In order to ensure the security and reliable operation of stability control systems, “high-fidelity” whole-set field tests (HWFTs) on critical stability control systems is applied to China Southern Power Grid (CSG) every year. The procedure design criterion and admittance testing procedure of various types of HWFT for CSG are introduced in this paper, the case design of HWFTs for stability systems by chosen criterion is given. The test results of HWFTs in 2020 verify the functionality of the control strategy program, the stability control equipment, the communication channels, the actuator breakers, and the background supervision system, and the whole-set elapsed time of the response of the grid is analyzed. Results show that the actual elapsed time in all these tests meets the operating and control requirements of CSG.

The reliability of the ultra-high voltage direct current (UHVDC) lines with large capacity is important to the power system security. The existing studies about the UHVDC reliability is for long-term purpose, and can not show the short-term change of the reliability after component failures. In this paper, based on the detailed structure of the converter station of UHVDC, instantaneous state probability and steady-state aggregation algorithm, a transient hierarchical equivalence algorithm is proposed to derive the transient state space model of the converter station. The time-dependent reliability indices for the bipolar availability and bipolar outage rate are proposed. Based on the average probability algorithm, the average state probability and reliability of the converter station with a period of time are found. The proposed models extend the reliability model and indices of the UHVDC system, which is beneficial to evaluate its short-term risk. Compared with the transient state probability algorithm, the validity of the proposed transient hierarchical equivalent algorithm is verified. The results show that the transient state probability of UHVDC converter station is different from its steady-state value, and converges from different initial states to the steady-state value.

In the real-time simulation, the converter transformer containing a large number of switching devices has the problem of insufficient storage capacity and computing power of the simulation hardware, which causes the simulation to be overloaded and seriously affects the development of the HVDC simulation work. In response to this problem, the ideal transformer model interface algorithm is used to design a converter transformer that implements on-load voltage regulation. Taking the CIGRE standard HVDC system test model as an example, offline and real-time simulations are performed on Simulink and RT-LAB platforms respectively. The steady-state and transient results of the ITM-type converter transformer without tap switch and the converter transformer with tap switch are consistent. Finally, it is concluded that the method of realizing the converter transformer based on the ideal transformer model interface algorithm can be applied to the construction of the real-time simulation test platform of DC transmission.

Aiming at the optimal dispatch problem of distribution system with demand response (DR), this paper analyzes the challenges in DR modeling from the perspective of the cyber-physical-social system, i.e., finite data information at cyber level, bounded rationality at social level and source-load interaction characteristic in the physical level. Thus a hybrid model and data driven DR modeling method is developed, which taking the limited data information and the bounded rationality into consideration. Furthermore, a Stackelberg game-based optimal dispatch model is proposed to represent the interaction behavior between distribution network operators (DNO) and electricity consumers, and the proof of the existence and uniqueness of Stackelberg equilibrium is given. Finally, the actual data and electricity price of one province power grid in China are adopted for simulation study. The simulation results show that the proposed DR modeling method can well reflect the user’s actual response behavior and the Stackelberg game-based optimal dispatch approach is helpful to the implementation of real-time price mechanism compared with the time of use mechanism, which plays an important role in reducing DNO and user costs and promoting the utilization of renewable energy.

Based on the detailed analysis of the evolution of key characteristics of power distribution network with the “carbon peaking and carbon” target background, this paper sorts out the challenges existing in intelligent sensing and fault detection of power distribution network. Then the challenges of distribution network intelligent sensing and fault detection are combed, and the existing problems and the methods of realizing intelligent perception with the help of artificial intelligence technology are summarized. Next, the difficulties of distribution network fault diagnosis and fault location are analyzed, and the application and research progress of artificial intelligence in distribution network fault diagnosis and fault location are introduced. For further analysis and fault diagnosis of complement each other, in this paper, takinga 10 kV overhead line as an example, the role of artificial intelligence in intelligent perception of distribution network and the performance comparison of different artificial intelligence algorithms for partial discharge fault detection are analyzed in detail. Finally, the applications of artificial intelligence in intelligent sensing and fault detection of distribution network are reviewed.

High precision wind power prediction plays an important role in the safe and stable operation of power system and the optimal allocation of energy system. In this paper, in order to extract the hidden information from the multi-dimensional wind power historical data, accurately select the features highly related to the prediction target, and overcome the short-term memory problem of time series, an ultra-short-term wind power forecasting model is proposed which is based on convolutional neural network and bidirectional long short term memory network (CNN-BiLSTM), combined with dual-stage attention mechanism and Bayesian optimization algorithm. Firstly, in order to autonomously mine the data association between input features and wind power data, and further highlight the impact of important high-dimensional features, the attention mechanism is added to the common CNN to build a feature attention module. Secondly, the attention mechanism is introduced into the output of the BiLSTM network to form a temporal attention module, which enhances the long-term memory ability and strengthens the influence of important historical information. Finally, the Bayesian optimization algorithm is used to optimize the hyperparameters of the proposed model, and the optimal hyperparameters can be selected to show the best performance of the model. The verification experiment is conducted with actual data from a wind farm in Northwest China, accuracy of single-step prediction model is 95.58%, and accuracy of 4 hours ahead ultra-short-term multi-step prediction model combined with NWP information is 90.44%. The experimental results show that the proposed model is more accurate than others.

The satellite second clock signal is usually used for synchronization in the two-terminal traveling wave positioning device. To eliminate the influence of ionosphere and tropospheric delay, receiver clock error and satellite clock error, a method of generating high precision synchronous clock based on frequency difference regression-difference observation common-view timing model is proposed. Firstly, the frequency difference quadratic regression equation model of crystal oscillator second clock and satellite second clock is established, and the current estimation of regression coefficient of regression equation model is calculated in real time, and the correction value of crystal oscillator second clock is calculated by estimation. The satellite timing differential network is established by using the differential observation common-view timing model to reduce the random drift error of the user’s satellite second clock signal in the transmission process. The modified satellite second clock signal is used as a parameter to improve the fitting accuracy of the frequency difference regression model between the crystal oscillator second clock and the satellite second clock.

The rapid development of electricity demand and the electric vehicle industry will accelerate the construction of urban substations and charging/swapping stations, but it is also limited by existing land resources and other issues. Therefore, based on the prefabricated substation with the advantage of intensive resource utilization, this paper proposes an optimal operation strategy under the multi-station integrated service mode, considering the integration of the prefabricated substation and the electric vehicle charging/swapping station. Firstly, the comprehensive service framework of prefabricated substation-charging/swapping station is established, and the feasibility of its integrated operation is analyzed. Within this framework, the virtual energy storage capacity of electric private vehicles and the swapping demand of electric taxis are analyzed, and a battery timing simulation model considering discharge behavior (vehicle-to-grid, V2G) of the swapping station is proposed. Finally, the charging and discharging behaviors of batteries were reasonably regulated according to the characteristics of EV travel, charging and discharging, and battery energy storage in the charging/swapping stations. The result shows that the proposed method can play a role of smoothing load fluctuation and cutting peak load and filling valley by reasonably evaluating the requirements of virtual energy storage and swapping demand.

The structure of the protective gap is simple, but the air gap can not quickly extinguish the arc, so the trip rate of the line is high. In order to solve this problem, this paper puts forward a method of installing an air cannon beside the protection gap, which can take away the heat of the arc and make the arc be drawn thin by ejecting high-speed air, so as to speed up the extinction of the arc. And the air gun can automatically inflate after arc-extinguishing for the next action. Based on magnetohydrodynamics (MHD) theory, the new protection gap model and arc simulation model are established by COMSOL software. According to the simulation calculation, the arc can be pulled down to 25% of the original thickness by the protection gap of self-charging air gun, which is easier to extinguish. Because the air flow takes away the heat, the temperature at the arc center is only 1/3 of the traditional protection gap, and the arc is easier to be extinguished. Field experiments show that the arc in the protection gap with self-charging air cannon can be extinguished in 13.3 ms, which is much less than the arc extinguishing time of the traditional protection gap, and the arc extinguishing time is only 31.8% of the traditional protection gap at most.

The presence of air bubbles in oil-paper insulation structure can cause distortion of the surrounding electric field and cause partial discharge. In order to clarify the motion characteristics of bubbles in transformer oil, based on finite element simulation methods, the motion trajectory and vertical direction velocity change of bubbles under different electric field intensities are studied. The results show that the extremely inhomogeneous electric field has a push-off and tensile effect on the bubbles, and the distance of the bubbles shift in the horizontal direction increases with the increase of the electric field strength, the movement speed of the bubbles rises first rapidly and then slowly oscillates and decays, and the oscillation frequency decreases at the end of the floating stage, and the speed of the bubbles decreases with the increase of the electric field strength when they are near the needle electrode, but the speed of the entire floating motion increases. A platform for observing the motion of bubbles in the oil-paper insulation structure under the extremely inhomogeneous electric field is built, and the trajectories of the bubbles in different electric fields are recorded, the observations are basically consistent with the simulation. However, with the continuous improvement of the electric field strength, clusters of bubbles are easy to form under the needle electrode, which seriously affects the insulation. The results of the study can effectively assess the operating state of power equipment, which is of great significance for further construction of the digital twin of oil-immersed power equipment.

In the weak current network environment, due to the grid equivalent impedance, the coupling degree between inverters is enhanced when multiple inverters operate in parallel, resulting in resonance, and the whole system is difficult to be operated in a steady state. An overall resonance suppression strategy is proposed based on the notch filter introducing virtual equivalent admittance to the common coupling point. Firstly, the closed-loop output equivalent impedance model of a single inverter is established. Based on this model, the resonance characteristics of multi machine parallel system are analyzed by Thevenin equivalent. Secondly, the closed-loop Norton equivalent model of parallel operation of multiple inverters is constructed, and the Nyquist criterion for judging the stability of parallel operation of multiple inverters is derived. Then, the obtained Nyquist criterion is used to judge the correctness of the proposed overall resonance suppression strategy. Finally, the effectiveness of the proposed resonance suppression strategy for parallel operation of multi grid connected inverters is verified by simulation and experiments.

In the engineering design of ultra-high voltage isolated transmission lines, due to the influence of concentrated load of the tension string and the interphase spacers, it is difficult to calculate the length of the interphase spacers accurately, which leads to difficulties in construction and installation, corona loss, and abrasion of wires. For this reason, a method is proposed for calculating the length of interphase spacers on ultra-high voltage isolated tower considering the influence of concentrated loads. By fully considering the influence of the weight, quantity, installation position and other factors of the concentrated load on the calculation of the length of interphase spacers, the calculation accuracy is improved. Firstly, the conductor sag formulae are introduced considering the influence of the concentrated load of the tension string and the interphase spacer. Secondly, a length calculation method is proposed for the interphase spacer when the tension tower head have the same size, or have different sizes, or have certain rotation angles. Finally, the accuracy of the method in this paper is verified via engineering examples and measured values. The results show that by considering the influence of the concentrated load of interphase spacer bar, the method proposed in this paper has a smaller calculation error and is more accurate than the traditional method. The research results can provide references for the theoretical research and engineering design of the length of the interphase spacer in isolated gears.

The clearing price in the electricity spot market is an important reference for market players to make bidding decision and evaluate revenue. The clearing price is affected by many factors and fluctuates frequently, which brings difficulties to the selection and evaluation of forecasting model. Firstly, the requirements of evaluation indexes for price prediction errors are summarized and the deficiencies of traditional indexes are analyzed. Then, in view of the different economic consequences caused by price prediction errors of different market players, a risk-based error assessment index is proposed. For operators and power generators, the error values during different time periods are given as weights. For retail companies, this paper analyzes and predicts whether the positive and negative price difference between day-ahead and real-time will affect their bidding strategy. For end users, the conncetion between forecast error and cost of electricity is analyzed. The index can accurately reflect the risk cost caused by the prediction error, and can be used to choose the appropriate prediction model according to the demand. Finally, the use of Guangdong spot market full-month trial operation data shows that the proposed method enables different players to accurately select the price prediction model that makes their decision-making risk the lowest. After the method is applied to industrial users’ decision-making, the cost of electricity purchase can be reduced by 1.76%~2.97%.

With the deepening of the marketization of power system, the scale of transmission congestion of power system which is based on the nodal price mechanism will increase continuously, and it is necessary to provide an effective congestion management method for power network users. In this paper, under the study of the congestion management method abroad and the trading structure as well as market congestion revenue distribution method of southern China (starting from Guangdong provcince) electricity market, the existing problems of the current congestion revenue allocation method are pointed out, and a design of congestion revenue right allocation mechanism that adapts to the Guangdong electricity spot market is put forward. Additionally, an example is used to simulate the full process of the congestion revenue right allocation including nomination, allocation and settlement in order to verify the effectiveness of the mechanism, which ensures that the congestion revenue is returned to load in a fair, just and reasonable manner.

In order to solve the problem of scarcity of labeled collusion data in the spot market, a collusion recognition model based on semi-supervised support vector machine is designed. Firstly, a set of collusion identification index system is designed and its detailed calculation method is introduced. Secondly, the Topsis model modified by Delphi method is used to make a preliminary judgment of the unit, and the collusion recognition training set is constructed. The possibilities of collusion of the unit are divided into “high”, “medium” and “low”. Then, a collusion recognition model based on semi-supervised support vector machine is proposed. The collusion recognition model is trained by using labeled collusion recognition samples, and the unlabeled samples are labeled. The group of labels with the largest classification interval is selected as the final label. The original label samples and the new labeled samples are mixed to retrain the collusion recognition model. Finally, the effectiveness of semi-supervised support vector machine algorithm is verified by an example of spot market data in a certain region.

This paper reviews the history and current situation of the research on the glaze icing process and typical galloping characteristics of transmission lines. Firstly, the effects of wind speed, ambient temperature, supercooled water content in air, droplet diameter, wire transmission current and water film thickness on the glaze icing process are emphatically analyzed. Secondly, two research methods of experimental observation and numerical simulation are introduced, and the mechanism of glaze icing on the transmission line is discussed from three aspects of thermodynamics, fluid mechanics and electric field. Thirdly, the typical crescent-shaped and fan-shaped icing sections of transmission lines are discussed. The aerodynamic characteristics of glaze icing on the transmission line are analyzed from four aspects : wind attack angle change, icing thickness, turbulence intensity and average airflow velocity. The glaze icing process of transmission lines is divided into three stages, namely, only water film on the surface of transmission lines, thin icing on the surface of transmission line and thick ice layer on the surface of transmission lines. The mechanism of cable-like wind-rain excitation, vortex-induced vibration, classical theory of icing galloping of transmission line and other theories of icing galloping of transmission line are expounded in turn. Then, the differences between glaze-icing process of transmission lines and airfoils of are analyzed from three aspects of wind speed, water film flow and conductor motion. Finally, on the basis of summarizing the previous research results of glaze icing on transmission lines, the model of glaze icing on transmission lines and its possible research direction in the future are pointed out.