Search

In the transactional processes within a multi-building microgrid system, it is imperative to safeguard stakeholders’ interests and ensure stable, economically efficient operation. Therefore, this paper proposes an integrated interactive control of distribution systems with multi-building microgrids based on game theory. Initially, an interactive framework encompassing superior power grids, distribution network operators, and multi-building microgrids is proposed. This framework establishes a master–slave game model between distribution network operators and multi-building microgrids. Additionally, it introduces the concept of Soft Open Points between building microgrids to enhance system operational safety while also reducing economic costs for distribution network operators. Subsequently, to maintain solution accuracy and optimality, it employs linearization and cone relaxation methods to transform the original model into a mixed-integer second-order cone programming model. Furthermore, it enhances an iterative search method and the price mechanism based on supply and demand ratios. The revised price mechanism serves to boost the participation of building microgrid users in energy regulation, while the iterative search method effectively resolves the equilibrium point of interest among all game participants. Finally, a simulation analysis is conducted on an IEEE-33 test system, and the effectiveness of the proposed strategy is verified by comparing three schemes.

Demand–response (DR) can provide the economic flexibility required to adapt a high proportion of renewable energy in the context of a smart grid. This paper proposes a transactive DR framework to enable the multi-time-scale proactive participation of demand-side flexible multi-energy resources. In this framework, the distribution system operator distributes the real-time DR request and the high renewable penetrated multi-energy prosumer aggregators provide the ancillary services based on their adjustable potential. To facilitate such multi-time-scale prosumer–operator interactions, a flexibility potential evaluation method is developed for the quantification and pricing of prosumer flexibility. The positive and negative flexibility potential of the demand-side prosumer aggregators are defined as deviations from the optimal pre-dispatch operation, which are further quantified using the aspects of flexible time and power. Based on the introduction of a flexibility pricing mechanism to identify the economically optimal ancillary service requirements, each prosumer aggregator performs an optimal real-time DR scheduling. Case studies over several DR schemes are performed to confirm the effectiveness and superiority of the proposed method on the economy and flexibility of the system.

Different types of partial discharge (PD) cause different damages to gas-insulated substation (GIS), so it is very important to correctly identify the type of PD for evaluating the GIS insulation condition. The traditional PD pattern recognition algorithm has the limitations of low recognition accuracy and slow recognition speed in engineering applications. To effectively diagnose the GIS PD type and safeguard the safe and reliable operation of the distribution network, a GIS PD method based on improved CBAM-ResNet was proposed in this paper. And the improved CBAM-ResNet takes advantage of the residual neural network and attention mechanism. In particular, the channel attention module and the spatial attention module are connected in parallel in the improved CBAM. The experimental results showed that the GIS PD pattern recognition method proposed herein has a recognition rate of 93.58%, 95.00%, 93.55%, and 93.88% against the four PD types. Compared with the traditional PD pattern recognition algorithm, the algorithm has the advantages of a lightweight model and more accurate recognition results, which carry better engineering application values.

Oil-pressboard insulation in transformers is prone to surface tracking or creeping discharge during operation. The oil-pressboard interface is believed to be one of the weakest points in the insulation system. In this paper, AC flashover characteristic at the triple junction of the oil-pressboard interface under a slightly inhomogeneous electric field has been studied. The results showed that the creeping discharge always started at the triple junction, then developed along the pressboard (PB) surface, and finally reached the opposite electrode. The reason was that the triple junction was subjected to the maximum electric field strength. The field strength corresponding to the breakdown of the pure oil gap (POG) was decreased with the increment in the gap distance between electrodes due to the volume effect. As a comparison, the field strength corresponding to the breakdown for PB only changed slightly with the gap distance. Besides, the breakdown electric field of both POG and PB hardly changed when the electrode diameter increased. The above results could be applied to the inverse calculation and estimation of the flashover voltage levels under longer gap distances with any electrode diameter. Moreover, the relative position of the oil gap and PB could influence the flashover voltage levels. The breakdown voltage with PB directly contacting the ground electrode was 10% higher than that with PB directly contacting the high voltage electrode. This could be explained by the different charge behavior. The obtained results could provide a reference for the insulation margin design in ultra-high-voltage transformers.

In electrical engineering, partial discharge (PD) measurement has been widely used for inspecting and judging insulation conditions of high voltage (HV) apparatus. However, on-site PD measurement easily becomes contaminated by noises. Particularly, sinusoidal noise makes it difficult to recognize real PD signal, thus leading to the misjudgment of insulation conditions. Therefore, sinusoidal noise removal is necessary. In this paper, instantaneous frequency (IF) is introduced, and the synchrosqueezing transform (SST) as well as singular spectrum analysis (SSA) is proposed for sinusoidal noise removal. A continuous analytic wavelet transform is firstly applied to the noisy PD signal and then the time frequency representation (TFR) is reassigned by SST. Narrow-band sinusoidal noise has fixed IF, while PD signal has much larger frequency range and time-varying IF. Due to the difference, the reassigned TFR enables the sinusoidal noise to be distinguished from PD signal. After synthesizing the signal with the recognized IF, SSA is further applied to signal refinement. At last, a numerical simulation is carried out to verify the effectiveness of the proposed method, and its robustness to white noise is also validated. After the implementation of the proposed method, wavelet thresholding can be further applied for white noise reduction.

The characteristics of the streamer discharge development between the dielectric-coated sphere-plane electrodes in water are described. The analysis of the discharge images and current waveforms has shown that the streamer propagation is composed of the generation of the microbubbles and the discharge in the bubbles.

A dielectric-coated sphere-plane electrode system was designed and used for the generation of streamer discharges in water. To study the streamer initiation and propagation mechanisms, the effect of conductivity was investigated under pulse voltage. Increasing water conductivity caused the decrease of streamer initiation voltage and streamer formation time delay. Under the same applied voltage, the maximum streamer length was inversely proportional to water conductivity, whereas the streamer brightness was proportional to the water conductivity. The mean streamer velocities were dramatically different with different water conductivity and the influences of interactions between streamer branches on the streamer propagation were inevitable under high applied voltage. Based on the analyses of these experimental results, it can be concluded that streamer initiation in water is triggered by the micro-gap breakdown in the coating while streamer propagation may be a gaseous or electronic process, which is dependent on applied voltage and water conductivity. [ABSTRACT FROM AUTHOR]

The production of large volume streamer discharges is essential to the industrial application of such discharge in water. The use of dielectric-coated electrode was found to have a great influence on the initiation of the streamer discharge as well as the formation of streamer channels. In this paper, a sphere-ring electrode configuration, in which the sphere was coated with a kind of silicon rubber, was put forward to generate multiple radial streamer discharges in tap water by applying a pulse voltage. Different from the previous methods which need very high electric strength and short pulse duration, this kind of electrode configuration can generate large volume streamer discharges in water easily at lower voltage amplitude. The effect of the pulse parameters, such as pulse amplitude and pulsewidth, on the streamer-channel length has been investigated. The influence mechanism of the coated dielectric on the streamer initiation and propagation is discussed in this paper. [ABSTRACT FROM AUTHOR]