With the rapid development of West-to-East power transmission and high voltage direct current (HVDC) technique, the impact of HVDC transmission line on oil-gas pipeline becomes increasingly severe. Researches have shown that the grounding current at DC grounding electrode of HVDC transmission line will generate interference potential on pipelines which leads to operational risks. To guarantee safe operation of oil-gas pipeline, this paper proposes a novel coordination control strategy of HVDC monopole block with grounding current constraint. Aiming at minimizing the change of overall generation output and adding fast-decreasing grounding current as constraint, the HVDC monopole block situation is modelled as non-linear programming and solved by infeasible interior point algorithm. The proposed method is verified on HVDC models of China Southern Power Grid in online open-loop circumstances and effectiveness of the algorithm is demonstrated.

In order to reduce the risks concerning system safety and stability brought about by AC/DC interactions, Guangdong Power Grid has taken such measures as adjusting grid structure, deploying dynamic reactive power compensation, and optimizing grid operation mode, etc. In this paper, system stability analysis is carried out before and after refurbishment of conventional HVDCs feeding into the Pearl River Delta region. The results show that VSC-based refurbishment of conventional HVDC can improve the stability of the system to a certain extent, but the improvements are not significant. From the perspective of system stability improvement only, the necessity for VSC-based HVDC refurbishment is not justified. This paper can help to fully appreciate the potential of VSC-based HVDC refurbishment to improve system stability, and provide a good research foundation to further explore the necessity and system scheme of VSC-based refurbishment of conventional HVDCs in Pearl River Delta and Yangtze River Delta power grids. At the same time, this paper provides valuable reference to solve the problems arising from AC/DC system interactions in load center grids with multiple DC infeed.

In order to prevent events which are similar to Brazil "3·21" blackout, this paper analyzes the risk of losing voltage of the converter which is disconnected to AC bus, makes a detailed consideration on 3 conditions which can lead to voltage losing or no AC filter operation. These 3 conditions include all the transmission lines break, the breakers beside the transformer in the same bay break and AC fault. And then this paper proposes a plan to srtengthen the trip function in which converter group will trip after losing connection to all AC buses. At last, simulation verifies that this trip function can stop the converter’s operation and send out converter block signal in time when converters disconnect with AC bus and avoid the operation delay of the security and stability control system because of the receiving delay of the converter block signal. And this new trip funtion has been deployed and verified in field and promotes the capacity and the security of China Southern Grid Power System operation.

The hidden dangers of logic and electrical design in the realization of reactor power control (RPC) function in project are analyzed. Aiming at the lack of monitoring function for the AC filter (ACF) switching anomaly and parameter anomaly without judgment logic in RPC, a monitoring method of RPC is proposed. The monitoring method conducts logical judgement during initiation, entering normal operation program or fault calculation program. It can realize the functions of abnormal switching analysis and judgment of ACF switching status, validity check of AC voltage, validity check of reactive power, oscillation locking of RPC, etc. Some of the functions are applied in engineering.

Composite cross-arms have been used in 35—1 000 kV transmission lines. However the researches on lightning protection performance of the composite cross arm tower are less. Thus, voltage/time curve for 500 kV transmission line tower with composite cross-arm are measured under positive and negative lightning impulses at the Kunming National Engineering Laboratory for UHV Engineering Technology. Flashover criterions of composite cross-arm are obtained. According to the parameters of actual double-circuit transmission line tower with composite cross-arm, electromagnetic transient model of double-circuit transmission lines has been established. Lightning withstand level of back-flashover and shielding strike for double-circuit transmission lines on the same tower with composite cross-arm are calculated using the improved flashover criterion. The results show that the calculated back-flashover lightning withstand level of composite cross-arm tower is about 4% higher than it of conventional tower with the same parameters. The shielding failure lightning withstand level of composite cross-arm tower and conventional tower are similar. Based on the voltage/time curve experimental results, the coefficient k and E₀ for the positive velocity of the leader formula of composite cross-arm are modified to 0.50×10^-6 m²/(V²·s) and 600 kV/m respectively. and the coefficient k and E₀ for negative velocity of the leader formula are modified to 0.55×10^-6 m²/(V²·s) and 650 kV/m respectively. The improved leader propagation models are suitable for research of lightning performance of transmission line tower with composite cross-arm.

In this paper, experiments are carried out in a 4 m rod-plate air gap under positive and negative lightning impulses. High-speed images of leader development process are captured by using a high-speed camera. Based on the experiment results, the relationship between axial velocities of positive and negative leader and leader position are measured. Moreover, the distribution of the number of leader branches and the angle of leader branches are statistically analyzed. The experimental results show that the axial velocity of positive leaders is positively correlated with the voltage amplitude, while the negative-lead axial velocity is not significantly related to the voltage. In addition, the positive and negative axial velocities increase with the distance from the electrode tip. However, the axial velocity of positive leaders tends to be stable within 1.2 m from the end of the electrode. Moreover, two branches account for 91.8% in the leader branching phenomena, and three or four branches are observed in a few cases. Angles of positive branches and negative branches approximate respectively a lognormal distribution with average values of 44.9 ° and 45.3 °.

Aiming at the trippings caused by bird on 110 kV transmission lines in the eastern part of Inner Mongolia, the characteristics of the bird’s droppings flashover and the improvement of the bird-proof device are studied. A bird droppings flashover simulation and test platform is set up to study the influence of the path of bird droppings on the flashover probability of insulator. The test result shows that the closer the bird’s droppings path is to the wire, the longer the critical flashover distance will be, it is considered that the flashover range of the insulator is not circular, but an elliptical shape with its major axis extends along the wire. Finally, the shape and size of the bird-proof cover are improved based on the “drainage” concept and the drainage groove is added. The results from comparative tests show that no flashover occurred to the new type of bird-proof cover, and the effectiveness of the cover is verified.

Severe icing on transmission lines will cause serious losses to the power grid. This paper studies how to use wind power, photovoltaic power generation, biological power generation and energy storage devices in distribution network to realize over-current ice-melting, and puts forward a method of load allocation using energy storage devices; uses flexible switches in distribution network to transfer power flow and generate reactive power to realize over-current ice-melting in distribution network. Simulation results show the effectiveness of the proposed method.

Based on the China Southern Power Grid system, the propagation characteristics of electromechanical disturbance in the actual large power grid are studied. The time-space distribution characteristics of power system frequency are analyzed, and the estimation method of the disturbance propagation velocity is given. The PSD-BPA electromechanical transient simulation program is used to simulate the frequency response characteristics of power system when the generator tripping occurs at different locations, and the time and speed of the disturbance propagation to each observation point are estimated. The propagation characteristics of the disturbance in the actual large power grid are obtained through comparative analysis. Aiming at the pure DC connected asynchronous interconnected power grid, the frequency response characteristics of power grid and the influence of the receiving-end power grid disturbance on the sending-end power grid are studied, and the mechanism of DC system transmission disturbance is discussed. Finally, the conclusions drawn from the work of this paper are summarized, which will provide reference for the study of wide-area stability control of interconnected large power grids based on electromechanical wave theory.

Along with the construction of southern regional electricity spot market, the development of a technical support system is in progress. Due to the special features of southern regional electricity spot market, it is a necessity to customize the market clearing module in the technical support system. This paper gave an in-depth analysis on the characteristics of southern regional electricity spot market, presented two technical challenges on designing the market clearing logic and computation engine, and proposed solutions respectively. This paper aims to provide a reference for the development of the market clearing module in the technical support system.

The Japanese power market experienced five reforms before and after. The latest round of power reforms has transformed the power system vulnerability and the irrationality of electricity prices highlighted by the Fukushima accident. At present, the Japanese electricity market has been fully marketized, and the feed-in tariff(FIT) system for renewable energy has become more mature. At the same time, in the context of the energy Internet, Japan has actively promoted demand response (DR) and virtual power plant (VPP) development. In the future, Japan will further build a base market, a capacity market, and a non-fossil value trading market to enrich market trading mechanisms. The process of building the Japanese electricity market has many similarities with China. It aims to promote the opening of the power-sales side, and to study its reform process, the status quo of the power system and the future planning route. It has important reference significance for the current construction of China’s electricity market.

With the rapid growth of wind power penetration, the randomness and volatility of the system are significantly enhanced, which may lead to a great challenge to the optimization of the system’s operation. Power flow calculation is the basis of system operation optimization, but it is difficult to obtain uncertain power flow solutions by deterministic power flow calculation. In this paper, rectangular interval power flow (RIPF) model without Chebyshev approximation is firstly proposed, which narrowes the range of the voltage phase angle of the node and the active power of the branch. Meanwhile, by using the polar interval power flow (PIPF) model based on affine arithmetic, the node voltage amplitude interval can be obtained effectively. Finally, a mixed interval power flow (MIPF) is proposed to obtain bounds of power flow incorporating uncertain wind power generation and loads, and it combines merits of RIPF and PIPF, and greatly improves the accuracy of interval power flow calculation. IEEE 30, IEEE 118 and IEEE 300 are used to verify the effectiveness of the proposed method.