## Automation of Electric Power Systems

**Competent Authorities：**State Grid Corporation of China

**Sponsored by：**State Grid Electric Power Research Institute/NARI Group Corporation

**Publisher：**State Grid Electric Power Research Institute Press

**Journal Tags：**Ei，Scopus，INSPEC，CSA，CAS，AJ，JST，Google Scholar，CSAD-C，CSPD，CSCD，CCJAD，CAJCED

**Period：**Semimonthly Publication**Editor in Chief：**XUE Yusheng

**Language：**Chinese**Release Date：**Feb，1977

**Description**

Automation of Electric Power Systems （AEPS），started publication since 1977，has been one of the core periodicals of Ei since 1999 and has been indexed in 14 famous domestic and overseas searching databases. The authoritative data from Google scholar H5, SCImago Journal Rank, CiteScore metrics from Scopus, etc. show that AEPS is always among the best Chinese academic journals.

Also, AEPS is one of the journals with the highest impact factor for years in the field of electric power in China.

**Abtract:**

Security and stability control (SSC) system or special protection system (SPS) is an important means to ensure the safe operation of power grid. In view of the insufficiency that the current open-loop testing method cannot fully test the SSC system on-site, a remote real-time closed-loop test method is proposed. The solutions of key techniques such as information interaction, remote communication and signal conversion in remote test system are studied. Then the platform architecture and standard interface of the remote test system are designed. A remote test platform for SSC system is developed, and there application modes of the platform is deeply analyzed. Finally, taking SSC system of Yunnan AC power outgoing grid as pilot application, experiment of two substations on-site is carried out. The results in practical project further prove the effectiveness of the method presented in this paper.

**Abtract:**

In view of the operational risks and faults in the construction process of HVDC transmission, this paper takes the common grounding faults on the AC side as the problem orientation, to explore the optimization design method of reactive power compensation equipment (SVC) and its new control strategy to improve the HVDC transmission system. It resists the ability of follow-up commutation failure to ensure the stability of the transmission system in grounding fault. The comparison between theoretical analysis and results shows that the voltage drops of the commutated busbar when the fault is used as the basis for judging the capacity of the FC capacitor group and the inductor in the TCR, and the logic of the FC switching and TCR firing angle in the reactive power compensation process. Optimized control can not only effectively resist the risk of follow-up commutation failure, but also solve the voltage “reverse adjustment” in the SVC compensation process.

**Abtract:**

The harmonic characteristics of the synchronous condenser using the static frequency converter (SFC) starting sys-tem are calculated and analyzed, and the influence of the frequency conversion characteristics and harmonic charac-teristics on the starting protection is discussed. In order to filter out the main harmonics in the variable frequency state and increase the calculation accuracy of the synchronous condenser starting protection, an improved fixed fre-quency sampling variable data window discrete Fourier transform (FFSVDW-DFT) algorithm is proposed in this paper. The algorithm compensates for the inherent error when fs/f0 (sampling frequency/system frequency) is a non-integer, and optimize the number of points of the Fourier algorithm adaptively in each cycle according to the current system frequency. At the same time, the fitted function is adopted to calculate the sine and cosine coefficient table in real time. On this basis, the synchronous condenser starting protection is improved and the action equation is given. The improved starting protection algorithm is experimentally verified on the protection device. The results show that the starting protection using the improved FFSVDW-DFT algorithm has high precision. The fundamental component during the fault can be accurately calculated under the variable frequency condition. In addition, the peak-to-peak algorithm is used for the differential start calculation in the proposed starting protection method by combing with the improved FFSVDW-DFT algorithm for the differential action calculation. Thus, the reliability and rapidity of the protection can be both ensured.

**Abtract:**

Large-scale cascading accidents can be caused by overload of transmission section. Using reasonable and effective pro-tection and control measures to reduce the power pressure of transmission section can avoid the occurrence of malig-nant accidents, which has important sense to the safe operation of power system. Aiming at the overload of transmis-sion section, a double-objective progressive protection and control optimization model and the corresponding coordi-nation strategy are proposed in this paper. The overload protection can be used as a kind of mean to change network structure. It is cooperated with the emergency control resources to obtain a better adjustment effect. Firstly, based on the power flow tracking method, the source-load transmission paths in the power system are found. The source-load paths are taken as the basic adjustment units, and the operations of overload protections are introduced as adjustment parameters. Two-layer optimization objectives are constructed: reducing the load shedding amount is the objective in the first layer, and improving the security of the system is the objective in the second layer. The nested optimization algorithm is used to solve the problem gradually. On the premise of power within safety constraints, the strategy pro-posed in this paper can optimize the adjustments of generators and loads and the operation conditions of overload protections. Results of simulation can verify the effectiveness of the proposed method.

**Abtract:**

In order to solve the problem of optimal scheduling caused by conflicts of independent optimized scheduling targets between each electric vehicle aggregator (EVA) after the large-scale electric vehicle (EV) connected to the grid, a large-scale EV real-time scheduling model based on dynamic non-cooperative game considering the interests of EVA is proposed. Firstly, the cluster equivalent model of large-scale EV is constructed and the interest relationship of each EVA under dynamic electricity price mechanism is analyzed. Then the complete potential game theory is used to prove the existence of the unique nash equilibrium solution of the game model and the solution is derived. Finally, a real-time distributed algorithm based on the alternating direction multiplier method is proposed to solve the real-time decision problem of each EVA. The simulation results show that the model can effectively perform peak load shifting and reduce the charging cost of EVAs. At the same time, it is proved that the proposed model is more suitable for real-time large-scale electric vehicle charging optimal scheduling from the optimization results, computing time and protection of user privacy.

**Abtract:**

As the scale of power grid of China continues to expand and the operation characteristics become increasingly complex, the complexity of dispatching and control business of power grid and the burden of dispatchers are increasing. According to the real-time dispatching and control business of power grid, this paper designs an overall architecture of robotic dispatcher for power grid. The design ideas of five functional modules such as intelligent learning, intelligent decision-making, intelligent monitoring, intelligent execution and intelligent interaction are elaborated. Then the corresponding key technologies are described. The six types of application scenarios of dispatching and control are given.

**Abtract:**

Energy Internet is a new type of ecological energy system regarding electric energy as the center, realizing multi-energy coordination, consumption synergy, centralized or distributed coordination, and extensive participation of the public, in which the main performance is the strong integration of the smart grid and ubiquitous electric power internet of things. But the ubiquitous electric power internet of things is just in its infancy and is a key step in the construction of Energy Internet. The construction of ubiquitous electric power internet of things has obvious positive significance for improving user experience, improving the operation level of the power grid, promoting new energy consumption and cultivating emerging businesses. This paper summarizes the overview of the internet of things, the characteristics of ubiquitous electric power internet of things, the key technologies supporting ubiquitous power internet of things and the typical application scenarios. Finally, the challenges in the development of ubiquitous power internet of things is analyzed and prospected.

**Abtract:**

This paper analyzes the time evolution of oscillation energy based on the trajectory modes decoupled in state space and the swings divided in time domain. The trajectory of multi-machine system, which is non-harmonic oscillation, can be mapped into a series of trajectories for time-varying image system through the complementary-cluster center-of-inertial relative-motion(CCCOI-RM)transform, so the oscillation behavior of the multi-machine system is described by the oscillation energy variation of the successive swing. Besides, the non-conservative can be quantified through analyzing the time-space variation of the oscillation energy on the force-position plane. In this paper, the kinetic energy at the dynamic center point(DCP)and the potential energy at the far end point(FEP)are both used to reflect the oscillation energy in the past half swing. Therefore, the sequence of them can reflect the time-varying characteristic of the spatial oscillation mode. After that, through theoretical analysis and numerical simulation, the consistency between the trajectory swing energy sequence and the eigenvalue system is proved when they are used to describe the oscillation behavior of Hamilton one machine infinite-bus(H-OMIB), but the trajectory swing energy sequence can also be used to overcome many defects of the eigenvalue in the non H-OMIB or general multi-machine system.

**Abtract:**

Concentrating solar power(CSP)generation system can well cope with the randomness and intermittence of solar power, which provides a new approach to exploit large-scale renewable energy. There are no unit startup constraints in the existing model, which may lead to infeasible operation schedule. For this problem, this paper analyzes the heat accumulation process during startup of CSP units and develops a CSP operation model considering startup heat constraints. It can describe the operation characteristics of CSP units more precisely. The optimal operation of CSP units is also studied based on the above model. Example analysis is conducted on the modified IEEE-RTS79 system. The results show that the proposed model is correct and effective, and can avoid the occurrence of unfeasible startup schemes. Also, further sensitivity analysis reveals the benefits of CSP units in reducing production costs and promoting accommodation of other renewable energy and its influencing factors.

**Abtract:**

The forecasting error of photovoltaic(PV)output is difficult to avoid and cannot be ignored. The accurate description of the forecasting error distribution is beneficial to the optimal dispatch and stable operation of the power system. The correlation between the forecasting error distribution and influencing factors is analyzed, and a probabilistic model of the PV output forecasting error based on numerical characteristic clustering is proposed. The whole level of forecasting errors will be classified through the fuzzy C-means clustering and the classification on the output forecasting will be conducted according to its numerical characteristics. A general Gauss mixed model available to estimate error distribution is established. Considering the influences of meteorological factors and numerical characteristics on forecasting errors, the model could estimate forecasting errors at different times and produce the confidence interval of error distribution. At the same time, the proposed model is free from the influences brought by different forecasting algorithms and the geographic information of PV power station. Based on the historical data of PV systems in Belgium and Northwest China, analysis results show that the skewness, multi-peak and kurtosis diversity of PV power forecasting error distribution can be described by the proposed model more accurately compared with other distribution models, which can be used to describe the forecasting error distribution of day-ahead PV power in different situations.

## Editors Recommend

**Abtract:**

Energy Internet is a new type of ecological energy system regarding electric energy as the center, realizing multi-energy coordination, consumption synergy, centralized or distributed coordination, and extensive participation of the public, in which the main performance is the strong integration of the smart grid and ubiquitous electric power internet of things. But the ubiquitous electric power internet of things is just in its infancy and is a key step in the construction of Energy Internet. The construction of ubiquitous electric power internet of things has obvious positive significance for improving user experience, improving the operation level of the power grid, promoting new energy consumption and cultivating emerging businesses. This paper summarizes the overview of the internet of things, the characteristics of ubiquitous electric power internet of things, the key technologies supporting ubiquitous power internet of things and the typical application scenarios. Finally, the challenges in the development of ubiquitous power internet of things is analyzed and prospected.

**Abtract:**

This paper analyzes the time evolution of oscillation energy based on the trajectory modes decoupled in state space and the swings divided in time domain. The trajectory of multi-machine system, which is non-harmonic oscillation, can be mapped into a series of trajectories for time-varying image system through the complementary-cluster center-of-inertial relative-motion(CCCOI-RM)transform, so the oscillation behavior of the multi-machine system is described by the oscillation energy variation of the successive swing. Besides, the non-conservative can be quantified through analyzing the time-space variation of the oscillation energy on the force-position plane. In this paper, the kinetic energy at the dynamic center point(DCP)and the potential energy at the far end point(FEP)are both used to reflect the oscillation energy in the past half swing. Therefore, the sequence of them can reflect the time-varying characteristic of the spatial oscillation mode. After that, through theoretical analysis and numerical simulation, the consistency between the trajectory swing energy sequence and the eigenvalue system is proved when they are used to describe the oscillation behavior of Hamilton one machine infinite-bus(H-OMIB), but the trajectory swing energy sequence can also be used to overcome many defects of the eigenvalue in the non H-OMIB or general multi-machine system.

**Abtract:**

As the scale of power grid of China continues to expand and the operation characteristics become increasingly complex, the complexity of dispatching and control business of power grid and the burden of dispatchers are increasing. According to the real-time dispatching and control business of power grid, this paper designs an overall architecture of robotic dispatcher for power grid. The design ideas of five functional modules such as intelligent learning, intelligent decision-making, intelligent monitoring, intelligent execution and intelligent interaction are elaborated. Then the corresponding key technologies are described. The six types of application scenarios of dispatching and control are given.

**Abtract:**

The equivalent load impedance of power converter has an influence on the characteristic analysis of bidirectional wireless power transfer(BWPT)system. So the calculation of equivalent load impedance is of great significance. Firstly, this paper builds a model of BWPT system with bidirectional power converters and LCC compensation networks. And the equivalent circuit of the power converter working in the rectification mode is established. Then, the equivalent circuit rectification operation is analyzed. Furthermore, the calculation method of equivalent load impedance of bidirectional power converters is derived. Finally, a test platform is developed to verify the proposed model and method. The result shows that, when the bidirectional power converter operates in the rectification mode, its equivalent impedance includes resistance and reactance parts, and both of them are related to the parallel capacitance of switch devices, compensation inductance and system load. The proposed method can effectively calculate the equivalent load impedance, which can contribute to accurately analyze the system characteristics.

**Abtract:**

This paper reveals the similarities and differences between the view of the complementary-cluster inter-group energy and the sinusoidal amplitude of characteristic frequency in power system oscillation behavior analysis. It is strictly proved that they are consistent in the Hamilton one-machine infinite-bus(H-OMIB)system. However, the nonlinear factors may cause large errors to the linear analysis. Besides, the time-varying factors and inherently nonlinear factors such as saturation may make the equilibrium point eigenvalue method completely invalid. In order to overcome these difficulties, this paper describes the oscillation characteristic of the complex disturbed system from the view of complementary-cluster inter-group energy. For the multi-machine system, the trajectories can be mapped into a series of time-varying image system trajectory through complementary-clusters center-of-inertial relative-motion(CCCOI-RM)transform. Then, the oscillation behavior of the original multi-machine system is reflected by the oscillation energy of the image systems including the time-varying nonlinear oscillation with multi-frequency.