This study analyzed the dissolved organic matter (DOM) released by adsorbent during wastewater treatment. It was found that the adsorption method resulted in an organic removal efficiency of over 97% for coal-to-olefi...
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Methanol-to-olefin (MTO) is a typical example of the new coal chemical industry. Due to the large volume of generated wastewater, complex composition, and heavy environmental hazard, wastewater recycling is critical f...
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近年来，混合多端直流输电系统快速发展。但是，在混合直流系统中应用的电压源换流器（voltage-source converter, VSC）出口不再需要直流滤波器。此外，考虑到其直流故障电流可被换流器自身有效抑制，直流线路两端也不再需要安装限流电抗器。这意味着线路两端边界缺失，导致应用于常规高压直流输电（line commutated converter based high-voltage direct current, LCC-HVDC）系统和柔性直流（VSC-HVDC）电网的单端量保护均无法适用于混合多端直流输电系统。为此，本文提出了一种适用于混合多端直流输电系统的单端量保护新原理，该方法主要基于暂态信息和主动注入思想实现故障辨识。与应用于LCCHVDC和VSC-HVDC系统的单端量保护相比，所提方法无需依赖线路两端的边界元件，因此更加适用于混合多端直流系统。大量的仿真算例充分验证了所提方法的可行性和优越性。
PWM rectifiers are widely used in the field of new energy power generation. The study of small signal impedance modeling of PWM rectifier is helpful to analyze the stability of new energy grid connected impedance. In ...
PWM rectifiers are widely used in the field of new energy power generation. The study of small signal impedance modeling of PWM rectifier is helpful to analyze the stability of new energy grid connected impedance. In this paper, the small-signal impedance model of the PWM rectifier is first established, and then the impedance model of the PWM rectifier is scanned through MATLAB using the impedance sweep method, and compared with the analytical expressions in this paper, the accuracy of the impedance model of PWM rectifier established in this paper is verified.
In this paper, the non-intrusive monitoring and disaggregation method of industrial load based on Petri net theory is studied. First, the basic concepts of Petri nets are introduced. On the basis of prototype Petri ne...
In this paper, the non-intrusive monitoring and disaggregation method of industrial load based on Petri net theory is studied. First, the basic concepts of Petri nets are introduced. On the basis of prototype Petri nets, time factor is added. Then, the Petri net with time factor is combined with industrial load production process. Considering the production sequence, start-stop time and production time constraints of industrial load, a non-intrusive monitoring and disaggregation model of industrial load is constructed. Finally, according to the actual production process of industrial load, the electricity consumption situation of each production link is calculated, and the detailed analysis results of industrial user's electricity consumption behavior are obtained. The research could provide an important reference for realization of friendly interaction between industrial users and power grid.
During the transitional period of UHV network construction, the power grid's characteristics of 'Strong DC and Weak AC' are prominent. Moreover, the high penetration of renewable energies has made the char...
During the transitional period of UHV network construction, the power grid's characteristics of 'Strong DC and Weak AC' are prominent. Moreover, the high penetration of renewable energies has made the characteristics of power systems profoundly changed facing high operation risks. The security and stability control technologies need to be reviewed considering current development situations and combine the characteristics of the grid to make innovation. This paper analyses the development and status quo of stability control technologies from the security and stability control systems which belong to the second defense line. Moreover, frequency and voltage emergency control devices and out-of-step separation devices which belong to the third defense line, as well as features of the security and stability control devices are investigated. According to the planning and development of the future power grid, the development directions of the security control technology is pointed out.
With the increase of non-linear loads in power grid and the development of power electronics, the growing serious harmonic pollution has put forward higher requirements for the accuracy and real-time performance of th...
With the increase of non-linear loads in power grid and the development of power electronics, the growing serious harmonic pollution has put forward higher requirements for the accuracy and real-time performance of the measurement method. For this problem, this paper proposes a wide-frequency harmonic signal measurement method based on window interpolation FFT and adaptive neural network. After the window function is selected, the frequency of harmonic is estimated by double-spectrum-line interpolation algorithm based on three-term third derivative Nuttall window, and then the smoothed frequencies are input into RLS-Adaline neural network to estimate the amplitude and phase of each harmonic. The simulation results show that the proposed method has higher measurement accuracy and stability under few data conditions and low signal-to-noise ratios than conventional window interpolation algorithms. High accuracy measurement of harmonics with short time window in the range of 0∼2.5kHz is effectively realized.
In view of the reduction of wind turbine operating efficiency caused by wind speed measurement errors, this paper proposes a rated power control strategy for wind turbines for practical applications; in order to solve...
In view of the reduction of wind turbine operating efficiency caused by wind speed measurement errors, this paper proposes a rated power control strategy for wind turbines for practical applications; in order to solve the problem that the pitch PI controller parameters of wind turbines are not easy to calculate and tune in the process of design and optimization, this paper proposes a complete set of methods for parameter tuning of pitch control PI controllers for wind turbines. This paper establishes a Bladed-Matlab co-simulation platform, uses Bladed software to build a complete model of a 2MW wind turbine, and designs a rated power control strategy for wind turbines. After the wind turbine model is linearized at different wind speed points by applying Bladed software, the linearized model for PI parameter tuning is obtained, and then the optimal PI parameters for each wind speed point are set by using particle swarm algorithm. According to the variation law between the PI parameters and the pitch angle obtained before, the PI parameters are adjusted adaptively by variable gain PI control. The simulation results show the superiority of the control strategy and parameter tuning method used in this paper.
The aim of software safety assessment is to evaluate whether the software meets the safety requirements, and this measurement is very important to ensure and confirm the software safety. This paper presents a new soft...
The aim of software safety assessment is to evaluate whether the software meets the safety requirements, and this measurement is very important to ensure and confirm the software safety. This paper presents a new software safety assessment method that is based on the combination of frequency analysis and Analytic Hierarchy Process. First, use frequency analysis method to select some appropriate assessment indicators; then use the Analytic Hierarchy Process to construct the assessment system and assign suitable weight values to indicators at all layers of system; finally rate the software safety. Through the example analysis, it is proved that this method can evaluate software safety very well.
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