39results about How to "Does not affect power quality" patented technology

The invention discloses a grid-connected inverter island detection method based on wavelet transform and a neural network. The method is characterized in that the method comprises the following steps: firstly, gathering voltage values of a distributed grid-connected power generation system at a point of common coupling at island state and non-island state and the output current value of an inverter, then performing wavelet transform on the gathered voltage values and the output current value of the inverter and exacting high-frequency component wavelet coefficients to be processed, and finally taking processed signals as input signals of the neural network, and taking corresponding island state and non-island stage as output signals to train the neural network, so as to ensure that the system obtains recognition capability to the island state and the non-island state, and to adopt corresponding island protection measures when the distributed grid-connected power generation system is at the island state. The method can not only overcome the disadvantages of the existing passive island detection method that the detection blind area is large and the detection time is long, but also can solve the problem that the active island detection method affects the power supply quality of the distributed grid-connected power generation system, and rapidly accomplish island detection and island protection.

The invention discloses a method for islanding detection based on harmonic impedance characteristic function pattern recognition and relates to the technical field of electrical property testing methods. The method comprises a step (1) of collecting voltage at a public coupling point and an access current of a distributed type grid-connected power generation system when the distributed type grid-connected power generation system is in an islanding state and a non-islanding state; a step (2) of establishing a harmonic impedance characteristic function phi(k) according to a voltage value and a current value collected in the step (1), and obtaining a characteristic vector space; a step (3) of performing training on a learning sample through pattern recognition, and obtaining the distinguishing capability of the distributed type grid-connected power generation system in the islanding state and the non-islanding state. According to the method, on the premise that electric energy quality is not affected, islanding is accurately detected and islanding protection is performed so as to reduce or even eliminate an islanding detection blind area.

The invention discloses a modular multilevel converter type high-voltage direct-current power transmission (MMC-HVDC) project. After the project is accessed to an alternating-current power grid, a negative sequence direction relay on a power transmission line cannot correctly judge a fault direction and cannot correctly act. In order to solve problems, the invention discloses an MMC-HVDC control strategy assisting in fault direction discrimination. The strategy can assist the negative sequence direction relay to correctly and sensitively identify the fault direction on the basis of basically not influencing safe operation of the MMC, ensures the correct action of the relay, and ensures safety of operation of a power grid.

The invention discloses a multifunctional off-grid type charging pile using methanol as fuel. The multifunctional off-grid type charging pile comprises a whole vehicle control system, a motor control system, an intelligent electric distribution system, an electric vehicle motor, a battery managing system, a fuel supply system, a fuel battery system, an intelligent charging pile, an emergency electric source system, and a power battery system, wherein the whole vehicle control system is connected with the motor control system, the battery managing system, the fuel battery system and the power battery system; the motor control system is connected with the intelligent electric distribution system and the electric vehicle motor; the intelligent electric distribution system is connected with the battery managing system, the fuel battery system, the intelligent charging pile, the emergency electric source system and the power battery system. According to the multifunctional off-grid type charging pile using methanol as fuel disclosed by the invention, alcohol hydrogen fuel which is free from pollution is used for solving the problems of the endurance of an electric vehicle, the charging of the electric vehicle and the electric supply of a communication base station, and the multifunctional off-grid type charging pile has the characteristics of being convenient to operate, short in starting time, long in charging time, low in occupied space, light in weight, low in noise, free from pollution and the like.

The invention relates to an intelligent high-precision voltage stabilizer with self-adaptive wide dynamic power supply. The main loop of the intelligent high-precision voltage stabilizer comprises one compensation transformer, 4 IGBTs (Insulated Gate Bipolar Translators) and an intelligent driving control system; the four IGBTs under the control of input power live wires and chopped waves are connected with a harmonic suppression inductor L1; a first contact (KM1) head and a second contact (KM2) head are connected with the tail end of a primary side of the compensation transformer (T1); and a third contact (KM3) head is connected in parallel with the first end and the tail end of a secondary side of the compensation transformer (T1). As a voltage value is adjusted and compensated by using a chopped wave control technique, wide dynamic power supply and high-precision voltage output are achieved.

The invention discloses a power equal sharing control method of an open-winding dual-inverter photovoltaic power generation system. Aiming at the problem of uneven power distribution between the two inverters caused by the 120-degree decoupling modulation strategy of the common DC bus open-winding dual-inverter photovoltaic power generation system, the present invention proposes a power equalization based on reactive power compensation A control method, the method obtains the reactive current command value of the inverters by adjusting the active power difference between the two inverters, so as to realize the equal power sharing of the two inverters. Compared with the existing method, the present invention does not affect the power quality of grid-connected current while realizing the control target, and the control method is simple and easy for engineering realization.

A micro-grid system with micro-source half-bridge converters in series, including photovoltaic micro-sources, wind micro-sources, energy storage devices, AC / DC rectifier circuits, DC / DC conversion circuits, micro-source half-bridge converters, filtering The inverter, load, transformer, wind power and photovoltaic micro-source are connected in parallel to the DC side of the micro-source half-bridge converter through the AC / DC rectifier circuit or DC / DC conversion circuit, and the energy storage device is connected in parallel to the micro-source DC link. , the output side of each micro-source half-bridge converter is sequentially connected in series, and a three-phase system is built by a double-star combination, in which each phase is composed of two bridge arms, and each bridge arm is composed of N One or n power generating sub-modules are connected in series with an inductor, 2≤N≤50, N=n.

The invention relates to a substation area control method and system of a microgrid operation mode. The substation area control method comprises the following steps of: when a power generation system is subjected to grid-connected power generation according to a first operation mode, if an island operation state appears and a grid-connected power generation mode exits, judging whether the low voltage side of a transformer for a substation corresponding to a second operation mode of the power generation system has voltage, judging which state automatic throw-in equipment of emergency power supply is; if the low voltage side has voltage and is in a commissioning state, receiving correct action formation of the automatic throw-in equipment of emergency power supply and starting the second operation mode; and if the low voltage side does not have voltage or the automatic throw-in equipment of emergency power supply is in an exit state, or the correct action information of the automatic throw-in equipment of emergency power supply is not received within preset time, locking the automatic throw-in equipment of emergency power supply and then starting the microgrid operation mode. According to the substation area control method and system, concentrated judgment and computation are carried out by acquiring real-time operation information of parts in the substation transformer area, which are related to the power generation system, and effective control based on the substation-grid microgrid operation mode is achieved.

The invention relates to a control method and a control device for accessing an energy-storage photovoltaic system into an urban rail traction network, wherein the method comprises the following steps that: 1) whether a photovoltaic battery has energy output or not is judged; if so, the photovoltaic battery has the energy output, a first direct current / direct current (DC / DC) converter and a second DC / DC converter connected with the photovoltaic battery are turned on, the photovoltaic battery starts to work, and then, the operation returns to step 2); if the judgment result shows that the photovoltaic battery does not have the energy output, the photovoltaic battery does not have energy to output, the first DC / DC converter and a second DC / DC converter connected with the photovoltaic battery are turned off, the operation returns to the step 1), whether the photovoltaic battery has the energy output or not is continuously judged, after the operation is repeated for n times, the photovoltaic battery stops working, and the operation returns to the step 2) and other steps. The device comprises the photovoltaic battery, the first DC / DC converter, the second DC / DC converter, a bidirectional DC / DC converter and energy storage equipment. Compared with the prior art, the control method and the control device have the advantages that the energy loss is low, the work efficiency is high, the stability is high, and the like.

The invention discloses a method for remotely and automatically collecting parameters of a ship's power system. Firstly, the current operating parameters of electrical equipment are sampled and held, discretized, encoded, and modulated through a collector to form a high-frequency carrier signal through a coupling circuit of the collector. Coupled into the lighting grid cable, it is transmitted to the concentrator through the lighting cable. The concentrator filters the high-frequency carrier signal from the lighting grid cable, demodulates and decodes it, and obtains the current operating parameters of the electrical equipment. The coupling circuit in the collector of the present invention is conjugate-matched to the lighting cable of the ship, which can realize the maximum transmission power of the carrier signal. The filter circuit in the concentrator matches the lighting cable of the ship without reflection, and the high-frequency carrier signal filtered out is Interferenced by reflected waves, the noise of the ship's lighting grid within the communication frequency band is small, and it has a better communication signal-to-noise ratio.