In order to improve the efficiency of identification and diagnosis of distribution network line faults and improve the reliability of power supply, this paper adopts a method based on wavelet entropy to construct a distribution network line operating condition characteristic gene bank. Firstly, the distribution network line simulation model is built to extract the operation data, and then, combined with the effective simulation data, the feature extraction algorithm model based on wavelet entropy is built, and finally, the characteristic gene bank is developed based on the feature data. The simulation results show that the feature extraction algorithm and characteristic gene bank based on wavelet entropy can effectively identify and diagnose a variety of operating conditions of distribution network lines, which meets the requirements of sustainable development of distribution network.

Large-scale electric vehicles are connected to the park integrated energy system (PIES), in order to improve the energy utilization rate, reduce the pressure on the park’s power grid, and realize low-carbon operation, this paper proposes a two-tier low-carbon optimized operation strategy that combines electric vehicles and efficient hydrogen use. Firstly, the disordered charging of the electric vehicles is simulated based on the spatio-temporal feature correlation, on the basis of which real-time tariffs are utilized to guide the electric vehicles for orderly charging. Combining the improved power-to-gas (P2G) two-phase technology, the park participates in the carbon trading market. The laddering carbon trading mechanism is introduced to minimize the system’s cost of purchasing energy, the cost of carbon trading, and the cost of abandoning the wind as a target function. The improved whale optimization algorithm (IWOA) is adopted for solving the problem. Finally, the scenarios are compared to verify the economy and environmental benefits of the two-tier optimal scheduling strategy proposed in this paper.

Recursive Fourier algorithm is a commonly used digital signal processing algorithm for protection relays. Its characteristic is to use the last calculation result to calculate the current result. Its calculation efficiency is very high. However, the recursive algorithm has a memory effect. Errors caused by accidental factors will be kept and be difficult to detect, bringing hidden dangers to the operation of the protection device. In this paper, a fault-tolerant mechanism suitable for recursive algorithm is proposed to eliminate the memory effect and prevent irrecoverable calculation deviation caused by occasional or accumulated errors, thus effectively preventing such problems from causing misoperation or failure of protection devices.

In response to the intermittency and uncertainty of renewable energy generation, which leads to changes in the model parameters of the electric spring (ES) system and a decrease in control performance, this paper proposes a model-free adaptive control (MFAC) strategy applied to the ES system. This strategy involves updating the control law equation and pseudo-derivative estimation equation in real-time using only the input-output data of ES. Through the compact form dynamic linearization algorithm, the input-output data of ES is described as a compact form dynamic linearization data model to replace the non-linear system of ES, thus achieving model-free adaptive control of ES. To verify the superiority of the control strategy proposed in this paper, the voltage stabilisation effect of the ES system is simulated by Matlab/Simulink. The results show that the voltage stabilisation response speed is improved by 0.07s, and the voltage waveform distortion rate is reduced by 6.43%, compared with the traditional proportional integral (PI) control strategy.

With the proposal of China’s “dual carbon” goal and the construction of a novel power system, how to reduce the total carbon emissions of power generation enterprises and increase the share of renewable energy generation is an important issue facing China at present. In this paper, the conventional electric energy market trading paradigm is improved, and an optimization model for electricity trading considering carbon markets and renewable energy quota system is proposed. The optimization model is constructed with the goal of minimum carbon emissions of power generation enterprises and minimum customer purchase cost of electricity, and the model is solved by using the Cplex solver. The optimized trading paradigm is compared with the conventional electric energy market trading paradigm, and the case analysis verifies that the optimization model corresponding to the trading paradigm in this article can well decline the carbon emission and customer purchase cost of electricity.

In the context of “dual carbon” goal, integrated photovoltaic storage and charging station (IPSCS) can effectively solve the problem of independent operation of multiple types of flexible resources. To enhance the collaborative consumption capacity of source load and reduce carbon emissions, this paper proposes a multi-timescale day-ahead operation strategy for IPSCS that considers carbon emission stratification and source load interaction. Firstly, hybrid prediction model and Monte Carlo method are applied to historical data to derive typical photovoltaic output and electric vehicle load scenarios, respectively. Secondly, the objective function of the mathematical model of the operation strategy of the integrated station is minimum comprehensive planning cost, minimum carbon emission, and maximum utilization of new energy. The model is solved using an improved whale optimization algorithm (IWOA) incorporating an opposition-based learning strategy and diversity variation processing. Finally, the rationality and effectiveness of the proposed strategy are verified through case analysis.

Compared to other primary equipments such as busbars, lines, and circuit breakers, transformers have a more complex structure and are the only equipment in the power system that connect different voltage levels. In addition, the influence of the Y/D transform makes the fault characteristics complex and variable, making it difficult to locate the fault point. The fault localization depends on the experience of the engineer. There is an urgent need for a complete automated fault location system. This article first classifies the possible situations that may cause transformer protection starting or tripping, and then sets fault localization criterion step by step. The criterion greatly enhances the automation level of transformer fault localization and has good engineering implementation value. The feasibility and accuracy of this method are proved through multiple sets of simulation waveforms.

This article analyzes the characteristics of single phase grounding faults and cross line grounding faults in the same tower double circuit line, as well as the impact of zero sequence mutual inductance on grounding distance protection, in response to the misoperation fault of under range longitudinal distance protection during a cross line grounding fault on the same tower double circuit line. It is concluded that the additional impedance caused by zero sequence mutual inductance is the fundamental reason for the reduction of grounding distance protection range and the refusal of protection. In order to solve the problem, an adaptive zero sequence mutual inductance compensation method is proposed. The new method based on the adjacent zero sequence current injection and local auxiliary judgement can enable the compensation adaptively. The performance of the proposed method is evaluated based on the real time digital simulation system, and results show that this method is valid.

This paper compares the advantages and disadvantages of closed water cooling systems and open water cooling systems in terms of heat transfer efficiency, footprint, water consumption, and cost. The heat transfer capacity, site environmental conditions, inlet temperature of the phase modulator heat exchanger, and other requirements are taken into account for installing a phase modulator at a certain converter station, as well as the economic investment and operational factors. It is ultimately determined that the external water cooling system for the phase modulator at the converter station adopts an open water cooling scheme. The design scheme of external cooling system for the phase modulator is given in this paper, hoping to provide reference for the selection and design of the external cooling system for phase modulator in subsequent projects.

In order to solve the problem of high redundancy and low positioning accuracy of traditional cable fault location spectrum data, this paper proposes a high precision cable fault location method based on chirp-Z transform (CZT). Firstly, according to the transmission line theory, the distribution parameters and reflection coefficient characteristics of the fault cable are analyzed. Then, CZT is performed on the real part of the reflection coefficient. Finally, iterative filtering is used to denoise and obtain the cable fault location spectrum. The results show that the fault point recognition error of the proposed method is 0.025%~0.275%. Compared with fast Fourier transform (FFT), the proposed method has the advantages of refined location spectrum, high resolution, low redundancy and high fault location accuracy.