Abstract: A DC collection system for a PV power plant contains a large number of feeders. When a fault occurs, the fault current rapidly increases, causing electronic devices to block to protect themselves. This blockage presents a challenge to the protection of the DC collection system because of extremely short data windows. To address this challenge, a protection method based on active control of DC/DC converters is disclosed. The fault current control principle is analyzed and derived so that DC/DC converters can provide an injected low-amplitude and controllable post-fault stable current signal. The disclosed protection method is designed based on identifying the direction of the injected signal. Simulation results indicate that the fault section can be accurately identified and that the disclosed protection method performs efficiently against transition resistance and noise.

Abstract: A general design method for phasor estimation algorithms on different applications is described based on a complex finite impulse response (FIR) band-pass filter. To facilitate the design of the complex band-pass filter for different requirements and reduce the trial and error process, a design framework based on the error mathematical models is described. Using an absolute value inequality theorem, the general error models between the filter gain and the error limitations of all the valuables measured by phasor measurement units (PMUs) are established separately. The filter design criteria obtained by the error models can determine the passband and stopband gain range of complex band-pass filters.

Abstract: A sparse voltage measurement-based fault location determination system and method for an alternating current (AC) distribution network is described. This method can use sparse voltage measurements and Bayesian compressive sensing (BCS) algorithm to reconstruct a sparse current vector. A fault location is then determined based on the reconstructed sparse current vector. The disclosed method provides robust fault location results under a variety of asymmetrical fault scenarios. Fewer intelligent electronic devices (IEDs) allocated in the terminal buses are needed for determining the fault location; therefore, this implementation is relatively cost effective.

Abstract: The wide application of power electronic components in power systems with renewable energy sources has changed the fault characteristics of conventional power systems, resulting in the performance degradation of conventional protections. To solve these problems, a novel principle of pilot protection based on structural similarity and square error criteria is provided. The structural similarity criterion utilizes the difference of fault characteristics between renewable sources and synchronous generators to identify internal faults, and the square error criterion is used to solve abnormal calculation of the conventional similarity based protection. Compared with conventional differential protections, the disclosed protection shows excellent performance in speed and reliability during various faults.

Abstract: A data recovery method framework is described, in which the data is classified as either ambient or disturbance data, and recovered by different methods to achieve good performance efficiently. An approach based on decision tree is described for identifying ambient and disturbance data. Then, an improved cubic spline interpolation based on the priority allocation strategy is described for ambient data loss, which can quickly and accurately recover ambient data. Simultaneously, a disturbance data recovery method based on singular value decomposition is described. It can achieve disturbance data recovery accurately by a single channel of measurement.

Abstract: A detection and location-based active protection method for flexible DC distribution systems with multi-terminal distributed photovoltaic sources is disclosed. The disclosed protection method actively utilizes the coordinated control between local protection and the converters in the DC distribution system. The converter can then be modified to become an injection source with characteristic signal, providing a known fault signal to build a clear protection boundary. The disclosed protection method can distinguish the correct faulted area by calculating the harmonic impedance of the characteristic signals. Compared with existing DC protection techniques, this disclosed method does not require additional injection equipment and modification of the DC distribution system configuration, nor does it need high data sampling frequency. The disclosed technique is also unaffected by measuring noise and cable-distributed capacitance.

Abstract: An improved phasor estimation method for M-class phasor measurement units (PMUs) with a low computational burden is described. The method contains three steps: 1) A phasor measurement filter is designed by selecting parameters of Taylor weighted least square method to prioritize dynamic phasor accuracy and a high level of suppression on high-frequency interferences; 2) A finite impulse response lowpass filter is designed by the equal-ripple method is put forward to suppress low-frequency interferences; and 3) Phasor amplitude is corrected under off-nominal conditions.

Abstract: A general design method for phasor estimation algorithms on different applications is described based on a complex finite impulse response (FIR) band-pass filter. To facilitate the design of the complex band-pass filter for different requirements and reduce the trial and error process, a design framework based on the error mathematical models is described. Using an absolute value inequality theorem, the general error models between the filter gain and the error limitations of all the valuables measured by phasor measurement units (PMUs) are established separately. The filter design criteria obtained by the error models can determine the passband and stopband gain range of complex band-pass filters.

Abstract: A DC collection system for a PV power plant contains a large number of feeders. When a fault occurs, the fault current rapidly increases, causing electronic devices to block to protect themselves. This blockage presents a challenge to the protection of the DC collection system because of extremely short data windows. To address this challenge, a protection method based on active control of DC/DC converters is disclosed. The fault current control principle is analyzed and derived so that DC/DC converters can provide an injected low-amplitude and controllable post-fault stable current signal. The disclosed protection method is designed based on identifying the direction of the injected signal. Simulation results indicate that the fault section can be accurately identified and that the disclosed protection method performs efficiently against transition resistance and noise.

Abstract: A distance protection system and method based on a high-frequency fault component is provided for a renewal energy source (RES) system. The voltage drop caused by a fault has a full frequency of components and this can be extracted by a wavelet transform. A frequency selection principle that renders high-frequency impedance models a stable impedance phase angle is determined. On this basis, internal and external faults with respect to a transmission line are determined by comparing the magnitude of a high-frequency operating voltage with the magnitude of a high-frequency voltage at the fault point. This disclosed protection system and method can eliminate the influence of frequency offset and weak feed of the RES system by using high-frequency signals generated by voltage drops at the fault point, and can also tolerate signal noises and fault resistance.

Abstract: A high-accuracy synchrophasor estimation algorithm for PMU calibration is disclosed. This method can construct a dynamic phasor fitting model. Then, an iterative solution algorithm based on nonlinear fitting can be used to estimate the phasor and frequency, which can include one parameter during the iterations. Moreover, a method is disclosed for calculating the ROCOF based on the least-squares method to improve the ROCOF dynamic accuracy.

Abstract: A high-accuracy synchrophasor estimation algorithm for PMU calibration is disclosed. This method can construct a dynamic phasor fitting model. Then, an iterative solution algorithm based on nonlinear fitting can be used to estimate the phasor and frequency, which can include one parameter during the iterations. Moreover, a method is disclosed for calculating the ROCOF based on the least-squares method to improve the ROCOF dynamic accuracy.

Abstract: A detection and location-based active protection method for flexible DC distribution systems with multi-terminal distributed photovoltaic sources is disclosed. The disclosed protection method actively utilizes the coordinated control between local protection and the converters in the DC distribution system. The converter can then be modified to become an injection source with characteristic signal, providing a known fault signal to build a clear protection boundary. The disclosed protection method can distinguish the correct faulted area by calculating the harmonic impedance of the characteristic signals. Compared with existing DC protection techniques, this disclosed method does not require additional injection equipment and modification of the DC distribution system configuration, nor does it need high data sampling frequency. The disclosed technique is also unaffected by measuring noise and cable-distributed capacitance.

Abstract: An active power distribution network multi-time scale coordinated optimization scheduling method and storage medium are provided. The method includes the following steps: performing long-time scale optimization scheduling of an active power distribution network; performing short-time scale rolling optimization scheduling on the basis of MPC of the active power distribution network according to an optimization result of the long-time scale optimization scheduling of the active power distribution network. By using a model prediction control method, taking the long-time scale optimization scheduling result as a reference, and performing short-time scale rolling correction, the optimization scheduling of the active power distribution network is achieved, thereby reducing unfavorable influences of prediction precision of a distributed power supply and a low-voltage load on the optimization scheduling.

Abstract: A strong cooling direct air-cooled condenser radiating unit and an air-cooled island are provided, comprises a cooling wall, an air supply device and a flow guide device located in the cooling wall. The air supply device comprises a unit air supply channel, an air supply ring, and an air collecting cavity. The air supply ring is located at the lower part of the cooling wall and is an annular body with a cavity. An annular slit outlet is formed in the lower part of the air supply ring. The upper part of the air collecting cavity communicates with the air supply ring. A separating plate is provided in the unit air supply channel and divides the unit air supply channel into upper and lower air flues. The upper air flue communicates with the cavity of the air supply ring. The lower air flue communicates with the air collecting cavity.

Abstract: A combined gas-liquid two-phase energy storage and power generation system includes a compressed gas storage unit, a first gas pipeline, a liquid piston device, a hydraulic energy conversion unit and a first pumped power generation unit. The combined gas-liquid two-phase energy storage and power generation system connects the liquid piston device and a first port group of the hydraulic energy conversion unit and receives/outputs the hydraulic potential from/to the first port group, and connects the first pumped power generation unit with the second port group of the hydraulic energy conversion unit and receives/outputs the hydraulic potential from/to the second port group.

Abstract: A method for quantum key fusion-based virtual power plant security communication includes: identity authentication, performing identity authentication between a client and a server in a virtual power plant based on a communication requirement to acquire a root key; key distribution: generating a key encryption key and a message authentication key based on the acquired root key and performing negotiation on a data encryption key to obtain the data encryption key; and data encryption: encrypting to-be-encrypted data using the data encryption key, and implementing communication of the data. During the identity authentication or the key distribution, negotiation on a quantum key is performed by a quantum key server, and the quantum key obtained by the negotiation is used for implementing the identity authentication or used as the data encryption key. A device for quantum key fusion-based virtual power plant security communication and a computer storage medium are provided.

Abstract: Apparatus and method are provided for remediating trichloroethylene-polluting soils by integrated rotated migration and PRB. The apparatus includes a device of electrokinetic remediation, a PRB and a device of injection of surface active agents. The main components of the device of electrokinetic remediation and PRB include cathode, anode, electrode chamber and PRB. A liquid injection pipe is installed between various electrodes and PRBs. The operation of each device is controlled by each control system. The disclosure integrated rotated migration and PRB for remediating contaminants. Surface active agents is helpful for dispersing TCE from soil. The arrangement of the electrode and the PRB greatly shortens distances and time of pollutant migration, which accelerate the speed of remediation and reduce post-processing procedures. In the process of treatment, the three technical methods promote each other, and have the advantages of good repair effect, short time, no secondary pollution and easy operation.

Abstract: The present invention belongs to the flue gas desulfuration field. Specifically, the present invention relates to a supported solid-phase catalyst for oxidizing the by-product magnesium sulfite in a magnesium desulfuration process, and to preparation method and use thereof. The catalyst uses an activated carbon particle as a support, and cobalt nitrate, manganese nitrate, copper nitrate and ferrous nitrate as catalytically active components. The preparation method is as follows: mixing the pre-treated activated carbon support with the catalytically active components, followed by oscillating, standing under microwave irradiation, filtrating, drying, baking, so as to obtain the supported solid-phase catalyst.

Abstract: A renewable energy-based hybrid bi-directionally interactive DC traction power supply system includes two traction substations. Each substation includes transformers, rectifiers, bidirectional AC-DC converters, a DC bus, a catenary, a steel rail and a section post. A DC bus between two adjacent traction substations is provided with a DC renewable energy system constructed by an electric vehicle charging-discharging system, a distributed generation and more than one low voltage DC microgrid. The DC renewable energy system is connected to the DC bus between two adjacent traction substations through a high voltage DC bus, thus a DC circular microgrid being formed in a power supply section post. The electric vehicle charging-discharging system is formed by more than one bidirectional DC-DC charging-discharging equipments which are intended for in connection with the power batteries of the electric vehicle.