Abstract:In this paper, a new method is proposed to evaluate the operation modes of 500/220 kV electromagnetic loop network. From the views of reliability and economy of power grid operation, the bus-bar short-circuit current level, the line load rate, the transformer load rate, the power grid static security, the power grid transient stability and the power grid loss are selected as evaluation indexes. Based on the anticipant curves of each index during actual operation of power grid, evaluation formula combined with threshold is established. To acquire the weight coefficient of each operation index, a new group decision-making theory is adopted. Comparisons of calculation results of an actual example shows that the proposed method is practical and effective.

Abstract:When the penetration of wind power is high, the fluctuations of the output of the wind farm with multipoint accesses becomes disturbance to the power grid. It threats the safety and stability of the power grid. Aimed at the overall volatility and local surge of power flow, a bi-level optimal dispatching approach for grid-connected wind power based on source-grid collaboration and control of conventional units, ESSs and TCSC is proposed. The objectives of the upper and the lower models are to optimize the overall power flow and the key interfaces' power flow, respectively. The methods for solving the upper and the lower models are both the genetic algorithm with multi-elitist preservation method. The simulations on the IEEE 39 test system including wind farms validate the proposed dispatching method.

Abstract:Along with the trends of expansion and intensiveness of operation management system of electric power grid, the monitoring scope of regional power grid dispatching supporting system expanded. The historical data management technology only based on traditional RDB or time series database (TSDB) can't meet operational demand of large-scale regional power grid. The newly developed massive historical data management technology based on TSDB combining with RDB and file system can solve these problems. The paper first introduced the architecture of the management system, then described the key technologies for high-capacity, high-efficiency and high-reliability problems, which is followed by an introduction of intensive application of the technology. The technology has been applied in Suzhou, the biggest city electric grid dispatching supporting system in China. It raised the dispatching level and provided strong technological supports to smart electric grid construction.

Abstract:This paper introduces an accident of voltage-dividing capacitor breakdown in a routine test of 35 kV Capacitive Voltage Transformer (CVT). According to the principle of CVT's measurement, the causes of the fault are analyzed. Some other approaches are adopted to verify our analysis. Preventive measures for similar accidents are provided.

Abstract:The control circuit of switch in cabinet directly affects the operation and the executing of relay protection. Abnormal control circuit would lead to tripping failure, which endangers power grid's security. In this paper, the control circuit of 10 kV handcart switch cabinet and the switching mechanism circuit are analyzed. Also, the reasons of control circuit breaking are summarized, and the methods for inspecting faults in control circuit are proposed. A detailed analysis of the causes and the treatment methods of 10 kV capacitor switch control circuit break in a110 kV substations are provided by using a practical example. This analysis provides a reference for future similar problems.

Abstract:In this paper, based on Dempster-Shafer (D–S) evidence theory, a new bus load forecasting approach is presented. The proposed method will firstly establish the weight extraction model and weight fusion model for BP neural networks, generalized BP neural networks and SVM bus load forecasting models, respectively. Then, by using D–S evidence theory, the weights of three forecasting models are fused. After the extraction of fusion samples of evidence theory by analyzing forecasting data, and multi-fusion result of belief function is taken as the weight of bus load forecasting model, by which the bus load in the future is forecasted. Finally, simulation results provided later show that the proposed method in this paper are more effective and has a higher forecasting accuracy than that by using only one model.

Abstract:The zero sequence over-current protection would clear fault in low resistance ground system. The fault current contains the short circuit and the capacitance current. Therefore, the effects of capacitance current on zero sequence protection of 10 kV line and transformer backup zero sequence protection should be considered, especially for the value setting of definite-time of zero sequence over-current protection. The direction of capacitance current and fault current of 10kV line is investigated. The quantitative effects of single-line ground fault on line zero sequence protection and transformer backup zero sequence protection are analyzed. It provides a reference for coordinating protection settings between transformer backup definite-time of zero sequence protection and 10kV line definite-time of zero sequence protection.

Abstract:In this paper, based on particle swarm optimization algorithm, the expansion planning of power network containing wind power for relieving transmission congestion is investigated. Inertia weights and acceleration coefficients are critical parameters in PSO algorithm. To avoid local optimal solution and to accelerate convergence speed, an improved PSO algorithm with self-adjusting inertia weights and acceleration coefficients is proposed. The simulations on the IEEE 39 power system show that the proposed algorithm significantly reduces computational time to obtain the global optimal solution.

Abstract:The solar energy battery is the core part of photovoltaic generating system, so the photovoltaic battery attracts lots of researchers' attention. This paper analyzed operational characteristic of solar energy battery plate. Simulation models of photovoltaic cells and MPPT are built in PSCAD/EMTDC software. Simulation results show that the output power of photovoltaic cells can track maximum power point well in the condition of light intensity changes and can produce maximum power in different light conditions

Abstract:As an important part of the smart grid, the first-class distribution network and its development are directly related to the access of new energy and the popularization of EV. Combined with the actual development of distribution network, this paper presents the study on the coordinated operation of the new energy power generation and EV charging storage station. Firstly, the coordinated operation adaptability of energy supply between new energy power generation and EV is analyzed. Based on this and compared with existing demonstration project, the coordinated operation mode which can improve the absorptive capacity and realize the overall benefit maximization is proposed. Last, some suggestions are put forward.

Abstract:On the basis of the IEC61850 communication system applied to feeder automation, intelligent access of terminal equipment to the power grid is achieved by using the interchangeability principle. Based on resource definition mechanisms and incentive demand resources matching mechanism, automatic object data matching model is realized with the production resource IP address from GIS system. The established topology model of engineering system achieves object-oriented equipment in the system. The difference between feeder terminal model and distribution master model is eliminated by replacing the SCL model into the CIM model. Through resources determination, associating, topology model updating, resource object connecting and model transforming, intelligent access to the feeder terminal is achieved.

Abstract:Considering the difficulty in current power grid construction, the compression of construction cycle, the more restricted environmental requirement and the increasingly intelligent and fineness of substation equipment, this paper proposes a construction model of distribution-mode smart substation based on the prefabricated cabin. The characteristics of this model is analyzed, and the design scheme is introduced. The smart substation includes two parts: the intelligent primary equipment and prefabricated cabin which integrated with secondary equipment. The two parts are connected with prefabricated cables and prefabricated fiber optic cables. Besides, in this paper, the structure, the inner layout and the wiring and operation environment of prefabricated cabin are discussed. In the end, the concrete implementation of the method is provided. Also, the analysis of technical and economic significance combining with practical engineering applications is presented, which provides reference for future prefabricated cabin based smart substation construction.

Abstract:The calculations related to transient stability analysis and transient stability control are time-consuming and low-efficiency. To deal with these problems, in this paper, the batch calculation of transient stability control for multi-case and multi-fault is realized. This method is based on the SWNT program in PSD-BPA software, the project-case data management, the custom defined data cards and fault file and the automatic identification of system stability. The method significantly improves calculation efficiency.

Abstract:To evaluate distributed network planning scheme effectively, a 3-class evaluation system including technical and economic aspects is established. A catastrophe theory based synthetical assessment on distributed network planning scheme is proposed. The proposed method adopts normalized formula to extract catastrophe progression under the assumption that the state variables near the critical point do not vary continuously. Therefore, it differs from ordinary methods in terms of using indices weights, so that subjective factors are avoided and decision obtained are more objective. Finally, the effectiveness and accuracy of the proposed method is verified by comparing with other methods on an actual distributed network.

Abstract:Combining with the last constructed offshore wind power farm in Jiangsu Province, the selecting principles of integrating voltage level and number of connecting circuits are introduced. The reactive power balance and the court-measures for inner over-voltage of large-scale wind farm connected to the power grid through a long distance transmission line are discussed. Based on an engineering project, a method for reactive compensation capacity calculation for large-scale offshore wind farm is proposed.

Abstract:Single phase adaptive reclosing technology improves the reliability and the stability of the power system. A successful reclosing is depended on quick and automatic extinction of the secondary arc. The factors affecting the secondary arc are recovery voltage and secondary arc current. The paper proposes a method to calculate the accurate recovery voltage of transmission line without series capacitor by using system and line parameters. Then the main factors affecting recovery voltage are detailed discussed. It shows that recovery voltage is related to transmission line voltage rate, transmitted power, conductor spatial arrangement and line parameters. Simulation results from Electro-Magnetic Transient Program (EMTP) validates the proposed method.

Abstract:In the smart substation, data collected from any place is available for the entire substation' is required by data acquisition of merging unit. Therefore, the digital interface of merging units should possess the sampling rate conversion function and meet the demand of differential protection. This paper studies the mechanism of sampling rate conversion with cascade connection of decimation and interpolation. Also, the impacts of sampling rate conversion on differential current of differential protection is analyzed. To reduce group delay of high order Finite Impulse Response (FIR) in sampling rate conversion, a zero phase filtering algorithm is designed. Combining this algorithm with decimation and interpolation algorithm, the data from ECTs with different sampling rates can be converted to the same one. This achieves a unified sampling rate and improves the action speed of differential protection.

Abstract:GDE has been proved to be one effective method for the simulation calculation of the ultrafine particle coalescence situation. Many methods were explored, including the Partition algorithm, the Moment method, the MC method and so on. The initial size distribution of the PM10 was measured using the laser particle size analyzer and the ANDERSON, which provided a theoretical basis for the ultrafine particle coalescence numerical simulation. Using CFD software, the turbulence coalescence model was established. The results were consistent with the literature and experiments, which illustrated the rationality of the turbulence coalescence and arithmetic method effectively.

Abstract:The high temperature corrosion of water wall, the low-temperature corrosion and the deposition of air preheater, and the operating condition of the gas desulfurization system in Nanre 2× 600MW Power Units are analyzed in the paper. It also elaborates the principles of both the high-temperature and low-temperature corrosion. Besides, the harm associated with burning high sulfur coal and the solution measures are presented.

Abstract:In large-scale coal-fired power plants, through reasonably organizing the in-furnace combustion processes, all the boilers are designed to achieve low NOx emission. The combustion debugging and tests on NOx emission characteristic of one 1000 MW ultra-supercritical tower boiler were carried out by optimizing the combustion technology. Based on the test results, the effects of various boiler operating parameters on the NOX emission were analyzed. The obtained conclusions can guide the similar boilers to achieve low NOx emission.

Abstract:With the example of selective catalytic reduction (SCR) denitration technique adopted by domestic thermal power plants, the cost of denitration devices is analyzed in this paper. The top three components of the whole cost are reducing agent, catalyzer, and the depreciation of permanent assets. Based on the cost mentioned above, the denitration electrovalency of coal-fired power plants is estimated. The methods for reducing the cost and enhancing the efficiency of denitration are proposed. The safe precautions for denitration devices are also presented.

Abstract:In this paper, firstly, the main factors influencing the slagging issues within boiler furnace are introduced. Then, the widely adopted methods for monitoring the slagging condition and sootblowing problems are analyzed. Focusing on one 300 MW drum boiler, we proposed a method employing the outlet steam temperature of the low-temperature superheater as the main monitoring parameter for the slagging condition within the furnace. The field test results strongly supported the validity of the proposed method.