital implementation method for SiC MOSFET module life prediction based on particle swarm optimization-back propagation (PSO-BP) neural network was proposed. First, the saturation voltage drop of SiC MOSFET was extracted by a saturation voltage drop platform as the temperature-sensitive electric parameter, and a junction temperature prediction scheme based on experimental data was established. Second, a life prediction scheme based on PSO-BP neural network was established by using a power cycling accelerated aging experimental platform to extract the aging characteristic data. Third, the junction temperature prediction scheme and life prediction scheme were transplanted to field programmable gate array to realize the digitization of SiC MOSFET life prediction. Finally, a circuit was designed to verify the proposed method. Experimental results show that the error between the digital junction temperature and real junction temperature was 4.73 ℃, and the percentage of error between the predicted life times and real life times was 4.1%, which proves that the proposed life prediction method is realized digitally and can accurately predict the life times of SiC MOSFET module.

In the traditional power module automatic layout optimization algorithm, the electrical evaluation is inefficient and takes up a lot of computing time. To solve this problem, lattice Boltzmann method (LBM) is used to replace the traditional evaluation method. Since LBM does not need to solve multiple invertible matrices, it can quickly judge the rationality of electrical interconnection and calculate the voltage/current. With the program of automatic layout design based on the genetic algorithm, an evaluation method of two-dimensional layout is established by using a D2Q4 lattice type, and the accuracy of the evaluation result under the layout scheme is verified by ANSYS Q3D software simulation. A comparative test was conducted in Python 3.10, and results show that LBM reduces the total time of scheme evaluation by 75.4% on average. Moreover, the more the number of loops in the evaluation scheme, the greater the computing advantage of LBM.

Harmonic and electromagnetic interference (EMI) filters are two important output filters used to sup-press the harmonic distortion and EMI noise in grid-connected inverters. Harmonic and EMI filters are combined by planar magnetic integration to reduce the volume and weight. Through the selection of an appropriate magnetic core, the common mode and differential mode inductors are integrated into the same core by drawing PCB planar coil. To integrate the discrete capacitors and further realize the planar magnetic integration of EMI filter, the dielectric is inserted into the PCB and the layer connection mode is reasonably planned. A symmetric LCL filter is used to replace the traditional asymmetric structure of magnetic integration. Furthermore, by designing the air gap in the center pillar of the magnetic core and reasonably arranging the planar windings, the inductors of LCL harmonic filter are also integrated into the same magnetic core unit to form an LCL-EMI planar magnetic integrated filter. A gallium nitride single-phase inverter platform was built, and the LCL-EMI filter with planar magnetic integration was experimentally analyzed to verify the feasibility of the planar magnetic integration method.

The traditional fault diagnosis methods for power transformers cannot detect the power faults accurately or ensure their normal operation. Therefore, a fault diagnosis method for power transformers based on wavelet packet transform and support vector machine (SVM) is proposed. For the power signal collected from a power transformer, the improved minimum noise fraction (MNF) transform denoising is used to denoise, and the noise matrix is estimated by the weighted neighborhood mean method. After the estimation, the improved MNF transform is used to effectively realize image dimensionality reduction and denoising, extract the signal characteristics, and divide the signal into low- and high-frequency part by means of wavelet packet transform to obtain the wavelet packet energy feature vector. The obtained wavelet packet energy feature vector is input into an SVM classifier, and the output results from the SVM classifier are used to realize the state recognition and fault diagnosis of power transformer. Experimental results show that the proposed method can effectively diagnose the faults in the power transformer, such as iron core short-circuit, coil interlayer short-circuit, bushing-to-ground breakdown, coil insulation resistance drop and bushing-to-bushing discharge, and the fault diagnosis accuracy was higher than 98.5%.