In order to increase the available power of the electrical energy distribution station and improve the voltage profile of the distribution lines, the use of shunt capacitor banks is indicated. The main results obtaine...In order to increase the available power of the electrical energy distribution station and improve the voltage profile of the distribution lines, the use of shunt capacitor banks is indicated. The main results obtained during this study are: a reduction in subscribed power from 14913.978 kVA to 14010.100 kVA, a reduction in the transformer load rate from 99.4% to 93.4%, a reduction in reactive power called from 5481.729 kVAr to 481.729 kVAr, an increase in the active power transported by the substation from 8505.062 kW to 8962.323 kW, a reduction in the voltage drop from 4.8% to 3.9%, an increase in the power available at the secondary of the transformer station at full load from 13950 kW to 14700 kW and an annual electrical energy saving of 339943.48 kWh of electrical energy, therefore fuel savings and a reduction in CO<sub>2</sub> and SO<sub>2</sub> emissions due to this energy saving will be achieved. The installation of capacitor banks for optimization of reactive energy allowed a reduction in the current called therefore a reduction in the absorbed power: 14153.061 kVA, i.e. a reduction of 903.876 kVA. It is therefore essential that energy players are convinced of the need to install capacitors to reduce or even eliminate their reactive energy bill. This is necessarily accompanied by an investment by Electricité De Guinée by setting up active and reactive energy meters but also by implementing pricing in line with the reduction in the transfer of reactive energy in the network.展开更多
Due to the fact that a high share of renewable energy sources(RESs)are connected to high-voltage direct current(HVDC)sending-end AC power systems,the voltage and frequency regulation capabilities of HVDC sending-end A...Due to the fact that a high share of renewable energy sources(RESs)are connected to high-voltage direct current(HVDC)sending-end AC power systems,the voltage and frequency regulation capabilities of HVDC sending-end AC power systems have diminished.This has resulted in potential system operating problems such as overvoltage and overfrequency,which occur simultaneously when block faults exist in the HVDC link.In this study,a steady-state voltage security-constrained optimal frequency control method for weak HVDC sending-end AC power systems is proposed.The integrated virtual inertia control of RESs is employed for system frequency regulation.Additional dynamic reactive power compensation devices are utilized to control the voltage of all nodes meet voltage security constraints.Then,an optimization model that simultaneously considers the frequency and steady-state voltage security constraints for weak HVDC sending-end AC power systems is established.The optimal control scheme with the minimum total cost of generation tripping and additional dynamic reactive power compensation required is obtained through the optimization solution.Simulations are conducted on a modified IEEE 9-bus test system and practical Qing-Yu line commutated converter based HVDC(LCC-HVDC)sending-end AC power system to verify the effectiveness of the proposed method.展开更多
Distributed photovoltaic(PV)systems play an important role in supplying many recent microgrids.The absence of reactive power support for these small-scale PV plants increases total microgrid losses and voltage-instabi...Distributed photovoltaic(PV)systems play an important role in supplying many recent microgrids.The absence of reactive power support for these small-scale PV plants increases total microgrid losses and voltage-instability threats.Reactive power compensations(RPCs)should be integrated to enhance both microgrid losses and voltage profiles.RPC planning is a non-linear,complicated problem.In this paper,a combined RPC allocation and sizing algorithm is proposed.The RPC-integrating buses are selected using a new adaptive approach of loss sensitivity analysis.In the sizing process,the uncertainties in PV power and load demand are modelled using proper probability density functions.Three simulation techniques for handling uncertainties are compared to define the accurate and fast accurate method as follows:Monte Carlo simulation(MCS),scenario tree construction and reduction method,and point estimation method(PEM).The load flow equations are solved using the forward-backward sweep method.RPCs are optimally sized using the beetle-antenna-based strategy with grey wolf optimization(BGWO)to overcome the local minima problem that appeared in the other pre-proposed methods.Results have been compared using particle swarm optimization and conventional GWO.The proposed model is verified using the IEEE 33 radial bus system.The expected power loss has been reduced by 22% and 31% using compensation of 26% and 44%,respectively.The results obtained prove that the BGWO optimal power flow and PEM to handle the uncertainty can significantly reduce the computation time with sufficient accuracy.Under the study conditions,PEM reduces the computation time to 4 minutes compared with 4 hours for MCS,with only a 3% error compared with MCS as an uncertainty benchmark method.展开更多
文摘In order to increase the available power of the electrical energy distribution station and improve the voltage profile of the distribution lines, the use of shunt capacitor banks is indicated. The main results obtained during this study are: a reduction in subscribed power from 14913.978 kVA to 14010.100 kVA, a reduction in the transformer load rate from 99.4% to 93.4%, a reduction in reactive power called from 5481.729 kVAr to 481.729 kVAr, an increase in the active power transported by the substation from 8505.062 kW to 8962.323 kW, a reduction in the voltage drop from 4.8% to 3.9%, an increase in the power available at the secondary of the transformer station at full load from 13950 kW to 14700 kW and an annual electrical energy saving of 339943.48 kWh of electrical energy, therefore fuel savings and a reduction in CO<sub>2</sub> and SO<sub>2</sub> emissions due to this energy saving will be achieved. The installation of capacitor banks for optimization of reactive energy allowed a reduction in the current called therefore a reduction in the absorbed power: 14153.061 kVA, i.e. a reduction of 903.876 kVA. It is therefore essential that energy players are convinced of the need to install capacitors to reduce or even eliminate their reactive energy bill. This is necessarily accompanied by an investment by Electricité De Guinée by setting up active and reactive energy meters but also by implementing pricing in line with the reduction in the transfer of reactive energy in the network.
基金supported in part by the National Key R&D Program of China(No.2022YFB2402700)the Science and Technology Project of State Grid Corporation of China(No.52272222001J).
文摘Due to the fact that a high share of renewable energy sources(RESs)are connected to high-voltage direct current(HVDC)sending-end AC power systems,the voltage and frequency regulation capabilities of HVDC sending-end AC power systems have diminished.This has resulted in potential system operating problems such as overvoltage and overfrequency,which occur simultaneously when block faults exist in the HVDC link.In this study,a steady-state voltage security-constrained optimal frequency control method for weak HVDC sending-end AC power systems is proposed.The integrated virtual inertia control of RESs is employed for system frequency regulation.Additional dynamic reactive power compensation devices are utilized to control the voltage of all nodes meet voltage security constraints.Then,an optimization model that simultaneously considers the frequency and steady-state voltage security constraints for weak HVDC sending-end AC power systems is established.The optimal control scheme with the minimum total cost of generation tripping and additional dynamic reactive power compensation required is obtained through the optimization solution.Simulations are conducted on a modified IEEE 9-bus test system and practical Qing-Yu line commutated converter based HVDC(LCC-HVDC)sending-end AC power system to verify the effectiveness of the proposed method.
文摘Distributed photovoltaic(PV)systems play an important role in supplying many recent microgrids.The absence of reactive power support for these small-scale PV plants increases total microgrid losses and voltage-instability threats.Reactive power compensations(RPCs)should be integrated to enhance both microgrid losses and voltage profiles.RPC planning is a non-linear,complicated problem.In this paper,a combined RPC allocation and sizing algorithm is proposed.The RPC-integrating buses are selected using a new adaptive approach of loss sensitivity analysis.In the sizing process,the uncertainties in PV power and load demand are modelled using proper probability density functions.Three simulation techniques for handling uncertainties are compared to define the accurate and fast accurate method as follows:Monte Carlo simulation(MCS),scenario tree construction and reduction method,and point estimation method(PEM).The load flow equations are solved using the forward-backward sweep method.RPCs are optimally sized using the beetle-antenna-based strategy with grey wolf optimization(BGWO)to overcome the local minima problem that appeared in the other pre-proposed methods.Results have been compared using particle swarm optimization and conventional GWO.The proposed model is verified using the IEEE 33 radial bus system.The expected power loss has been reduced by 22% and 31% using compensation of 26% and 44%,respectively.The results obtained prove that the BGWO optimal power flow and PEM to handle the uncertainty can significantly reduce the computation time with sufficient accuracy.Under the study conditions,PEM reduces the computation time to 4 minutes compared with 4 hours for MCS,with only a 3% error compared with MCS as an uncertainty benchmark method.
