With the evolution of DC distribution networks from traditional radial topologies to more complex multi-branch structures,the number of measurement points supporting synchronous communication remains relatively limite...With the evolution of DC distribution networks from traditional radial topologies to more complex multi-branch structures,the number of measurement points supporting synchronous communication remains relatively limited.This poses challenges for conventional fault distance estimation methods,which are often tailored to simple topologies and are thus difficult to apply to large-scale,multi-node DC networks.To address this,a fault distance estimation method based on sparse measurement of high-frequency electrical quantities is proposed in this paper.First,a preliminary fault line identification model based on compressed sensing is constructed to effectively narrow the fault search range and improve localization efficiency.Then,leveraging the high-frequency impedance characteristics and the voltage-current relationship of electrical quantities,a fault distance estimation approach based on high-frequency measurements from both ends of a line is designed.This enables accurate distance estimation even when the measurement devices are not directly placed at both ends of the faulted line,overcoming the dependence on specific sensor placement inherent in traditional methods.Finally,to further enhance accuracy,an optimization model based on minimizing the high-frequency voltage error at the fault point is introduced to reduce estimation error.Simulation results demonstrate that the proposed method achieves a fault distance estimation error of less than 1%under normal conditions,and maintains good performance even under adverse scenarios.展开更多
With brief statements of the linear electro-optical modulation and magnetooptical modulation, using the method of resultant of optical amplitude vectors and the methed of Jones matrix, formulas for intensity of transm...With brief statements of the linear electro-optical modulation and magnetooptical modulation, using the method of resultant of optical amplitude vectors and the methed of Jones matrix, formulas for intensity of transmitted light through the optical analyzer of various composition of electro-optical effect with magneto-optical effect are derived. The results show that the output beam from the analyzer carries information on current (or magnetic field), voltage (or electric field), active power and apparent power. When the light beam transmitted through the analyzer are transformed into electric signals, three kinds of information are included: the DC term corresponding to an active power, the term with frequency ω(50 Hz) corresponding to current or voltage, and the term with frequency 2ω(100 Hz) corresponding to an apparnt power.So, we can use the electric filter circuit to pick out the DC component for measuring active power; to pick out the component with frequency ω(50 Hz) for measuring current or voltage; and to pick out the component with frequency 2ω(100 Hz) for measuring apparent power. The paper discusses what quantities are measured when the analyzer is set on certain definite values, and ponts out the optimum selection for various measurements.展开更多
Due to the effects of windless and sunless weather, new power systems dominated by renewable energy sources experience power supply shortages, which lead to severe electricity shortages. Because of the insufficient pr...Due to the effects of windless and sunless weather, new power systems dominated by renewable energy sources experience power supply shortages, which lead to severe electricity shortages. Because of the insufficient proportion of controllable thermal power in these systems, this problem must be addressed from the load side. This study proposes an orderly power utilization(OPU) method with load as the primary dispatching object to address the problem of severe electricity shortages. The principles and architecture of the new urban power grid(NUPG) OPU are proposed to complete the load curtailment task and minimize the effects on social production and daily life. A flexible load baseline division method is proposed that considers the effects of factors such as gross domestic product, pollutant emission, and carbon emission to increase the flexibility and applicability of the proposed method. In addition, an NUPG OPU model based on the load baseline is proposed, in which the electric quantity balance aggregator(EQBA) serves as a regular participant in the OPU and eliminates the need for other user involvement within its capacity range. The electric quantity reserve aggregator(EQRA) functions as a supplementary participant in the OPU and primarily performs the remaining tasks of the EQBA. The electric power balance aggregator primarily offsets the power fluctuations of the OPU. Case studies demonstrate the effectiveness and superiority of the proposed model in ensuring the completion of the load curtailment task, enhancing the flexibility and fairness of OPUs, and improving the applicability of the proposed method.展开更多
基金National Natural Science Foundation of China, grant number 52177074.
文摘With the evolution of DC distribution networks from traditional radial topologies to more complex multi-branch structures,the number of measurement points supporting synchronous communication remains relatively limited.This poses challenges for conventional fault distance estimation methods,which are often tailored to simple topologies and are thus difficult to apply to large-scale,multi-node DC networks.To address this,a fault distance estimation method based on sparse measurement of high-frequency electrical quantities is proposed in this paper.First,a preliminary fault line identification model based on compressed sensing is constructed to effectively narrow the fault search range and improve localization efficiency.Then,leveraging the high-frequency impedance characteristics and the voltage-current relationship of electrical quantities,a fault distance estimation approach based on high-frequency measurements from both ends of a line is designed.This enables accurate distance estimation even when the measurement devices are not directly placed at both ends of the faulted line,overcoming the dependence on specific sensor placement inherent in traditional methods.Finally,to further enhance accuracy,an optimization model based on minimizing the high-frequency voltage error at the fault point is introduced to reduce estimation error.Simulation results demonstrate that the proposed method achieves a fault distance estimation error of less than 1%under normal conditions,and maintains good performance even under adverse scenarios.
文摘With brief statements of the linear electro-optical modulation and magnetooptical modulation, using the method of resultant of optical amplitude vectors and the methed of Jones matrix, formulas for intensity of transmitted light through the optical analyzer of various composition of electro-optical effect with magneto-optical effect are derived. The results show that the output beam from the analyzer carries information on current (or magnetic field), voltage (or electric field), active power and apparent power. When the light beam transmitted through the analyzer are transformed into electric signals, three kinds of information are included: the DC term corresponding to an active power, the term with frequency ω(50 Hz) corresponding to current or voltage, and the term with frequency 2ω(100 Hz) corresponding to an apparnt power.So, we can use the electric filter circuit to pick out the DC component for measuring active power; to pick out the component with frequency ω(50 Hz) for measuring current or voltage; and to pick out the component with frequency 2ω(100 Hz) for measuring apparent power. The paper discusses what quantities are measured when the analyzer is set on certain definite values, and ponts out the optimum selection for various measurements.
基金This work was supported by the National Natural Science Foundation of China(No.51877049).
文摘Due to the effects of windless and sunless weather, new power systems dominated by renewable energy sources experience power supply shortages, which lead to severe electricity shortages. Because of the insufficient proportion of controllable thermal power in these systems, this problem must be addressed from the load side. This study proposes an orderly power utilization(OPU) method with load as the primary dispatching object to address the problem of severe electricity shortages. The principles and architecture of the new urban power grid(NUPG) OPU are proposed to complete the load curtailment task and minimize the effects on social production and daily life. A flexible load baseline division method is proposed that considers the effects of factors such as gross domestic product, pollutant emission, and carbon emission to increase the flexibility and applicability of the proposed method. In addition, an NUPG OPU model based on the load baseline is proposed, in which the electric quantity balance aggregator(EQBA) serves as a regular participant in the OPU and eliminates the need for other user involvement within its capacity range. The electric quantity reserve aggregator(EQRA) functions as a supplementary participant in the OPU and primarily performs the remaining tasks of the EQBA. The electric power balance aggregator primarily offsets the power fluctuations of the OPU. Case studies demonstrate the effectiveness and superiority of the proposed model in ensuring the completion of the load curtailment task, enhancing the flexibility and fairness of OPUs, and improving the applicability of the proposed method.
