Abstract: Method for determining parameter of a passive impedance adapter applicable to VSC-HVDC, including: S1. obtaining VSC-HVDC impedance and VSC-HVDC impedance curve X(f) based on VSC-HVDC impedance; S2. estimating upper limit value of the main capacitor in the passive impedance adapter; S3. calculating adapter parameter curve Xadapter(f); S4. determining value of the main capacitor and varying value of the main resistor until min[X(f)?Xadapter(f)] is maximized; determining whether min[X(f)?Xadapter(f)]>k holds; S5. If min[X(f)?Xadapter(f)]>k does not hold, increasing the value of the main capacitor and performing steps S2-S4 until min[X(f)?Xadapter(f)]>k holds when the value of the main capacitor is within the range of the value of the main capacitor, storing the parameters in an available parameter set; S6. reducing the value of the main capacitor, and storing the parameters when min[X(f)?Xadapter(f)]>k holds in the available parameter set; S7.

Abstract: A voltage source type direct-current ice melting apparatus, a flexible interconnection system and a control method are provided. The voltage source type direct-current ice melting apparatus includes a starting unit, a modular multi-level converter and a measurement control unit. The flexible interconnection system includes two voltage source type direct-current ice melting apparatuses having the same circuit structure. The measurement control unit acquires set values, that are input by a user, of relevant parameters and then processes the set values, that are input by the user, of the relevant parameters and measured values, measured in real time by the measurement control unit, of the relevant parameters, thereby determining and sending a control signal, so as to control an operating state of the modular multi-level converter in the apparatus or system.

Abstract: A method and a system for determining a direct current (DC) loop impedance are provided. The method includes: establishing an impedance model for a DC loop of a high-voltage direct current (HVDC) system; scanning parameters in the HVDC system based on the impedance model, to obtain a feasible region of each of the parameters; substituting, for each of the parameters, the parameter in the feasible region into a DC loop impedance equation, to obtain an impedance corresponding to the parameter, the DC loop impedance equation being obtained by transforming the impedance model; and comparing, for each of the parameters, the impedance corresponding to the parameter with a target impedance value, and determining the impedance that meets the target impedance value and the parameter corresponding to the impedance as an optimal impedance and an optimal parameter of the DC loop.

Abstract: The present disclosure provides a parameter design method for a series passive impedance adapter applicable to a VSC-HVDC transmission system, to resolve the technical problem that high-frequency resonance may occur when impedance of a VSC-HVDC transmission system is mismatched with that of a sending-end or receiving-end grid. A parameter design goal of the present disclosure is that reactive power consumed by a series passive impedance adapter is not more than A times rated power of a converter, and a loss of the series passive impedance adapter in a fundamental wave is B times the rated power of the converter. The parameter design method for a series passive impedance adapter applicable to a VSC-HVDC transmission system in the present disclosure can realize a positive impedance characteristic within a concerned frequency band and completely eliminate a risk of harmonic resonance.

Abstract: Disclosed are a voltage source converter based high voltage direct current (VSC-HVDC) high-frequency resonance suppression method, system, and device. The method includes: when an effective value of an actually input alternating current (AC) voltage is reduced from a normal value to meet a preset condition, making the virtual electrical quantity completely equal to the actual electrical quantity, and performing full real-time tracking for the actual electrical quantity to improve dynamic characteristics of a power system at the moment of a fault; and after performing the full tracking for a period of time, if the effective value of the actual AC voltage is less than a preset threshold, performing adaptive tracking until the actual electrical quantity recovers to a stable value. The present disclosure can reduce a risk of high-frequency resonance of a VSC-HVDC, avoid deteriorating dynamic characteristics of the VSC-HVDC, and improve safety of fault ride-through of the VSC-HVDC.

Abstract: The present disclosure provides a parameter design method for a series passive impedance adapter applicable to a VSC-HVDC transmission system, to resolve the technical problem that high-frequency resonance may occur when impedance of a VSC-HVDC transmission system is mismatched with that of a sending-end or receiving-end grid. A parameter design goal of the present disclosure is that reactive power consumed by a series passive impedance adapter is not more than A times rated power of a converter, and a loss of the series passive impedance adapter in a fundamental wave is B times the rated power of the converter. The parameter design method for a series passive impedance adapter applicable to a VSC-HVDC transmission system in the present disclosure can realize a positive impedance characteristic within a concerned frequency band and completely eliminate a risk of harmonic resonance.

Abstract: A method and a device for controlling grid configuration of a flexible direct current electric power transmission system, and a computer-readable storage medium are provided. The active power reference value is modified based on the frequency deviation of the alternating current grid. The reactive power reference value is modified based on the voltage deviation of the alternating current grid. The outputted active power and the outputted reactive power are controlled based on the active power reference value and the reactive power reference value, respectively. The grid voltage is further configured and controlled through power control, so that the system is capable of self-synchronization, frequency regulation and voltage regulation. In addition, the virtual synchronous machine technology is introduced into control of the reactive power, so that the system can provide inertia support for the grid voltage amplitude.

Abstract: Disclosed are a voltage source converter based high voltage direct current (VSC-HVDC) high-frequency resonance suppression method, system, and device. The method includes: when an effective value of an actually input alternating current (AC) voltage is reduced from a normal value to meet a preset condition, making the virtual electrical quantity completely equal to the actual electrical quantity, and performing full real-time tracking for the actual electrical quantity to improve dynamic characteristics of a power system at the moment of a fault; and after performing the full tracking for a period of time, if the effective value of the actual AC voltage is less than a preset threshold, performing adaptive tracking until the actual electrical quantity recovers to a stable value. The present disclosure can reduce a risk of high-frequency resonance of a VSC-HVDC, avoid deteriorating dynamic characteristics of the VSC-HVDC, and improve safety of fault ride-through of the VSC-HVDC.

Abstract: Method for determining parameter of a passive impedance adapter applicable to VSC-HVDC, including: S1. obtaining VSC-HVDC impedance and VSC-HVDC impedance curve X(f) based on VSC-HVDC impedance; S2. estimating upper limit value of the main capacitor in the passive impedance adapter; S3. calculating adapter parameter curve Xadapter(f); S4. determining value of the main capacitor and varying value of the main resistor until min[X(f)?Xadapter(f)] is maximized; determining whether min[X(f)?Xadapter(f)]>k holds; S5. If min[X(f)?Xadapter(f)]>k does not hold, increasing the value of the main capacitor and performing steps S2-S4 until min[X(f)?Xadapter(f)]>k holds when the value of the main capacitor is within the range of the value of the main capacitor, storing the parameters in an available parameter set; S6. reducing the value of the main capacitor, and storing the parameters when min[X(f)?Xadapter(f)]>k holds in the available parameter set; S7.

Abstract: A voltage source converter based DC deicer and its control method are provided. The voltage source converter based DC deicer includes a connecting reactor, a modular multilevel voltage source converter based on a full H-bridge submodule, smoothing reactors, deicing disconnectors, a deicing bus, and a deicing AC line. The AC side of the modular multilevel voltage source converter is connected to an AC side bus through the connecting reactor, an isolation disconnector and a breaker. The DC side of the modular multilevel voltage source converter is connected to the deicing AC line through the smoothing reactors, the deicing disconnectors, and the deicing bus.

Abstract: A modeling method and system for a diode clamped cascaded multi-level converter. All corresponding diodes of each bridge arm are equivalent to an auxiliary diode; all corresponding capacitors of each bridge arm are equivalent to a controlled voltage source; and power modules of each bridge arm are connected in series to be equivalent to an equivalent module, the equivalent module comprising a loss resistor and a composite equivalent model connected to the loss resistor. Since a plurality of components, at the same positions, in each power module of each bridge arm of the diode clamped cascaded multi-level converter are equivalent to a component, the node voltage equation order can be reduced, the simulation efficiency is improved, and the simulation efficiency cannot be reduced with the increase in the number of power modules.

Abstract: A multi-functional automatic switching circuit for direct current ice melting and a switching method thereof are provided. The automatic switching circuit comprises at least one sub-switching circuit. The sub-switching circuit comprises a six-pulse current converter (R) with no saturable reactor, six reactors (L1a, L1b, L1c, L2a, L2b, and L2c), three three-phase knife switches (Sac1, Sac2, and Sac3), and five single-phase knife switches (SV1, SV2, SV3, SV4, and SV5). The sub-switching circuits in series connection or parallel connection, four direct current side switching knife switches (Sdc1, Sdc2, Sdc3, and Sdc4), an isolation knife switch (K), a breaker (QF) and a control and protection system (CP) may form an automatic switching circuit for six-pulse or twelve-pulse direct current ice melting.

Abstract: A voltage source converter based DC deicer and its control method are provided. The voltage source converter based DC deicer includes a connecting reactor, a modular multilevel voltage source converter based on a full H-bridge submodule, smoothing reactors, deicing disconnectors, a deicing bus, and a deicing AC line. The AC side of the modular multilevel voltage source converter is connected to an AC side bus through the connecting reactor, an isolation disconnector and a breaker. The DC side of the modular multilevel voltage source converter is connected to the deicing AC line through the smoothing reactors, the deicing disconnectors, and the deicing bus.

Abstract: A multi-functional automatic switching circuit for direct current ice melting and a switching method thereof are provided. The automatic switching circuit comprises at least one sub-switching circuit. The sub-switching circuit comprises a six-pulse current converter (R) with no saturable reactor, six reactors (L1a, L1b, L1c, L2a, L2b, and L2c), three three-phase knife switches (Sac1, Sac2, and Sac3), and five single-phase knife switches (SV1, SV2, SV3, SV4, and SV5). The sub-switching circuits in series connection or parallel connection, four direct current side switching knife switches (Sdc1, Sdc2, Sdc3, and Sdc4), an isolation knife switch (K), a breaker (QF) and a control and protection system (CP) may form an automatic switching circuit for six-pulse or twelve-pulse direct current ice melting.