Millisecond-level Source-grid-load Precise Control System and its Key Technologies

There is an increasing amount of new energy power generation being applied in power systems. However, the peak shaving problem faced by the power grid is becoming more and more significant. Large-scale energy storage access to the power grid can assist the power system in peak shaving. Therefore, this paper establishes an energy storage peak shaving model considering carbon footprint cost and establishes a user-side carbon footprint cost model. On this basis, multi-objective optimization is carried out. A multi-objective optimization model of energy storage participating in power grid peak shaving considering carbon footprint is established. The optimization model aims at the optimal PS-VF (Peak Shaving and Valley Filling) effect and the optimal economy of the ESPS (Energy Storage Power Station). The net load variance is used as the evaluation index of the PS-VF effect of the ESPS. By normalizing the multi-objective function, the example analysis is carried out, and the results verify the effectiveness of the model.

In view of the problems that most load forecasting methods are difficult to achieve high-precision data processing in the process of power grid digitization, a digital power grid load forecasting method based on digital twin and improved GRU is proposed. Firstly, the digital power grid model is constructed based on the digital twin technology, and the operation mode of the digital twin power grid is introduced in detail. Then, the time convolution network (TCN) and the gated recurrent unit (GRU) network are fused to design the GRU-TCN prediction model. The high-dimensional data features extracted by TCN are input into the GRU network for learning to enhance the model prediction performance. Finally, the GRU-TCN model is applied to the load forecasting of digital twin power grid, and the high-precision forecasting results are obtained. The experimental results based on the simulation platform show that the proposed method prediction results root mean square error is 28.428KW, and mean absolute percentage error values is 2.161%, which prediction effect is good.

As a modern power grid that integrates advanced communication technology, sensor measurement technology, and intelligent control technology, the smart grid has good economy, reliability, and stability. Building a strong smart grid has important strategic significance for developing the national economy and improving Comprehensive National Power. The balance of electricity supply and demand, as a physical feature of the power system, determines the energy matching relationship between generation and consumption. Unreasonable power generation may lead to unmet electricity demand, as well as excess electricity and waste of resources. The energy storage has solved the problem of imbalance between supply and demand in most environments. The energy storage equipment provides a buffer space for electric energy, effectively adjusts the time unevenness of power grid load, realizes peak shaving and valley filling, and reduces the operation cost of the power grid. Taking the aboveground energy storage power station as the research object, the 3-D unsteady model of the small and medium-sized compressed energy storage system was established by using the FLUENT simulation software, and the correctness was verified through experimental methods. The influence of different environmental temperatures, chamber inflation flow rate, the thermodynamic characteristics of the surface condition and working chamber of the and energy storage were studied. The results show that the environmental temperature and expansion flow of oil storage chamber have important effects on its thermodynamic characteristics, while the surface conditions of oil storage chamber wall have little effect on its thermodynamic characteristics.

A novel adaptive neural network-based fault-tolerant control scheme is proposed for six degree-of-freedom nonlinear helicopter dynamic. The proposed approach can detect and mitigate actuators and sensors’ faults in real time. An adaptive observer-based on neural network (NN) and extended Kalman filter (EKF) is designed, which incorporates the helicopter’s dynamic model to detect faults in the actuators and navigation sensors. Based on the detected faults, an active fault-tolerant controller, including three loops of dynamic inversion, is designed to compensate for the occurred faults in real time. The simulation results showed that the proposed approach is able to detect and mitigate different types of faults on the helicopter actuators, and the helicopter tracks the desired trajectory without any interruption.

In the summer peak load operation mode of the interconnected power grid which is integrated with HVDC transmission lines from Central China power grid to East China power grid, security and stability emergency control strategies based on generator shedding and EDCPS (Emergency DC Power Support) are studied to cope with system instability caused by Tuanlin-Fengjing DC line unipolar block fault. Simulation results show that interconnected system cannot maintain the transient stability effectively by using EDCPS only. A coordinated control strategy which combines generator shedding with EDCPS is proposed to reduce the number of generators to be shed and ensure the transient stability. Through optimizing EDCPS which two or more HVDC lines participate in, an optimal coordinated control strategy is proposed. Simulation results present that the strategy which combines GC shedding with Longzheng DC bipolar supporting is the optimal strategy.

Loading elevator is one of the important equipment for refueling system. The refueling process of the sodium-cooled fast reactor is sealed and the equipment for refueling process is complicated and in large quantity. It is necessary to research and develop a set of high-accuracy and high-reliability control system to ensure loading elevator for the refueling process can operate safely and reliably. This article illustrates and describes loading elevator’s control system design detail. For meet the requirement that the positioning deviation is limited to ±5mm, this control system hardware for loading elevator adopts the advanced digital AC server to position the equipment. Compared with the traditional PLC control method, it has the advantages of high positioning accuracy, simple commissioning process and stable operation. Meanwhile, the multi-fault detection logic is used for fault detection. Though acquire real-time data, the fault logic transfers protection signals and interlocking signals to DCS. This fault logic can ensure that when the equipment operates abnormally, it can detect the fault in real time and stop the motor to ensure the safety of the equipment and components. The control system design plan has been applied in the loading elevator test bench safely and reliably for many times, which proves that it can realize the function of equipment monitoring and control, and also the positioning accuracy can meet all requirements.

Soil compaction is an important procedure of precision seeding operation. In this paper, a precise downforce control system based on fuzzy PID was proposed in order to improve the quality of the soil compaction and the accuracy of setting working parameters. The conventional mechanism of seeders for soil compaction was optimised. The compressing spring of the compaction mechanism was replaced by a linear motor, which is actively controlled to adjust downforce in real time. A force sensor was connected in series with the linear motor to detect the actual downforce from a press wheel acting on soil. The detected downforce was employed as feedback for the fuzzy PID model. A slave real-time control system was constructed by using an STM32 microcontroller. A user interface was designed for the portable master computer system based on the ForLinx embedded platform to facilitate the setting of target downforce and display the actual downforce in real time. Meanwhile, it was able to adjust the system for different operating requirements, such as soil stiffness, moisture, and crop species. Experiments were conducted on a soil bin, and the results indicated that the active control system has better performance than the conventional passive system in downforce control. The downforce was stable with a variance less than 2.6% under different conditions, and it was 8.11% less than the conventional passive system.

Under the background of large‐scale development and utilization of clean energy, there are serious security and stability risks and load balance problems in power grids with high penetration of clean energy and high portion of external power supply. Therefore, Jiangsu Electric Power Company has started the construction of the millisecond accurate load control system (MALCS). In this article, the theoretical basis of the MALCS is introduced from several aspects: the interruptible load, steady state, and transient state control technique of large‐scale load. On this basis, the authors put forward the overall architecture, transmission channel structure, and control strategy of the MALCS. Subsequently, this article introduces the first‐phase and the second‐phase projects of MALCS construction in Jiangsu power grid, and the actual load‐shedding test of Jiangsu MALCS. The results of the actual test show that the overall motion time of the Jiangsu MALCS meets the design requirements, and the MALCS can offer an effective frequency support to Jiangsu and East China Power Grid in case of severe failures. Finally, this article summarises the experience of MALCS construction, introduces the expansion plan of MALCS, and forecasts the future development direction and application of the system.

With the increasing proportion of wind power integration, the effect on the stability of the system power angle cannot be ignored. In this paper, based on the different power characteristics of direct-drive wind generators before a fault and after its clearance, the system model of the receiving-end grid with thermal units replaced by wind turbines is simplified. The influence of the increase in the replacement ratio of wind power in the receiving-end grid on the transfer impedance between the sending end and receiving end is analyzed. Based on the equal area rule, the influence of the replacement ratio k within the receiving-end grid, power grid operation mode, and wind power integration point on the system power angle stability is analyzed. It is concluded that the stability of the system’s power angle will first get better and then deteriorate with the increase in the replacement ratio of wind power, the system can bear a larger proportion of wind turbines under the low-load operation mode, and the system’s power angle of the replacement of wind power with equal capacity in the load center region is relatively better. The aforementioned conclusions are verified by simulation with real data from a bulk power system in China. Therefore, the method and conclusion can also be used to study the power angle stability of other large-scale power grids.

Interruptible load (IL) management as an important component of demand-side management in electricity market affects much the safe and economic operation of the power systems. The cost-benefit of interruptible load participants is analyzed in this paper. The discrete customer category is proposed to indicate the expected compensation for the blackout. This paper presents a model of IL contract, in which the objective function is the minimum compensation cost paid by the power company. The benefits of the power company and the customer are both considered as the restrictions of the model. The actual system examples show the validity of the proposed model.

With the rapid development of energy storage technology, more and more energy storage systems are connected to the large power grid. Therefore, how to improve the safety, reliability and stability of the grid-connected operation of energy storage power stations is the most important. Based on this background, this paper proposes the research on energy management and control methods of large-scale energy storage power station. First of all, the operating cost model of the energy storage system is established by comprehensively considering its life-cycle operation characteristics. Secondly, according to the spatial and temporal distribution characteristics of distributed power supply and load, the energy storage regulation technology based on dynamic safety margin is proposed. Finally, according to the set dynamic safety margin of energy storage system, the energy management method of energy storage power station based on risk correction control is proposed. An example is given to verify that the energy management method proposed in this paper has the following characteristics: it can effectively evaluate the system energy supply sufficiency and realize the accuracy of system regulation.

This paper puts forward the planning and configuration principle of the battery energy storage station(BESS) of the urban secure power grid, and establishes the full-life cycle economic model of the BESS based on the configuration requirements in urban secure power grid for the emergency power supply. Taking the maximum annual equivalent income as the objective function, an economic allocation model of the capacity of BESS for urban secure power grid based on improved particle swarm optimization algorithm(IPSO) was established to achieve the economic optimization of the capacity arrangement of energy storage power station while meeting the important load holding of the city under the disaster scenario of reliable support. At the same time, a reliability analysis model for energy storage capacity configuration results considering the impact of disasters is established to support the reasonable selection. Finally, the scheme comparison and optimization design are carried out based on the actual scenario of an urban secure power grid.

With the in-depth development of smart grid, renewable energy, such as wind power, will be an important source of electrical energy, the proportion of renewable resources increase rapidly. Serious problems emerged with large-scale wind power integrating to power grid. The integration of wind generation imports variability and uncertainty to system operation and control. Control center must consider this variability and uncertainty to dispatch economically. Fortunately, there will be many electric vehicles in smart grid. With the popularization of electric vehicles, charging stations and electric vehicle battery swap stations will be increasing rapidly. Battery swap stations can be regarded as energy storage power stations, which can be used to stabilize the wind power output variability and uncertainty. In this paper, new economic dispatch model considering wind power and electric vehicle battery swap stations is proposed, the Particle Swarm Optimization (PSO) method and prior priority way are adopted to solve this model. The algorithm based on MATLAB 6.5 is developed. The correctness and effectiveness of the model and algorithm are verified using test system.

To ensure the safe and stable operation of the power system in the power market environment, a transaction model of power reserve ancillary services oriented to interruptible loads is constructed. By analyzing the benefits of interruptible users and power grid enterprises, a transaction model of interruptible load is established based on it. After obtaining the value of the minimum cost of power system to purchase interruptible load, the capacity cost, opportunity cost and standby use cost of power reserve are calculated respectively. The objective function of auxiliary power reserve service transaction model with interruptible load is established and the constraint conditions are set, and then the transaction result of auxiliary power reserve service is obtained by solving the objective function of the model. The experimental results show that the model can effectively calculate the power interruption compensation price of user interruptible load, and obtain the interruptible load transaction results according to the rapid capacity quotation, power quotation, etc. At the same time, the model has the lowest cost of reserve capacity and reserve use cost in a certain period of time, and the application effect is good.

Existing methods for structural health monitoring pose a formidable challenge to real timeimplementation due to the significantly large computational loads. The proposed algorithmis suitable for online applications because it maintains good pattern recognition capabilitieswhile possessing a computationally compact network topology. This study employs thecomputational efficiency of single layer radial basis function (RBF) approximaters to createa subspace capable of isolating faults in multi-degree of freedom systems whichinvolve coupled and uncoupled stiffness changes in real time. The RBF networktransforms the displacement–time history of the varying plant into a decoupled outputspace which is then compared to a baseline healthy observer which undergoes thesame decoupling transformation. The online comparison of the output of the timevarying plant and the healthy observer in a decoupled subspace comprises theobserver based error function. The error function is shown to not only detect theexistence of faults, but also isolate these faults in real time in the presence of baseexcitation. The method is validated for systems that experience earthquake induceddamage, as well as an experimental system using a semi-active independent variablestiffness device which is capable of varying system stiffness in real time. By simplyobserving the displacement–time history responses, the RBF augmented observerformulation is capable identifying changes in the stiffness at each degree of freedom.