Valve side bushing is an important part of UHV converter transformer. In this paper, the typical structure and layout of converter transformer valve side bushing in the high voltage valve hall are analyzed, the actual operating voltage waveform is discussed, and the electric field simulation model of high voltage valve hall Y connection converter transformer (HY converter transformer) valve side bushing is established with the FEM software ANSYS, then the electric field distribution of 3 working conditions, i.e., actual operating voltage condition, equivalent DC voltage condition and equivalent AC voltage condition, are calculated, and the difference and similarity of the electric field distribution under these 3 conditions are compared and analyzed, after which the electric field distribution rules and the insulation structure design ideas for the valve side bushing under actual operating voltage are put forward. The achievements can provide useful reference for the design and operation of the valve side bushing.

In order to evaluate and optimize the seismic performance of ±800 kV UHVDC filter capacitor, a elaborate nolinear finite element model(FEM) is established and the seismic responses of filter capacitor is obtained from time history computing method. Aiming at a ±800 kV UHVDC filter capacitor, it is found that UHV filter capacitor has strong non-linearity and low frequencies and it generates large displacement responses under earthquakes. In addition, the safety factor of hanger insulators for fortification earthquakes doesn’t meet the requirements of relevant codes. Through the analysis on the coefficients of the pretension force and installation angles of bottom insulators. It is concluded that the displacement responses can be reduced by increasing the pretension force in insulators and the maximum axial force of filter capacitor can be adjusted by optimizing the installation angles of bottom insulators, the DC filter can meet the seismic requirements when the installation angle is set as 80 °, the pretension force is set as 40 kN after the specified tension load for hanger insulators is no less than 536 kN.

Commutation failures are prone to occur in the HVDC projects where the inverter station connects to a weak AC system and severely affects the safety of the power grid. It becomes an urgent requirement of these HVDC projects to improve the control strategy of HVDC, thereby suppress the occurrence of commutation failure as well as improve the fault recovery characteristics. In this paper, an additional control strategy is proposed to reduce the duration of commutation failure. In the proposed control strategy, a PI controller is designed to establish the relationship between the DC current rate and the extinction angle, which increases both the extinction angle and the rate of DC current during the fault, thus reduces the duration of commutation failure and improving the recovery characteristics of the DC system after the fault. The validity of the proposed control strategy is verified by the PSCAD simulation of the actual model of Guanyinyan HVDC project.

Compared with traditional AC grid, VSC-DC grid has strong advantages and has attracted great attention in the applications of renewable energy and other multi-energy access. To avoid the contention of voltage control among units of multi-terminal VSC-DC grid, this paper proposes a common DC voltage coordinated control method for multi-terminal VSC-DC grid. The proposed method uses the common DC voltage of multi-terminal VSC-DC grid as the public information source, based on different operational conditions of load units, renewable energy units, energy storage units and auxiliary power supply units, the common DC voltage of multi-terminal VSC-DC grid is controlled within the desired regions by renewable energy units, energy storage units and auxiliary power supply units respectively, then the voltage stability of the multi-terminal VSC-DC grid is well maintained. Finally, the simulation results by Saber software verify that the proposed control method can effectively control the common DC voltage of multi-terminal VSC-DC grid and maintain the balance of the system power.

Current transformer is one of the important equipment in power system, and is widely used in different voltage levels, its primary side is connected to the primary side of power system, and its secondary side is connected to the secondary system. Therefore it is both primary and secondary equipment, once main insulation fault of current transformer occurs, it will directly affect the reliability of power system operation. In this paper, based on a typical main insulation fault of 500 kV SF₆ current transformer, combined with the disassembly of current transformer, a finite element simulation software named ElecNet of Infdytica is used to calculate and analyze the potential distribution and electric field, the process of fault is explained, it is revealed that air gaps within defective basin insulator cause partial discharge for a long time, which results in main insulation failure. The electric field of current transformer under normal working condition is detailedly analyzed, the fault process is revealed. The research achievements will be of great significance to guide the selection of 500 kV SF₆ current transformer, and improve the operation reliability of power system.

To suppress the magnetic interference on grounding system caused by air-core reactors, two kinds of schemes to reduce the induced current of grounding system are proposed, one is to adopt independent secondary grounding body, the other is to adopt radial grounding grid structure. In this paper, the current of secondary cable shielding layer and grid grounding network is measured in a 500 kV substation. According to the reverse-voltage theoretical model and on site experiment results, the effect of adding independent secondary grounding body for shileding layers of different lines is analyzed. Futhermore, a 3D electromagnetic model is built to simulate and compare the anti-interference effect for radial grounding grids. The emulational data and experimental reasults show that by using secondary grounding body, more than half of the induced current can be reduced, and the radial grounding grids under reactor can suppress the magnetic interference effectively.

Nowadays power dispatching center needs to check the trading energy of power plant in monthly market to ensure that the trading energy meets the operation requirements of the actual situation. To solve this problem, a two-stage checking method is proposed in this paper. The first stage is monthly power distribution based on a monthly unit commitment model to confirm the schedule plan for the unit and distribute the monthly power into each day. The second stage is typical day operation simulation based on a daily economic dispatch model to check whether the generation curve of each plant can meet the requirements of power grid security. Based on two-layers optimization theory, the two-stage problem mentioned is iterated repeatedly and solved. This method can check whether the trading result meets the operation requirements and provide a useful method about the maximum trading power of a certain power plant. The validity of the proposed method is verified by a case study in IEEE 30 buses system.

The current compensation mechanism of peak load regulation auxiliary services can not sufficiently mobilize the enthusiasm of thermal power units to participate in deep peak load regulation because of neglecting the differences in thermal power units capacities and holding to single compensation standard. From the view of the influence of subjective and objective factors on peak load regulation, a method of dividing basic and deep peak load regulation considering subjective factors of peak load regulation is put forward to improve the enthusiasm of units with different capacities to participate in deep peak load regulation. Then a deep peak load regulation compensation model considering objective demand and subjective capability is proposed. In the proposed model, the compensation standard can objectively reflect the demand change of peak load regulation and the contribution energy of deep peak load regulation can reflect the differences of peak load regulation capability of units, which is effective for units to participate in deep peak load regulation and improve their capabilities of peak load regulation. The example analysis demonstrates the effectiveness of the compensation model.

Aiming at the high-speed computing demands of multiple periods security check in power systems, combined with the application of distributed computing technology to power systems security and stability analysis, a multi-scheme concurrent computing architecture for dispatching schedule security check is proposed. Computing data generation and security stability assessment with multiple periods of dispatching schedule are running in stages by the optimization of the security check calculation process. Based on multi-scheme concurrent mechanism, asynchronous concurrent opertation of multi-scheme security and stability computing tasks is accomplished. The method can significantly reduce the cycle of the security check of multiple periods dispatching schedule. The applications to actual power grid demonstrate the practicality and validity of the method.

In order to solve the problem of signal missing in heterogeneous model in power system dispatching and operation simulation mirror system, the technical characteristics of data mapping of the heterogeneous model are researched in this paper. And the reason for remote measurement and remote signal missing during the data mapping is also analyzed. Aiming at the sitations of remote signal missing, remote measurement missing for a single branch of a bus node or power grid loop, the data complement methods based on logic derivation including network topology searching, nodal power balance equations and branch loop power equations are addressed. Aiming at the complex siuation of multi-branch data missing, a new data complement method of the weighted least absolute value state estimation based on the independent branch loop power equations and bus node balance equations is proposed. This method has already been applied to the power system dispatching and operation simulation mirror system of CSG.

As the first step to restore power system swiftly after black-out, black-start has became an important topic in the field of power system research. To provide guidance and reference for the study of power system black-start, the latest research achievements on black-start in China and abroad are summarized, and the research progress on the key technologies of black-start are introduced from five aspects, including selection of black-start power source and unit, planning of black-start route, load recovery, and safety verification. The research prospect is discussed, and it is pointed out that implementation of black-start with power source of clean energy, researches on aided decision making technology, making extended black-start schemes, and focusing on black-start implementations are the future developing trend.