CN117559567B

CN117559567B - Control method and device of multiport energy router

Info

Publication number: CN117559567B
Application number: CN202410040572.6A
Authority: CN
Inventors: 任军辉; 侯丹; 刘大鹏; 张树楠
Original assignee: China XD Electric Co Ltd; Xian XD Power Systems Co Ltd
Current assignee: China XD Electric Co Ltd; Xian XD Power Systems Co Ltd
Priority date: 2024-01-11
Filing date: 2024-01-11
Publication date: 2024-04-26
Anticipated expiration: 2044-01-11
Also published as: CN117559567A

Abstract

The invention discloses a control method and a device of a multiport energy router, and relates to the technical field of power systems, wherein the method comprises the following steps: when a direct current fault of a medium-voltage direct current bus occurs, the multi-port energy router determines a fault position through fault detection and positioning, then limits fault current through a locking mode, then disconnects a switch connected with the direct current bus under the condition that the direct current is reduced to be close to zero, and completes isolation of the direct current fault point so as to facilitate the clearing of the fault, if the fault is cleared, a single-ended converter valve can be restarted, reactive power is injected into an alternating current system through each alternating current connection port in a STATCOM mode, the amplitude of the voltage of each alternating current connection port is adjusted through the injection of the reactive power, the voltage of each alternating current connection port is assisted to meet a loop closing condition, loop closing is carried out, and power transmission between the alternating current connection ports is restored. The invention can ensure that the power distribution network system still operates normally when the medium-voltage direct current bus fails.

Description

Control method and device of multiport energy router

Technical Field

The invention relates to the technical field of power systems, in particular to a control method and a device of a multiport energy router.

Background

In recent years, with the increase of the power consumption of the distribution network, the original distribution network cannot meet the demands of users, and needs to meet the demands for the power consumption and the reliability of the power consumption through capacity increase, asynchronous networking, new energy power generation access and other modes. Multiport energy routers are critical devices to solve the above problems. The multi-port energy router can network asynchronous power grids with different voltage levels through a plurality of ports, and meanwhile access of new energy sources such as photovoltaics, energy storage and the like is facilitated through flexible electric energy conversion.

Because the distribution network occasion has higher requirements on the aspects of reliability, efficiency and the like of equipment, when the existing multiport energy router scheme is adopted for the failure of a medium-voltage direct current bus, the power transmission is interrupted, the integral reliability of the system is affected, and the application of the system is not friendly in the distribution network occasion, so that the problem needs to be solved.

Disclosure of Invention

The embodiment of the invention provides a multi-port energy router, which is used for enabling a system to normally operate when a medium-voltage direct-current bus fails, and is arranged in a power distribution network system, wherein the power distribution network system comprises an alternating current system, a direct current system and the multi-port energy router, and the multi-port energy router comprises: the device comprises a plurality of alternating current connection ports, a plurality of direct current connection ports, a plurality of converter transformers, a plurality of converter valves, a plurality of direct current switches, a plurality of alternating current switches and a plurality of direct current transformers;

The first end of each alternating current connection port is connected with an alternating current system, the second end of each alternating current connection port is connected with the first end of a converter transformer, the second end of the converter transformer is connected with the first end of a converter valve, the second end of the converter valve is connected with the first end of a direct current switch through a medium-voltage direct current bus, and the second end of the direct current switch is connected with the second end of any direct current transformer or the second ends of other direct current switches except the current direct current switch through the medium-voltage direct current bus; the first end of the direct current transformer is connected with the second end of the direct current connection port;

The second ends of any two converter transformers are also communicated through a power cable, and an alternating current switch is arranged on the power cable;

The first end of each direct current connection port is connected with the direct current system, and the second end of each direct current connection port is connected with the second end of the direct current transformer.

The embodiment of the invention provides a control method of a multiport energy router, which is used for enabling a system to normally operate when a medium-voltage direct-current bus fails, and comprises the following steps:

when a direct current fault occurs to the medium-voltage direct current bus, determining all converter valves connected at the fault positions of the medium-voltage direct current bus;

Carrying out current limiting treatment on all the converter valves connected at the fault positions of the medium-voltage direct-current buses so as to reduce the current in the medium-voltage direct-current buses;

Monitoring the current in the medium-voltage direct-current bus, wherein the current in the medium-voltage direct-current bus is reduced to a first current threshold value, and the first direct-current switch is disconnected; the first direct current switch comprises all direct current switches connected with all converter valves connected with the fault position of the medium-voltage direct current bus;

Starting at least one first converter valve in all converter valves connected at the fault position of the medium-voltage direct-current bus;

controlling the first converter valve to operate in a static synchronous compensator STATCOM mode;

Controlling a first converter valve in STATCOM mode operation to inject reactive power into a first alternating current system through a first converter transformer until the voltage of each alternating current connection port of the multi-port energy router meets a loop closing condition; the first converter transformer and the first alternating current system are both connected to a first alternating current connection port, and a first end of the first converter valve is connected with a second end of the first converter transformer;

determining an alternating current connection port for ring closing treatment according to ring closing conditions;

and closing a first alternating current switch between the converter transformers connected at the alternating current connection ports needing loop closing treatment so as to enable the multi-port energy router to operate in a loop closing state.

The embodiment of the invention also provides a control device of the multiport energy router, which is used for enabling the system to normally operate when the medium-voltage direct-current bus fails, and the device comprises:

the fault detection module is used for determining all converter valves connected at the fault positions of the medium-voltage direct-current buses;

The fault point clearing module is used for carrying out current limiting treatment on all the converter valves connected at the fault positions of the medium-voltage direct-current buses so as to reduce the current in the medium-voltage direct-current buses; monitoring the current in the medium-voltage direct-current bus, wherein the current in the medium-voltage direct-current bus is reduced to a first current threshold value, and the first direct-current switch is disconnected; the first direct current switch comprises all direct current switches connected with all converter valves connected with the fault position of the medium-voltage direct current bus; starting at least one first converter valve in all converter valves connected at the fault position of the medium-voltage direct-current bus; controlling the first converter valve to operate in a static synchronous compensator STATCOM mode; controlling a first converter valve in STATCOM mode operation to inject reactive power into a first alternating current system through a first converter transformer until the voltage of each alternating current connection port of the multi-port energy router meets a loop closing condition; the first converter transformer and the first alternating current system are both connected to a first alternating current connection port, and a first end of the first converter valve is connected with a second end of the first converter transformer; determining an alternating current connection port for ring closing treatment according to ring closing conditions; and closing a first alternating current switch between the converter transformers connected at the alternating current connection ports needing loop closing treatment so as to enable the multi-port energy router to operate in a loop closing state.

The embodiment of the invention also provides computer equipment, which comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the control method of the multiport energy router is realized when the processor executes the computer program.

The embodiment of the invention also provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program, and the computer program realizes the control method of the multiport energy router when being executed by a processor.

The embodiment of the invention also provides a computer program product, which comprises a computer program, and the computer program realizes the control method of the multiport energy router when being executed by a processor.

The embodiment of the invention provides a multiport energy router, which comprises a plurality of alternating current connection ports, a plurality of direct current connection ports, a plurality of converter transformers, a plurality of converter valves, a plurality of direct current switches, a plurality of alternating current switches and a plurality of direct current transformers; the first end of each alternating current connection port is connected with an alternating current system, the second end of each alternating current connection port is connected with the first end of a converter transformer, the second end of the converter transformer is connected with the first end of a converter valve, the second end of the converter valve is connected with the first end of a direct current switch through a medium-voltage direct current bus, and the second end of the direct current switch is connected with the second end of any direct current transformer or the second ends of other direct current switches except the current direct current switch through the medium-voltage direct current bus; the first end of the direct current transformer is connected with the second end of the direct current connection port; the second ends of any two converter transformers are also communicated through a power cable, and an alternating current switch is arranged on the power cable; the first end of each direct current connection port is connected with the direct current system, and the second end of each direct current connection port is connected with the second end of the direct current transformer. The multi-port energy router in the embodiment of the invention can solve the problem of active power transmission interruption caused by the failure of the medium-voltage direct-current bus, and can temporarily provide active power exchange among all ports, so that the power distribution network system still operates normally when the failure of the medium-voltage direct-current bus occurs.

According to the control method of the multiport energy router, when a direct current fault of a medium-voltage direct current bus occurs, all converter valves connected at the fault position of the medium-voltage direct current bus are determined; carrying out current limiting treatment on all the converter valves connected at the fault positions of the medium-voltage direct-current buses so as to reduce the current in the medium-voltage direct-current buses; monitoring the current in the medium-voltage direct-current bus, wherein the current in the medium-voltage direct-current bus is reduced to a first current threshold value, and the first direct-current switch is disconnected; the first direct current switch comprises all direct current switches connected with all converter valves connected with the fault position of the medium-voltage direct current bus; starting at least one first converter valve in all converter valves connected at the fault position of the medium-voltage direct-current bus; controlling the first converter valve to operate in a static synchronous compensator STATCOM mode; controlling a first converter valve in STATCOM mode operation to inject reactive power into a first alternating current system through a first converter transformer until the voltage of each alternating current connection port of the multi-port energy router meets a loop closing condition; the first converter transformer and the first alternating current system are both connected to a first alternating current connection port, and a first end of the first converter valve is connected with a second end of the first converter transformer; determining an alternating current connection port for ring closing treatment according to ring closing conditions; and closing a first alternating current switch between the converter transformers connected at the alternating current connection ports needing loop closing treatment so as to enable the multi-port energy router to operate in a loop closing state. In the embodiment of the invention, when a direct current fault of a medium-voltage direct current bus occurs, the multi-port energy router firstly determines the fault position through fault detection and positioning, then limits fault current through a locking mode, and then can disconnect a switch connected with the direct current bus under the condition that the direct current is reduced to be close to zero, so that the isolation of the direct current fault point is finished, the fault is convenient and clear, if the fault is cleared, a single-ended converter valve can be restarted, and reactive power is injected into an alternating current system through each alternating current connection port in a STATCOM mode. The amplitude of the voltage of each alternating current connection port is adjusted through reactive power injection, the voltage of each alternating current connection port is assisted to meet the loop closing condition, loop closing is carried out, and power transmission between the alternating current connection ports is restored. The embodiment of the invention ensures that the power distribution network system still operates normally when the medium-voltage direct current bus fails, and solves the problem of active power transmission interruption caused by the medium-voltage direct current bus failure.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. In the drawings:

FIG. 1 is a schematic diagram of a multiport energy router in an embodiment of the present invention;

Fig. 2 is a schematic flow chart of an auxiliary loop closing flow under the condition of a fault of a medium-voltage direct-current bus in an embodiment of the invention;

FIG. 3 is a schematic diagram of a flow of power supplied by a single-ended AC switch in an island mode of operation according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a flow of power supplied by a single-ended AC switch during maintenance in an embodiment of the invention;

FIG. 5 is a schematic diagram of a method for calculating reactive current according to an embodiment of the present invention;

fig. 6 is a schematic diagram of a control device of a multiport energy router according to an embodiment of the present invention.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention will be described in further detail with reference to the accompanying drawings. The exemplary embodiments of the present invention and their descriptions herein are for the purpose of explaining the present invention, but are not to be construed as limiting the invention.

In the description of the present invention, the terms "first," "second," "third," and the like are not used in a special sense, but are used for convenience of description, and identify the same or similar technical content, features, and effects of the present invention, for example, the first ac connection port is only used for describing one ac connection port, and the first end is only used for distinguishing from other ends.

The technical scheme of the application obtains, stores, uses, processes and the like the data, which all meet the relevant regulations of national laws and regulations.

The applicant finds that when the existing multiport energy router scheme fails in a medium-voltage direct-current bus, power transmission is interrupted, the reliability of the whole system is affected, and the scheme is not friendly to be applied to power distribution network occasions. To this end, applicant proposes a multiport energy router.

In the embodiment of the invention, the multiport energy router is arranged in a power distribution network system, the power distribution network system comprises an alternating current system, a direct current system and the multiport energy router, and the multiport energy router at least comprises: the device comprises a plurality of alternating current connection ports, a plurality of direct current connection ports, a plurality of converter transformers, a plurality of converter valves, a plurality of direct current switches, a plurality of alternating current switches and a plurality of direct current transformers;

Referring to fig. 1, fig. 1 is a schematic topology diagram of a multiport energy router according to an embodiment of the present invention, in fig. 1, three ac connection ports+one dc connection port are taken as an example, the three ac connection ports are PCCAC, PCCAC, PCCAC, respectively, the dc connection port PCCDC4, the ac switch qs_a, the dc switch QS, and the converter valve includes an upper bridge arm and a lower bridge arm, the ac ends of the upper bridge arm and the lower bridge arm (i.e., the first ends of the converter valves) are connected with the second ends of the converter transformer, and the dc ends of the upper bridge arm and the lower bridge arm (i.e., the second ends of the converter valves) are connected with other dc connection ports or the dc ends of other converter valves. The exemplary four-port energy router shown in fig. 1 is illustrated as an example in fig. 1 as being connected via an ac switch qs_a on the outer ring and via a medium voltage dc bus on the inner ring. The position of the medium-voltage direct current bus is very important, and once the medium-voltage direct current bus fails, such as a common short circuit fault, four ports of the whole system cannot work normally, and active power transmission among the ports is interrupted. In general, the position of the medium-voltage bus is designed to reduce the probability of failure as much as possible according to the actual situation of the system, but the failure cannot be completely avoided. There is therefore a need for an improvement to the above-described problems to increase the reliability of the system in the event of a system failure and to resume active power transmission of the system as soon as possible.

In one embodiment, the third end of each ac connection port is provided with means for measuring voltage.

That is, the voltage may be measured or monitored at the ac connection port, while the current may also be measured or monitored. The device for testing the current is strung in the circuit of the alternating current connection port.

Based on the multiport energy router in the embodiment of the invention, the inventor provides a control method of the multiport energy router, which is applied to the multiport energy router. Fig. 2 is a flow chart of an auxiliary loop closing flow under the condition of a fault of a medium voltage dc bus in an embodiment of the present invention, as shown in fig. 2, where the medium voltage dc bus has a dc fault, and the method includes:

Step 201, determining all converter valves connected at the fault positions of the medium-voltage direct-current buses;

202, performing current limiting treatment on all converter valves connected to the fault position of the medium-voltage direct-current bus so as to reduce the current in the medium-voltage direct-current bus;

Step 203, monitoring current in a medium-voltage direct-current bus, wherein the current in the medium-voltage direct-current bus is reduced to a first current threshold value, and the first direct-current switch is disconnected; the first direct current switch comprises all direct current switches connected with all converter valves connected with the fault position of the medium-voltage direct current bus;

Step 204, starting at least one first converter valve in all converter valves connected at the fault position of the medium-voltage direct-current bus;

Step 205, controlling the first converter valve to operate in a static synchronous compensator (STATCOM) mode;

step 206, controlling a first converter valve in STATCOM mode operation to inject reactive power into a first alternating current connection port through a first converter transformer until the voltage of each alternating current connection port of the multi-port energy router meets a loop closing condition; the first converter transformer and the first alternating current system are both connected to a first alternating current connection port, and a first end of the first converter valve is connected with a second end of the first converter transformer;

Step 207, determining an alternating current connection port for ring closing according to the ring closing condition;

step 208, closing a first ac switch between the converter transformers connected at the ac connection ports where the loop closing process is required, so that the multiport energy router operates in a loop closing state.

As can be seen from the flow shown in fig. 2, in the embodiment of the present invention, an ac switch is configured on the valve side of the converter transformer of any two ac connection ports, and in the case that a medium voltage dc bus fails, the multiport energy router first determines the fault location through fault detection and positioning, then limits the fault current through blocking or traversing, and then can disconnect the switch connected to the dc bus under the condition that the dc current drops to be close to zero, so as to complete the clearing of the dc fault point. After the fault is cleared, the single-ended converter valve can be restarted, and the converter valve running in the STATCOM mode injects reactive power into the alternating current connection port corresponding to the fault position. And (3) adjusting the amplitude of the voltage of each alternating current connection port by injecting reactive power, assisting the voltage of the ports to meet the loop closing condition, closing the loops, and recovering the power transmission between the ports.

When the method is implemented, a direct current fault occurs in the medium-voltage direct current bus, firstly, the fault is searched and positioned, if the fault is a permanent fault, the converter valve is locked, the corresponding direct current switch is opened, and fault isolation is completed. And starting the converter valve, controlling the converter valve to operate in a STATCOM mode, calculating a reactive current value required by meeting the loop closing condition, injecting reactive power into an alternating current connection port corresponding to the fault position until the loop closing condition is met, closing an alternating current switch between converter transformers connected at the alternating current connection port which is required to be subjected to loop closing treatment, enabling the multi-port energy router to enter the loop closing state, adjusting the reactive power according to the control requirement of an energy management system, and if the reactive power injection is not required, exiting the operation.

In one embodiment, after the multiport energy router operates in a closed state, it may further comprise:

when the direct current fault of the medium-voltage direct current bus is recovered, the direct current voltage of all the converter valves on the two sides of the first direct current switch is regulated, and the first direct current switch is closed;

Receiving active power transmitted by a first alternating current system line until the alternating current power at a first alternating current connection port is reduced to a first threshold value; the first threshold is used for judging whether to disconnect the alternating current connection switch according to the alternating current power;

the first ac switch is turned off.

In this example, after the fault recovery of the medium voltage dc bus, the active power flow is not controlled flexibly by the ac connection mode, and the control energy is very limited, so that the energy router needs to be put into again. If the converter valve is in the exit state before, recharging and starting are needed, if the converter valve is operated in the STATCOM mode before, direct-current voltage needs to be adjusted, a direct-current switch is closed, and primary circuit connection of the converter valve is restored. The active power transmitted through the alternating current line is gradually transferred to the multiport energy router, and when the alternating current is close to zero, the alternating current switch is opened, and the normal operation state of the energy router is restored.

Specifically, the direct current fault of the medium-voltage direct current bus is recovered, the previously withdrawn converter valve is restarted, the direct current voltage is regulated by the online converter valve, and the direct current switch is closed, so that the recovery of the direct current system is completed. The active power transmitted through the AC line is transferred to the multiport energy router, when the AC power at the AC connection port is reduced to be close to zero, the AC switch is disconnected, and the normal operation is restored.

Fig. 3 is a schematic flow chart of power supply by a single-ended ac switch in an island operation mode according to an embodiment of the present invention, as shown in fig. 3, when a second ac connection port is operated in the island mode, the second ac connection port is any ac connection port, and a control method of a multiport energy router according to an embodiment of the present invention includes:

Step 301, determining a plurality of alternating current connection ports adjacent to the second alternating current connection port;

Step 302, sorting a plurality of alternating current connection ports adjacent to the second alternating current connection port from high to low according to the idle capacity to form a port sequence;

Step 303, adjusting the ac voltage of the second ac connection port until the ac voltage of the second ac connection port is consistent with the ac voltage of the third ac connection port sequenced first in the port sequence;

Step 304, closing an alternating current switch between the second converter transformer and the third converter transformer, and supplying power to the second alternating current connection port by using a third alternating current system; the second alternating current system and the second converter transformer are connected with the second alternating current connecting port, and the third alternating current system and the third converter transformer are connected with the third alternating current connecting port;

Step 305, controlling the second converter valve to gradually reduce power and quit operation; the second converter valve is connected to the second converter transformer.

In this example, when one of the ac connection ports operates in the island mode, by calculation of the energy management system (the energy management system is generally used for measurement and management of energy exchange among the multiple ports in the multiport energy router), one ac connection port may be selected for ac direct power supply, and one ac connection port with a larger idle capacity may be generally selected for power supply to the island load. After the AC connection port is selected, the AC voltage of the island AC connection port can be adjusted to be consistent with the voltage of the AC connection port for power supply, then a corresponding AC switch is closed, the active power and reactive power of the island AC connection port are reduced, and the island load is supplied with power through the AC switch. The converter valve at the island alternating current connection port can gradually reduce power and quit running, so that the power supply efficiency can be improved and the loss can be reduced by directly supplying power through alternating current.

Further, after the third ac system is used to power the second ac connection port, the method may further include:

if the load of the second alternating current system increases beyond the power supply capacity of the third alternating current system, determining a fourth alternating current connection port for sequencing the second in the port sequence;

powering the second ac connection port using a fourth ac system; the fourth alternating current system and the fourth converter transformer are connected to the fourth alternating current connection port.

In this case, when the power of one of the ac systems is insufficient to provide the island load, the power requirement can be satisfied by adjusting the transmission power of the third terminal. For example, when the ac system 2 fails and needs to trip, the original load of the ac system 2 operates in an island mode, in order to reduce the loss, a corresponding ac switch may be turned on according to the flow shown in fig. 3, according to the load conditions of the ac system 1 and the ac system 3 connected by adjacent ac connection ports, the load of the ac system 2 is supplied by selecting the end with larger idle capacity, assuming that the idle capacity of the ac system 1 is larger, the output voltage of the ac side (the first end) of the converter valve at the end of the ac system 2 may follow the ac system 1, after the voltages at the two ac connection ports are consistent, the ac switch qs_a between the ac system 1 and the ac system 2 may be turned on, the load of the ac system 2 may be directly supplied by the ac system 1, and the converter valve at the end of the ac system 2 may be exited. How the load of the ac system 2 increases beyond the power supply capability of the ac system 1, the power supply requirement can be satisfied by adjusting the power transmission of the ac system 3 and the dc system 4.

Fig. 4 is a schematic flow chart of power supply through a single-ended ac switch during maintenance in an embodiment of the present invention, as shown in fig. 4, when a fifth ac connection port is maintained, the fifth ac connection port is any ac connection port, and the method includes:

step 401, determining a sixth alternating current connection port from a plurality of alternating current connection ports adjacent to the fifth alternating current connection port, and supplying power to the fifth alternating current connection port by using a sixth alternating current system; the sixth alternating current system and the sixth converter transformer are connected with a sixth alternating current connection port;

step 402, reducing the active power of the fifth alternating current connection port until the active power is zero;

Step 403, turning off a fifth direct current switch; the fifth direct current switch is connected with the second end of the fifth converter valve, and the fifth converter valve is connected with a fifth alternating current connection port through a fifth converter transformer;

step 404, controlling the fifth converter valve to operate in a STATCOM mode;

Step 405, controlling a fifth converter valve in a STATCOM mode to inject reactive power into a fifth ac connection port until voltages of the fifth ac connection port and a sixth ac connection port of the multiport energy router meet a loop closing condition; the fifth alternating current system and the fifth converter transformer are connected with a fifth alternating current connection port;

Step 406, determining an alternating current connection port needing ring closing processing;

step 407, closing a second ac switch between the converter transformers connected at the ac connection ports where the loop closing process is required, so that the multi-port energy router operates in a loop closing state;

step 408, reducing reactive power of the fifth ac connection port until it is zero;

and 409, controlling the fifth converter valve to stop, and disconnecting the fifth alternating current connection port from the fifth alternating current system.

In this example, when a certain ac connection port is overhauled (referred to as an overhauling end), the ac connection port for power supply is first determined by the energy management system, and referring to the method in fig. 3, an ac connection port with a larger idle capacity is selected as well. And reducing the active power of the overhaul end until the active power is zero, opening a direct current switch corresponding to the overhaul end converter valve, and operating the converter valve to be overhauled in a STATCOM mode. And calculating reactive power required by meeting the loop closing condition, injecting reactive power adjustment voltage into the inspection and maintenance end, and closing the alternating current switch QS_A when the valve side voltage of the converter transformer at the inspection and maintenance end is the same as or close to the valve side voltage of the alternating current connection port for power supply, namely the loop closing condition is met. And reducing the reactive power of the overhaul end until the reactive power is zero, stopping the overhaul end, and disconnecting the AC connection system connected with the overhaul end. Entering into maintenance state.

Further, controlling the fifth converter valve to stop, and after disconnecting the fifth ac connection port from the fifth ac system, the method may further include:

After the maintenance of the fifth alternating current connection port is finished, a fifth converter valve is started, the direct current voltage is adjusted, and after the switching-on condition of the direct current switch is met, the fifth direct current switch is closed;

receiving active power transmitted by a fifth alternating current system line until the alternating current power of a fifth alternating current connection port is reduced to a first threshold value;

the second ac switch is turned off.

In the embodiment, after the maintenance is completed, the withdrawn converter valve is restarted, the direct-current voltage is adjusted, and after the closing condition of the direct-current switch is met, the direct-current switch is closed, so that the recovery of the direct-current system is completed. Active power transmitted through the ac line is transferred to the multiport energy router. And when the alternating current power is close to zero, the alternating current switch is turned on, and the power distribution network system resumes normal operation.

In the embodiment of the present invention, the satisfaction of the general judgment condition of ring closure may include the following:

1. the phase of the ring closing point should be consistent. If the phase change is possibly caused after the first ring closing or maintenance, the phase of the two sides of the ring closing point must be proved to be consistent through measurement.

2. If the transformer belongs to the electromagnetic ring network, the difference between the transformer wiring groups in the ring network is zero; under special conditions, the relay protection is verified through calculation, so that misoperation and overload of related loop equipment are avoided, and the loop closing operation is allowed when the wiring difference of the transformer is 30 degrees.

3. The overload of each element in the ring network can not be caused after the ring is closed.

4. The respective bus voltages should not exceed a prescribed value.

5. The relay protection and safety automatic device is suitable for the operation mode of the ring network.

6. The stability of the power grid meets the specified requirements.

In the whole design, the design of the transformer wiring form is carried out by comprehensively considering the voltage regulation requirement during the loop closing, so that the phases of the valve sides at the two ends are as consistent as possible, and the system can meet the loop closing requirement as much as possible.

Fig. 5 is a schematic diagram of a method for calculating reactive current in an embodiment of the present invention, and as shown in fig. 5, the reactive power injection may include:

The reactive current value to be injected is determined as follows:

firstly, primary side voltages of a converter transformer connected with two alternating current connection ports needing loop closing are obtained, specifically, the primary side voltages of the converter transformer with the two ports needing loop closing are obtained through a detection device, and the primary side voltages can specifically comprise amplitude values and phases of the voltages, such as V1 and V2 shown in fig. 5, and V1 can be expressed as V1 x cos theta based on V2, wherein theta represents an included angle between V1 and V2. The Δv1q is the maximum voltage drop range of the reactive current of the converter transformer on the equivalent inductance of the transformer, which is generated by the ac connection port (abbreviated as V1 end) at the converter transformer with the primary voltage V1, and Δv1q is the voltage drop of the reactive current actually required to be injected on the equivalent inductance of the converter transformer. The Δv2q is the maximum voltage drop range of the reactive current of the converter transformer on the equivalent inductance of the transformer, which is generated by the ac connection port (abbreviated as V2 end) at the converter transformer with the primary voltage V2, and Δv2q is the voltage drop of the reactive current actually required to be injected on the equivalent inductance of the converter transformer. Delta V is the secondary voltage difference of the converter transformer at the two AC connection ports when the ring is actually closed.

When the voltage difference between the two ac connection ports of the closed loop is required to be relatively large, the injection according to the maximum reactive current may exist, but the voltage difference still cannot be fully compensated, and a certain voltage difference still exists when the loop is closed, as shown in fig. 5. Wherein the reactive current injection is calculated in such a way that the magnitude of av is minimized. The specific calculation method comprises the following steps:

When (when) Where θ1=arctan (Δv1q×v1), Δv1q=iqmax×w×l1, iqmax is the maximum value of reactive current, w is the angular frequency, L1 is the equivalent inductance of the converter transformer with primary voltage V1, and the reactive current value is determined according to the following formula:

Iq1=Iqmax；

Iq1 is a reactive current value to be injected at the V1 end, iq2 is a reactive current value to be injected at the V2 end, wherein L2 is an equivalent inductance of the converter transformer with the primary side voltage of V2;

When the voltage difference between the two ports is not large, i.e. The reactive current value is determined as follows:

where Iq1 is a reactive current value to be injected at the V1 end, iq2 is a reactive current value to be injected at the V2 end, θ2=θ—θ1.

In summary, the embodiment of the invention has the following beneficial effects:

1. The problem of active power transmission interruption caused by the faults of the medium-voltage direct-current bus can be solved, and active power exchange among ports can be provided temporarily.

2. The power supply efficiency of island power supply is improved, and the loss is reduced.

3. When the system is overhauled at a single end, power supply can be realized through a connecting switch, and transmission power interruption is avoided.

The embodiment of the invention also provides a control device of the multiport energy router, as described in the following embodiment. Because the principle of the device for solving the problem is similar to that of the multiport energy router, the implementation of the device can be referred to the implementation of the multiport energy router control method, and the repetition is omitted.

Fig. 6 is a schematic diagram of a control device of a multiport energy router according to an embodiment of the present invention, as shown in fig. 6, applied to the multiport energy router, in which a dc fault occurs in a medium voltage dc bus, the device includes:

The fault detection module 601 is used for determining all converter valves connected at the fault position of the medium-voltage direct-current bus;

The fault point clearing module 602 is configured to perform current limiting treatment on all the converter valves connected at the fault location of the medium-voltage direct-current bus, so that current in the medium-voltage direct-current bus is reduced; monitoring the current in the medium-voltage direct-current bus, wherein the current in the medium-voltage direct-current bus is reduced to a first current threshold value, and the first direct-current switch is disconnected; the first direct current switch comprises all direct current switches connected with all converter valves connected with the fault position of the medium-voltage direct current bus; starting at least one first converter valve in all converter valves connected at the fault position of the medium-voltage direct-current bus; controlling the first converter valve to operate in a static synchronous compensator STATCOM mode; controlling a first converter valve in STATCOM mode operation to inject reactive power into a first alternating current system through a first converter transformer until the voltage of each alternating current connection port of the multi-port energy router meets a loop closing condition; the first converter transformer and the first alternating current system are both connected to a first alternating current connection port, and a first end of the first converter valve is connected with a second end of the first converter transformer; determining an alternating current connection port for ring closing treatment according to ring closing conditions; and closing a first alternating current switch between the converter transformers connected at the alternating current connection ports needing loop closing treatment so as to enable the multi-port energy router to operate in a loop closing state.

In one embodiment, the apparatus further comprises:

The first repair module is used for recovering the direct current faults of the medium-voltage direct current bus after the multi-port energy router operates in a closed state, adjusting the direct current voltages of all the converter valves at the two sides of the first direct current switch and closing the first direct current switch;

the first ac switch is turned off.

In one embodiment, the apparatus further comprises:

the island mode first processing module is used for determining a plurality of alternating current connection ports adjacent to a second alternating current connection port when the second alternating current connection port operates in an island mode, wherein the second alternating current connection port is any alternating current connection port;

Sequencing a plurality of alternating current connection ports adjacent to a second alternating current connection port from high to low according to the idle capacity to form a port sequence;

adjusting the alternating voltage of the second alternating current connection port until the alternating voltage of the second alternating current connection port is consistent with the alternating voltage of a third alternating current connection port sequenced first in the port sequence;

Closing an alternating current switch between the second converter transformer and the third converter transformer, and supplying power to the second alternating current connection port by using a third alternating current system; the second alternating current system and the second converter transformer are connected with the second alternating current connecting port, and the third alternating current system and the third converter transformer are connected with the third alternating current connecting port;

Controlling the second converter valve to gradually reduce power and quit operation; the second converter valve is connected to the second converter transformer.

In one embodiment, the apparatus further comprises:

The island mode second processing module is used for determining a fourth alternating current connection port for sequencing a second in the port sequence if the load of the second alternating current system increases beyond the power supply capacity of the third alternating current system after the island mode first processing module supplies power to the second alternating current connection port by using the third alternating current system;

In one embodiment, the apparatus comprises:

The single-end overhauling first processing module is used for overhauling a fifth alternating-current connecting port, wherein the fifth alternating-current connecting port is any alternating-current connecting port, a sixth alternating-current connecting port is determined from a plurality of alternating-current connecting ports adjacent to the fifth alternating-current connecting port, and a sixth alternating-current system is used for supplying power to the fifth alternating-current connecting port; the sixth alternating current system and the sixth converter transformer are connected with a sixth alternating current connection port;

reducing the active power of the fifth alternating current connection port until the active power is zero;

opening the fifth direct current switch; the fifth direct current switch is connected with the second end of the fifth converter valve, and the fifth converter valve is connected with a fifth alternating current connection port through a fifth converter transformer;

controlling the fifth converter valve to operate in a STATCOM mode;

Controlling a fifth converter valve in a STATCOM mode to inject reactive power into a fifth alternating current connection port until the voltages of the fifth alternating current connection port and a sixth alternating current connection port of the multi-port energy router meet a loop closing condition; the fifth alternating current system and the fifth converter transformer are connected with a fifth alternating current connection port;

determining an alternating current connection port needing ring closing treatment;

closing a second alternating current switch between the converter transformers connected at the alternating current connection ports needing ring closing treatment so as to enable the multi-port energy router to operate in a ring closing state;

Reducing reactive power of the fifth alternating current connection port until the reactive power is zero;

and controlling the fifth converter valve to stop, and disconnecting the fifth alternating current connection port from the fifth alternating current system.

In one embodiment, the apparatus further comprises:

The single-end overhauling second processing module is used for starting a fifth converter valve after overhauling of a fifth alternating-current connecting port is finished, adjusting direct-current voltage, and closing a fifth direct-current switch after the direct-current switch closing condition is met;

the second ac switch is turned off.

In one embodiment, the device, when injecting reactive power, comprises:

The reactive current value to be injected is determined as follows:

acquiring primary side voltages of a converter transformer connected with two alternating current connection ports needing ring closing;

When (when) Wherein V1 and V2 are primary side voltages of the converter transformer connected by two ac connection ports needing to be looped respectively, θ1=arctan (Δv1q×v1), Δv1q=iqmax×w×l1, iqmax is a reactive current maximum value, w is an angular frequency, L1 is a converter transformer equivalent inductance with primary side voltage V1, and the reactive current value is determined according to the following formula:

Iq1=Iqmax；

/>

iq1 is a reactive current value to be injected into an alternating current system connected with an alternating current connection port at a converter transformer with primary side voltage V1, iq2 is a reactive current value to be injected into an alternating current system connected with an alternating current connection port at a converter transformer with primary side voltage V2, wherein θ represents an included angle between V1 and V2, and L2 is an equivalent inductance of the converter transformer with primary side voltage V2;

When (when) The reactive current value is determined as follows:

In the formula, iq1 is a reactive current value to be injected into an alternating current system connected with an alternating current connection port at a converter transformer with primary side voltage V1, iq2 is a reactive current value to be injected into an alternating current system connected with an alternating current connection port at a converter transformer with primary side voltage V2, and θ2=θ - θ1.

It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims

1. The control method of the multi-port energy router is characterized by being applied to the multi-port energy router, wherein the multi-port energy router is arranged in a power distribution network system, the power distribution network system comprises an alternating current system, a direct current system and the multi-port energy router, and the multi-port energy router comprises: the device comprises a plurality of alternating current connection ports, a plurality of direct current connection ports, a plurality of converter transformers, a plurality of converter valves, a plurality of direct current switches, a plurality of alternating current switches and a plurality of direct current transformers;

The first end of each direct current connection port is connected with a direct current system, and the second end of each direct current connection port is connected with the second end of the direct current transformer;

When a direct current fault occurs in the medium-voltage direct current bus, the method comprises the following steps:

determining all converter valves connected at the fault positions of the medium-voltage direct-current buses;

controlling a first converter valve in STATCOM mode operation to inject reactive power into a first alternating current connection port through a first converter transformer until the voltage of each alternating current connection port of the multi-port energy router meets a loop closing condition; the first converter transformer and the first alternating current system are connected to a first alternating current connection port, and a first end of the first converter valve is connected with a second end of the first converter transformer;

2. The method of claim 1, further comprising, after the multiport energy router operates in a closed state:

When the direct current fault of the medium-voltage direct current bus is recovered, the direct current voltages of all the converter valves at the two sides of the first direct current switch are adjusted, and the first direct current switch is closed;

the first ac switch is turned off.

3. The method of claim 1, wherein when the second ac connection port is operating in island mode, the second ac connection port is any ac connection port, the method comprising:

Determining a plurality of ac connection ports adjacent to the second ac connection port;

4. The method of claim 3, further comprising, after powering the second ac connection port with the third ac system:

5. The method of claim 1, wherein when the fifth ac connection port is serviced, the fifth ac connection port is any ac connection port, the method comprising:

Determining a sixth ac connection port from a plurality of ac connection ports adjacent to the fifth ac connection port, powering the fifth ac connection port with the sixth ac system; the sixth alternating current system and the sixth converter transformer are connected with a sixth alternating current connection port;

controlling the fifth converter valve to operate in a STATCOM mode;

6. The method of claim 5, wherein controlling the fifth converter valve to shut down, after disconnecting the fifth ac connection port from the fifth ac system, further comprises:

the second ac switch is turned off.

7. The method of claim 1 or 5, wherein injecting reactive power comprises:

The reactive current value to be injected is determined as follows:

Iq1=Iqmax；

；

When (when) The reactive current value is determined as follows:

；

8. A control device of a multi-port energy router, which is applied to a multi-port energy router, wherein the multi-port energy router is disposed in a power distribution network system, the power distribution network system comprises an ac system, a dc system and a multi-port energy router, and the multi-port energy router comprises: the device comprises a plurality of alternating current connection ports, a plurality of direct current connection ports, a plurality of converter transformers, a plurality of converter valves, a plurality of direct current switches, a plurality of alternating current switches and a plurality of direct current transformers;

When a direct current fault occurs in a medium-voltage direct current bus, the device comprises:

9. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method of any of claims 1 to 7 when executing the computer program.

10. A computer readable storage medium, characterized in that the computer readable storage medium stores a computer program which, when executed by a processor, implements the method of any of claims 1 to 7.

11. A computer program product, characterized in that the computer program product comprises a computer program which, when executed by a processor, implements the method of any of claims 1 to 7.