The integrated energy system (IES) is developing rapidly. Under the background of “dual carbon” strategy, reducing carbon emission has become a research focus. In this paper, a day-ahead optimal scheduling of IES is presented with comprehensive considering of carbon emission target, constraints and demand response (DR). Firstly, the architecture and strategy of IES based on carbon information flow are analyzed. Secondly, an integrated DR model including electricity, gas, heat and cooling is established by using the transfer and substitution characteristics of demand-side load, considering multi-energy complementarity. Finally, with the objective of minimizing economic cost and carbon emissions, a day-ahead optimal scheduling model of IES considering carbon emission target, constraints and DR is established by adding carbon emission constraints to the existing scheduling constraints. Simulation results show that the method can effectively reduce the economic cost and carbon emissions of the system, improve load distribution in time, and provide an effective means for low-carbon power grid scheduling.

The coordinated operation of “source-grid-load” considering the high dual uncertainties of the high proportion of distributed photovoltaic output and the massive flexible loads is a difficult problem that needs to be solved urgently in the development of new power system. For this reason, a deterministic optimal model for the economic autonomous operation of the transformer area with the goal of minimizing operating costs considering the flexible adjustability and demand response characteristics of active loads is established; Based on this, a robust polyhedral uncertainty set that characterizes source-side and load-side fluctuations is constructed, and an uncertainty optimization model for economic autonomous operation of transformer areas is established. Then, the autonomous uncertainty optimization model is converted into a robust optimization model of decoupling iterative solution to realize the distributed iterative solution by using ADMM algorithm. It can be concluded from simulation and comparison experiments that the solve efficiency of the distributed optimization method that takes into account the dual uncertainty of sources and loads for the economic operation of the transformer area is better than the centralized algorithm and can promote the distributed photovoltaic consumption while reducing the users’ electricity costs.

The integration of a high proportion of renewable energy into an integrated energy system containing electricity, gas and heat loads increases the complexity of system operation and affects the economic efficiency of the system. Therefore, this paper firstly analyses the coupling characteristics of the system source-load equipment and the new energy consumption pattern under the market mechanism, introduces the electricity market bidding mechanism and the two-part tariff for peak load regulation, and constructs a multi-source-load two-layer collaborative optimal allocation model that takes into account the new energy consumption cost with the objective of maximising the annual net revenue and the operational revenue. The results verify the effectiveness and feasibility of the proposed method, which can be used to optimise the allocation of various types of equipment in the system and improve the system operating revenue and the share of renewable energy generation.

In order to improve the efficiency of integrated energy microgrid, considering the user side and energy supply side respectively, a two-level optimization game model between load aggregator and integrated energy microgrid operator based on stackelberg game is established. Firstly, considering the active role of users and the multi-energy complementary characteristics of the user side, the energy consumption behavior of users is analyzed. Secondly, considering the marginal utility of user energy consumption, an optimization model of load aggregators aiming at the maximum user satisfaction is proposed, and the energy purchase plan of load aggregators is formulated. At the same time, the pricing strategy model of integrated energy system operators aiming at maximizing revenue is established, and a reasonable price incentive mechanism is constructed. Then, the double-layer model is transformed into a single-layer model by Karush-Kuhn-Tucker (KKT) conditional transformation, and the original bilinear nonconvex problem is convexly relaxed and solved by McCormick Envelopes method. The simulation results of an example show that this method can promote the interaction between the energy supply side and the user side of the system, improve the energy consumption satisfaction of the user side, and improve the income of the energy supply side of the integrated energy microgrid, which is conducive to the overall development of the integrated energy system.

The combined cooling, heating and power system (CCHP) can be used to realize the cascade utilization of energies and improve the energy utilization efficiency. Focusing on the phenomenon that the traditional self-sufficiency mode is easy to cause insufficient or excess regional energy supply, a method of constructing virtual energy station to coordinate and optimize the energy supply of multiple characteristic complementary regions is proposed. Firstly, the medium and long-term trading volume is signed with the power and natural gas market based on the typical load curve, then the operation strategy for obtaining the maximum revenue of the virtual energy station is determined according to the purchase and sale price of power and gas in the day ahead market. To solve the impact of internal load uncertainty, this paper introduces the downside risk into a two-stage stochastic programming model that maximizes the benefit of virtual energy station, and makes the decision to ensure the minimum benefit by controlling the risk factors. The feasibility and effectiveness of the proposed model are verified through case studies. On the basis of ensuring the energy supply demand of users, the virtual energy station can participate in the day ahead market to obtain considerable benefits. Finally, the benefits under different risk control factors are analyzed, so as to provide reference to decision makers with different risk preferences.

The implementation of National Emission Trading Scheme(National ETS) in China aims to constrain excessive carbon emissions and promote energy conservation. However, it has been a controversial issue which part of electricity market participants should undertake the cost for excessive emission. Power generators are the direct emitters while electricity customers are the underlying drivers of carbon emissions. Different restriction objects in ETS may influence its emission mitigation effect. Therefore, this paper compares the policy impacts of bilateral pricing with unilateral pricing by implementing empirical experiments with the real market data and policy parameters in Guangdong province. The paper proposes carbon-oriented demand response (CDR), takes the arbitrage profit between the electricity market and emission trading markets as one motivator of customers participating DR. Based on different cases simulation, the overall emission mitigation effect and the changes in user behavior in the power market when introducing different sides into carbon market are compared.The paper discovers that under the current electricity market mechanism in China, the power generation pricing cannot fully transfer the carbon emission cost to the customers. Involving the participation of both demand-side and supply-side is more suitable for China to minimize the overall emission.

The penetration rate of renewable energy in the future new power system is increasing day by day. Distributed wind and photovoltaic energy input to the main grid will cause excess power to form a reverse flow in the feeder and increase the line loss of the distribution network. In order to reduce the loss of power transmission and promote the local consumption of new energy, this paper uses a large number of ice storage air conditioning clusters as the carrier to construct a framework for ice storage air conditioning clusters to participate in the microgrid economic dispatching, and analyzes the control advantages and the dispatching process of the ice storage air conditioning during cold storage and release process. Secondly, the uncertainty of microgrid distributed wind and photovoltaic output is modeled based on the scenario method. Considering the microgrid scheduling cost, line loss cost and conditional risk cost under the influence of uncertainty, the optimal scheduling model with the minimum total expected cost and the adjustment capacity and cost constraint set of each equipment in the system are constructed, and the uniqueness of the optimal solution of the model is verified according to the Lagrange multiplier method. The example simulation shows that the stochastic scheduling strategy in this paper can promote the economy of microgrid operation and deal with the risk of uncertainty. The ice storage air conditioning cluster can promote the local consumption of scenery and reduce the network loss caused by power reverse transmission, which is more economical than ordinary air conditioning and lithium battery.

The converter station of the LCC-MMC hybrid UHVDC transmission system with the LCC rectifier and the MMC inverter is formed in series by high and low voltage valve groups. When this system uses two control strategies: “constant current control in LCC converter/constant voltage control in MMC converter” and “constant voltage control in LCC converter/constant eactive power control in MMC converter”, there is a phenomenon that the DC voltage and active power of the high and low valve groups of the LCC rectifier and the MMC inverter are unbalanced. This paper proposes that the unbalanced current between the high and low valve groups and the uncontrollable voltage of valve is the cause of the DC voltage imbalance between the valve groups, and analyzes the mechanism of the unbalance phenomenon. A voltage equalization control strategy using the deviation between the actual voltage of the valve group and the rated voltage is designed, so that the DC voltage between the valve groups can be balanced. Finally, the effectiveness of the proposed voltage equalization control strategy is verified on the PSCAD/EMTDC platform.

The application of half bridge modular multilevel converter (MMC) in DC deicing system has the advantages of low harmonic content, small volume, high economy and reactive power support. In order to meet the ice melting requirements of lines with different lengths and resistivities, a half bridge MMC ice melting system with Buck chopper unit and its cooperative control strategy are proposed to realize the wide range continuous adjustment of DC voltage. Aiming at the different deicing current requirements of DC side, an active control method of MMC bridge arm voltage is proposed to realize the adaptive adjustment of DC outlet voltage. Considering the requirements of AC outlet voltage and the constraint of maximum modulation ratio, the coordination scheme of MMC bridge arm voltage and DC side additional Buck chopper circuit is designed. The wide range of deicing line voltage is realized by controlling the duty cycle of Buck chopper circuit regulation in order to meet the ice melting needs of different lines at the same time to ensure the power quality of the AC side. Finally, a simulation model is built in MATLAB/Simulink to verify the correctness and effectiveness of the proposed cooperative control strategy.

In order to evaluate the influence of component parameter uncertainty on the reliability of HVDC transmission system, this paper presents a reliability interval evaluation method for HVDC transmission system based on affine arithmetic (AA). Firstly, the interval form is used to describe the uncertainty of component reliability parameters, an interval algorithm expression and a reliability interval evaluation model of the HVDC system reliability indices are established. Then, considering that the result of interval arithmetic is too conservative, AA is introduced into the reliability evaluation of HVDC transmission system. Finally, through the analysis of double 12 pulse HVDC transmission system, it is proved that the proposed method can effectively describe the influence of component parameter uncertainty on the reliability evaluation of HVDC transmission system, which can provide a better reference for practical engineering, the weak components of the system can be identified efficiently.

In view of the current lack of debugging means for HVDC protection system, this paper proposes a single device function test method and a distributed system test method for HVDC protection system, and designs a combined/distributed new HVDC test device to realize the above two test methods. The HVDC test device includes management module, power amplifier module, switch input/output module and optical fiber ethernet module, fiber FT3 module, power module, etc.; every/each module includes internal bus interface, general power interface, external fiber interface, through the internal bus interface and general power interface, each module is combined in a chassis to form a combined test device, through the external fiber interface and general power interface to form a distributed test device. Combined test device is easy to carry, easy to store and manage, mainly for the function and performance test of single HVDC protection device, while distributed test device is mainly for the field distributed system test scenario. This flexible combination method not only reduces the cost and volume of test device, but also has rich interfaces and flexible use. Engineering practice shows that the device fully meets the requirements of HVDC protection Requirements of on-site maintenance and operation of maintenance system.

When an HVDC transmission system is fed into a weak AC system, the fault recovery performance of the AC/DC system is poor after receiving AC system faults caused by induce commutation failures of the inverters, and there may be a problem that the AC/DC system cannot resume a stable operation state. This paper investigates the DC control functions that affect the dynamic performance of HVDC transmission systems. Based on the detailed electromagnetic transient simulation model of an actual HVDC project that feeds into a weak AC system, the original DC control parameters suitable for strong receiving AC systems are optimized through the simulation method. Taking the improvement of the maximum transmission power limit of the HVDC system as the evaluation index of the improvement effect, the fault recovery performance of the AC/DC system before and after the control parameters op-timization is compared and analyzed. The simulation results show that the optimization of DC control parameters can significantly improve the fault recovery performance, and it is the method that should be the priority to improve the transmission capacity of DC transmission projects fed into weak AC systems.

Based on the allowable safety current for human body, the maximum allowable values of the safety indexs under the conditions of power frequency short circuit and lightning strike are caculated. Taking two typical designs of grounding device for existing 220 kV urban transmission steel tubular tower as prototypes, the actual values of safety index of grounding device under typical design are obtained by the simulation on CDEGS software. Combined with the actual situation, it is considered that the power frequency step voltage exceeding the standard is the key problem for the safety of grounding devices. A method of replacing part of the vertical grounding electrode with spiral grounding module is proposed to balance the step voltage, and the structure of spiral grounding module is optimized according to the change law of its grounding characteristics with its structural parameters. A design method of combining two typical designs of grounding device for 220 kV urban transmission steel tubular tower with the spiral grounding module is proposed to meet the safety design index, and the optimization scheme of grounding safety design for transmission steel tubular tower is obtained. The research results provide a method reference for the safety design of transmission tower grounding.

Aiming at the low efficiency of manual disaster exploration, and the delay information feedback of back-end analysis using unmanned aerial vehicle in distribution network disaster exploration, an instantaneous detection model is proposed for the collapse of distribution network poles based on improved YOLO-ResNet hybrid neural network. Firstly, generalized intersection over union (GIoU) is introduced to improve the traditional YOLO-V3 algorithm to effectively enhance the accuracy of detecting the main body of poles. Then, ResNet-50 algorithm is used to locate endpoints and center line of poles, and a pole attitude judgment method is proposed to quickly calculate the pole tilt angle. Finally, a portable device for the model mentioned is developed, and the model and device are tested with field collected data. The results show that the overall accuracy of pole pose judgment based on the proposed model is 93.48%, the average power consumption of the portable device is 9 W, which is capable to intelligently analyze and summary the damaging status of the poles on the front end, and the effectiveness of the model and device is verified.

Small defects existing in the production and installation of 10 kV cable accessories are easy to cause failures, so it is of great significance to study effective insulation performance evaluation methods. A comprehensive insulation performance evaluation method considering small defect disturbance is proposed. The precision analysis method of electric field strength is proposed, its accuracy is verified by comparison with the analytical solution. It is confirmed that the electric field strength distortion is the most serious when the small defect is located at the insulation interface in the accessory. Based on the cable accessories from nine different manufacturers, models with small defects on the insulation interface in the accessories are made; Based on the pulse current method, the key parameters of partial discharge of different models with and without defects are measured under the same measurement accuracy; The comprehensive insulation performance is determined by the analytic hierarchy process. The results show that small defects have great influence on the comprehensive insulation performance of cable accessories, which verifies the necessity of considering the ability of accessories to resist small defect disturbance.

The grid-connection of a large number of distributed photovoltaic equipment has transformed the original unidirectional flow power into a bidirectional power flow in low-voltage distribution network, which brings the risk of voltage drop or even instability to the terminal power supply node, and affects safe and reliable power supply. The physical location of distributed photovoltaic is geographically dispersed, and has strong distributed control requirements. The function block technology based on IEC 61499 standard has the characteristics of lightweight and distributed. A droop control algorithm is applied for photovoltaic inverters in a large number of distributed photovoltaic application scenarios, to accomplish the photovoltaic droop control process and hierarchical control in IEC 61499 standard function block platform to meet the needs of distributed control. The communication function block is constructed to realize the co-simulation of the IEC 61499 function block platform and Simulink. The control and regulation effect is verified by the example of distributed photovoltaic islanding grid, which shows that the IEC 61499 standard meets the actual needs of the photovoltaic inverter control process and can be used for photovoltaic equipment to accomplish hierarchical control for application foundation and expansion platform. Co-simulation can effectively verify the control effect of function blocks application and expand application scenarios.