JP2014241721A - Multiple terminal type electric power conversion device, electric power system and control program of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To subdivide an electric power circuit, develop a device which can interchange asynchronous electric power between them, and interchanges electric power via multiple routes to a destination as with in the Internet in order to suppress enlarging the possibility of the occurence of chain power outage due to the system being unstable from the change of a large amount of natural energy power source.SOLUTION: Chain power outage is reduced by inventing a multiple terminal type electric power conversion device which includes multiple semiconductor element structures for electric power capable of bidirectionally converting the electric power and connected to each other and distributes and supplies the electric power and by asynchronously connecting a subdivided electric power system. The electric power is interchanged to the target electric power circuit as with the Internet by assigning an address for information processing. Accordingly, electric power conversion related information and transaction related information are associated with each other, thereby allowing electric power transactions and derivative transactions.

Description

  The present invention provides a multi-terminal power conversion device between systems, which is necessary to prevent the spread of system fluctuations and chain power failure when a large amount of renewable energy with large fluctuations is introduced into the system, The present invention relates to a power system installed and configured and a program for controlling the power system.

  In recent years, the introduction of renewable energy power sources, such as wind power generation and solar power generation, is accelerating due to climate change problems and rising fossil fuels. The Japanese government has set a goal of introducing 28 million kW of solar power in 2020 and 53 million kW in 2030. This is equivalent to 25% of the current maximum power of 180 million kW in Japan.

  If the power supply of this size fluctuates due to the weather, it becomes difficult to maintain the frequency. Therefore, according to the “Study Group Report on Low-Carbon Electricity Supply System” in July 2009, the government would use 1% of solar power generation as of FY2020, even if it adopts a certain scale of output suppression. , Reported that only about 3 million kW (about 7%) can be introduced.

  In the United States, although it is different in each state, the introduction of 10-30% is planned in the next 10-20 years, and the plan to increase the transmission line capacity to maintain the frequency is examined in the promotion of smart grid. Yes.

  Even in Europe, although the introduction plans differ in each country, the EU directive aims to introduce 20% of renewable energy by 2020, but power flow fluctuations are expected to increase in order to maintain the frequency. Plans to strengthen the power grid are under consideration.

  However, in the recent example of a major power outage, the chain power outage in the northeastern United States on August 14, 2003 began with an operational error in Ohio and a malfunction in the alarm system. Began with a high-voltage line accident caused by the collapse of trees, and the 2006 catastrophic power outage spanning eight countries including Germany, France and Spain originated from the planned suspension of transmission lines in Germany.

  The mechanism of this chain power failure is that the power system is a huge synchronous system, so if an accident where the power flow cannot flow at any one place occurs, the power flow will be an unexpected burden on the system, If it becomes impossible to withstand, the system will stop, and the load of power flow will be extended to other systems, and the power outage will spread like a snowman.

  That is, as the transmission capacity of the power system is increased and the interconnection is strengthened, the possibility that a small accident or a small decrease in transmission line capacity will cause a chain power outage in a wider area.

  In order to prevent this, in Denmark, a proposal was made to divide the electric power system into voltage units and divide them into units called “cells”, in which fluctuations are absorbed. However, the control system alone cannot catch up with the spread speed of the chain if an accident actually occurs, and there is also a risk of causing a power failure in a healthy system if cooperative control is not successful.

  In the United States, the eastern, western, and southern systems are separated, and a large number of ultrahigh-voltage transmission lines are connected between them, and an AC / DC / AC power converter is placed in the middle of the transmission lines to accommodate power asynchronously. However, even the eastern part is about the same size as Europe, and it cannot prevent the catastrophic blackout that occurs in it.

  If the United States and Europe are separated into several hundreds of power grids each, and an inter-system power converter that can interchange power asynchronously between one's own power system and multiple neighboring power systems, an accident can occur. Even if a power failure occurs, the power failure can be limited to the power system that caused the accident, and a chain power failure can be prevented.

  If you use multiple power converters between multiple systems, many power routes are created, so even if you disconnect the system that caused the power outage accident, you can get power from many other systems little by little. And the surrounding system can maintain soundness.

  If your system can hold up, you can prevent the power failure from linking to the snowman. Since the power converter uses gate block control, the power can be cut off at a higher speed than a normal circuit breaker, so that the power fluctuation due to the accident can be suppressed to a small level.

  If there is an inter-system power converter, an existing transmission line can be used for connection to the surrounding power system. As a result, the facility utilization rate of the transmission line, which normally remains below 50%, is dramatically increased. In addition, reactive power can be freely accommodated and voltage adjustment can be performed.

  However, such a multi-terminal type power converter has not existed.

  The reason is that the conventional power system is expanding the synchronous system to average load fluctuations and stabilize the system, and it was not necessary to consider huge power generation fluctuations such as renewable energy There is.

  In the prior art, the following several proposals have been made as countermeasures for problems when a large number of unstable power supplies are connected to a synchronous system. They are roughly classified into the following three methods.

  The first conventional method is a method for strengthening the power backbone system. This is to strengthen the high-voltage interconnection line, install a BTB loop controller that performs AC / DC / AC conversion, increase the capacity of the frequency converter station, increase the capacity of the Hokkaido Honshu DC interconnection line, etc. It will prepare for fluctuations in renewable energy power sources by increasing turbine power generation and variable speed hydroelectric power generation facilities. The following Patent Documents 1 and 2 are related to this method.

  The second conventional method is to suppress output of the distributed power source and to suppress demand. As for output suppression, solar power generation and wind power generation are being considered to make a circuit to suppress output by a signal from an electric power company. The following Patent Documents 3 and 4 are related to this method.

  The third conventional method is a method of performing power interchange between a plurality of power systems and a backbone system. In this method, a plurality of power systems into which unstable power sources such as renewable energy are introduced in large quantities are connected by some form of power interchange device, and power is interchanged. There exist the following patent documents 5, 6, 7, and 8 in this method.

  Moreover, there exists the following patent document 9 regarding fusion of electric power and communication.

Japanese Patent Laid-Open No. 11-146560 JP-A-11-98694 JP 2008-182859 A JP 2007-189840 A JP 2003-324850 A JP 2007-89250 A International Publication No. 2004-073136 Japanese Patent No. 3934518 JP 2003-152756 A

  The first conventional method is aimed at strengthening the backbone system. For example, in Patent Document 1, a plurality of regional systems to be controlled are connected between the regional systems according to the system status at the control execution time. It is said that the stability of the electric power system is increased by freely changing the target system range using the on / off operation of the switch. However, the source of each regional system is the same synchronous system, and it is only a proposal to change the flow of the tidal current according to the change of the system constant. This method does not solve the problem when the number of renewable energy power sources that do not have synchronization power increases.

  Patent Document 2 proposes a power interchange command device in a power interconnection system in which a plurality of power systems are interconnected by a BTB type power converter. According to the specification, it is proposed to measure all demand and supply for each power grid in a power grid of multiple power grids, collect all the demand imbalance information in the center, and distribute power according to a predetermined share It has become.

  In the embodiment of Patent Document 2, it is feasible as a power interchange method between two systems such as Hokkaido-Honshu DC connection, but the number of target power systems, the number of consumers in them, and solar power In a power system where power generation facilities etc. increase rapidly and the power system configuration changes and increases rapidly, maintain a central control system that keeps track of all the demand and supply of multiple power systems for each power system. Is a very difficult task.

  The second conventional technique is suppression of output and demand. For example, Patent Document 3 proposes a wind power generation system that suppresses fluctuations in the output power of the wind power generator exceeding the maximum output capacity and charge capacity of the power storage device. ing. Further, Patent Document 4 proposes that the state of the system is constantly monitored, and when necessary, the control of the generator is combined with the suppression of the generator output to achieve finer control. In recent years, demand-side restraints have been developed mainly in the United States in terms of smart grids and smart meters. These methods are technologies for suppressing power generation or demand, and none of them are technologies for achieving the purpose of introducing a large amount of renewable energy power sources.

  In the third conventional method, a method is proposed in which power is interchanged between a plurality of power systems and a backbone system.

  For example, Patent Document 5 proposes “a power supply and demand adjustment system that controls power interchange by exchanging various types of information with each other via a communication network while allowing power interchange with each other via a transmission and distribution network”. doing. However, it is basically a method of frequently separating systems in a conventional synchronous system, and cannot be said to be a technique for achieving the purpose of introducing a large amount of renewable energy power sources.

  Japanese Patent Laid-Open No. 2004-228688 proposes system isolation and connection optimization using a loop controller, but it is also a method of frequently isolating a distribution network connected to a synchronous system.

  In these methods, since all electric power consumers basically depend on the main power system, the increase in the renewable energy power source does not answer the problem of weakening the synchronization power.

  Patent Document 7 proposes an “electric power system in which a plurality of electric power suppliers and electric power suppliers including electric power devices and electric power supply and demand control devices are interconnected, and which allows mutual power interchange”. It is a simple concept and has the following defects in electrical circuits.

  First, the interconnection line connecting multiple customers is "branched power supply / demand line, daisy-chain power supply / demand line, radial power supply / demand line, mesh power supply / demand line, or a combination of these" However, such a connection entails complicated tidal current problems at the same time, and at the same time increases the short-circuit capacity, leading to an increase in circuit breaker capacity and a complicated protection system. There is also a proposal to do this with a DC interconnection line, but this significantly increases the short-circuit capacity of the DC interconnection line, and the difficulty of designing the interconnection line, such as installing a DC breaker or dividing the line, is high. .

  In addition, in this proposal, a plurality of suppliers and demanders are connected to one track through power control devices. However, in order to allow power to be exchanged between the demanders and demanders, two power control devices pass through. The circuit is redundant and the loss increases.

  In addition, in order for multiple suppliers to supply and receive power without excess or deficiency on a single interconnection line, one of the supply and demanders becomes a voltage source, maintains the voltage of the interconnection line, and supplies power The supply and demander of this company supplies current according to this voltage, and the demander and demander who is in the position of receiving power receives current according to this voltage. When a time delay occurs in this control, the voltage source fluctuates greatly in such a small system, and shakes all the supply and demanders connected to this interconnection line. Since supply and demand of this system is performed via communication, the reliability depends on communication. Such an electric circuit configuration is not realistic.

  In patent document 8, the proposal which added the electric power storage apparatus to the direct current | flow multi-terminal power transmission which assumed several isolated islands etc. is performed. However, actual DC multi-terminal power transmission is limited. This is due to the fact that no effective means for controlling the total sum of power between a plurality of terminals to zero has been developed. The actual operating locations are limited to the SACOI project in Italy (200 kV, 200 MW, 3 terminals), which is an example of only 3 terminals, and the Quebec-New England project in the United States (450 V, 2,000 MW, 3 terminals). There is no plan. The latter was planned with 5 terminals, but the plan was reduced to 3 terminals due to controllability issues and the like, and bidirectional power interchange was limited to only one of them.

  According to this patent document, it is claimed that by taking in the power storage device, it can be stably operated with a plurality of DC multi-terminals. However, this system contains the following fundamental defects. First, since the distance length of the DC transmission line is increased, the probability of an accident at a DC cable or a connection portion is increased. If a large number of DC circuit breakers, etc. are not arranged at the branch point, the electric circuit cannot be separated when an accident occurs in the DC section, resulting in a power failure of the entire system. Further, the total power zero control between all terminals including the power storage device must be secured by a communication line, and the reliability of the control depends on the communication reliability. Although these problems are not related to the presence or absence of power storage, since the power storage becomes more complicated, it is practically impossible to realize DC power transmission with four or more terminals.

  As described above, there is no straightforward example in the prior art document regarding a power system for enabling mass introduction of renewable energy. What can be assumed with reference to prior art documents is that the current main power system is divided into a number of power systems composed of renewable energy power sources, distributed power sources and demands, and power storage devices are introduced to uniquely Stabilize frequency and voltage by balancing supply and demand (referred to as power system independence), and then connect to each other via interconnected devices such as BTB and loop controllers (hereinafter referred to as BTB-type interconnected devices). Up to the method of connecting with a line.

  However, the power network using the BTB type interconnection device has the following problems.

First, in terms of the power interchange control device,
First, the BTB type interconnection device requires an interconnection device of an order proportional to the square of the number of power systems to be linked.
Secondly, it is necessary to perform coordinated control in the meantime, which not only increases the number of converters but also creates a difficult problem of coordinated control between devices of different installation periods and manufacturers.
Third, when a plurality of power systems are continuously powered, there is a problem that power conversion is performed twice in a power system that only allows power to pass and conversion loss increases.
Fourthly, when a failure occurs in a power bus, there is a problem that all power interchange routes that pass through the power system are stopped and spread to a healthy power system.

In terms of communication systems,
First, in order to carry out power interchange among a plurality of power systems, as the number of network routes increases, the communication system becomes more complicated, requiring expensive initial investment and maintenance costs.
Secondly, the number of communication routes and communication devices that must maintain reliability becomes enormous, making it difficult to cope with modifications and new additions.
Thirdly, the realization of a new concept of accommodating power from any power device to any power device in another power system means that the conventional communication method has difficulty in handling facilities and the size of initial investment, There is a problem of increased maintenance costs.

Furthermore, in terms of the control system,
First, when performing such power interchange, the conventional method requires a central command device, and means for collecting information in the center, its communication circuit, and means for transmitting a command.
Secondly, in view of the importance of the reliability of the power supply system, measures such as duplication are necessary.
Third, in a new power system in which a plurality of distributed power system systems are constantly reorganized and increased, such conventional methods generate enormous capital investment and uninterrupted maintenance. The burden on the person becomes enormous.

  In addition, when conducting power interchange between multiple power systems, obtain information on the size, amount, time, and power price of active / reactive power that can be accommodated from all power systems, taking into account power route restrictions, It is necessary to select a route to be accommodated, determine a combination of a plurality of routes, and notify each of the accommodation devices for execution.

  Regarding the combined concept of the power network and the communication network, Patent Document 9 shows an example in which a power line and a communication circuit are integrated in a home or building. However, this is a concept of an Internet line using a power outlet. It does not include concepts related to control.

  From the above, in order to introduce a large amount of renewable energy, it is necessary to maintain a balance between the renewable energy and the supply and demand of power equipment such as other power sources / loads and power storage devices in each power system. It is necessary to develop an efficient interconnection device that can be connected asynchronously with other power systems, including the main power system, for the parts where shortages occur, and to control the power equipment and the overall control. It is necessary to construct a comprehensive power system that solves problems such as the development of efficient and flexible control systems, communication systems that serve as the communication infrastructure, and optimal power interchange algorithms.

  From the background as described above, the problem to be solved by the present invention is a power converter between multiple power systems that distributes and distributes power simultaneously to a plurality of power systems generated by subdividing an existing power system. However, an object of the present invention is to provide a system in which a “multi-terminal power conversion device” and a plurality of the multi-terminal power conversion devices are connected to each other so as to synchronize time and accommodate power to a distant power system.

  As a control method, an address is added to each converter and the entire multi-terminal power conversion system, and distributed information processing according to the Internet protocol is performed, so that a route for sending power is sent by Internet mail. The purpose is to provide an electric power system capable of routing, recording information of power transmission sources (power generation source, power generation amount, price, time, waypoint, loss, etc.), storing and conducting power transactions. .

  When replacing or repairing the power converter of a multi-terminal control device, the object is to provide means for continuing the operation of the remaining power converters without powering down all the devices.

  An object of the present invention is to provide means for providing a power supply or absorption means to the multi-terminal power converter itself and having a bus voltage maintaining function.

  Each unit of the multi-terminal power converter is built in a cabinet that can be pulled out, and has a structure in which multiple cabinets are built in one cubicle. By pulling out the cabinet, the input / output terminals of the unit and the common bus terminal are connected to the cubicle. By standardizing so that it can be disconnected from the input / output terminal side connection part and the common bus connection part, it is possible to perform attachment / detachment recognition such as plug and play, so that ad hoc expansion of power equipment is possible An object of the present invention is to provide a multi-terminal type power conversion device that is capable of generating maintenance work.

  An object of the present invention is to provide an electric power system that uses an existing power transmission line to connect a multi-terminal power conversion device, perform power interchange, and diversify power transmission routes.

  An object of the present invention is to provide an electric power system that uses an existing power transmission line to independently connect a multi-terminal power converter to each line of the power transmission line, diversifies the power transmission route, and improves the power transmission line utilization rate.

  An object of the present invention is to provide a power system that performs power transmission and power accommodation according to power route restrictions and converter capacity restrictions by cooperatively changing the operation modes of a plurality of multi-terminal power converters.

  An object of the present invention is to provide a power system that supplies not only active power but also reactive power and maintains voltage.

  The characteristic of electricity is that power generation and consumption are always the same amount at the same time, and the frequency cannot be maintained unless the power generation is increased or decreased in accordance with consumption with large fluctuations. If a large amount of natural energy power supply with large fluctuation is introduced here, fluctuation on the power generation side also becomes large, and it becomes difficult to maintain the same amount as a whole. Therefore, power transmission troubles are likely to occur, and once they occur, the troubles tend to expand in a chained manner. The challenge is to create a power system that reduces the possibility of a chain power failure due to an accident by creating a large number of subdivided power systems by dividing the asynchronous system with a multi-terminal power converter and asynchronously connecting them. There is to serve.

  In order to send power in a coordinated manner between a plurality of multi-terminal power converters, it is necessary to match the start-up / increase output rate / operation value / decrease output rate / stop timing of the power converter. This is called time synchronization.

There are roughly three methods for achieving time synchronization.
(1) Time synchronization is achieved with a high-speed communication line.
(2) The time of the control circuit of the corresponding power converter is set based on external clock data such as GPS and radio clock.
(3) Synchronize using a current waveform flowing through the power circuit and a voltage waveform applied to the power circuit.

The method (1) may be interrupted by a communication line or may have a lower effective speed due to the influence of other communications, and must be considered as a low-reliability method. A procedure for correcting the delay of the communication line is necessary, and its reliability is not sufficient.
The method (2) is less reliable when GPS or radio clock data cannot be acquired. Also, since data acquisition is not continuous but is usually performed intermittently, it is necessary to determine the time with the clock function of the self between acquisitions. For this reason, it cannot be said that the reliability is high. In the Internet world, Network Time Protocol (NTP) is a known procedure, but the communication line delay is corrected for synchronization and the reliability of the error is not sufficient.
The method (3) is an excellent method because the current and voltage flowing through the power circuit are propagated at the same speed as that of light, and thus there is no need to basically consider the time lag. However, the amount of information that this current waveform or voltage waveform (hereinafter referred to as an electrical waveform) can be transmitted is small, and the power conversion start time, end time, power conversion size, price, power generation source, power transmission source, via I can't fully convey information about the ground.

  In the method (3), it is possible to increase the amount of information by making the current waveform and voltage waveform flowing through the power circuit into a special shape or combining them. However, when the amount of information is increased, the transmission distance is shortened.

  The problem is to provide a power system that solves the above time synchronization problem.

  Electricity is said to have no color, and it has been impossible in the past to identify electricity. However, if the identification becomes possible, power trading and value-added trading become possible.

  The challenge is to identify electricity and manage the records centrally.

  Also in software, it has been customary to develop individual software corresponding to individual devices and devices in power-related devices and devices.

  The challenge is to provide a power system that is always up-to-date with software common to all power devices.

The invention according to claim 1, which has been made to solve this problem, a multi-terminal power conversion device, and three or more self-commutated power converter for power conversion bidirectionally, each Measured by a voltage / current measuring device for measuring the voltage / current passing through the self-excited power converter, a common bus connecting one terminal of the self-excited power converter in parallel, and the voltage / current measuring device. Voltage, current, power, frequency, and phase are calculated based on the measured values, one of the self-excited power converters maintains the voltage of the common bus, and the other self-excited power converter is the self-excited type. A plurality of the self-excited powers that maintain the voltage or current of the connection destination to which the other terminal of the power converter is connected, so that the sum of the power flowing into the common bus and the power sent from the common bus becomes zero The self-excited type by controlling the converter in cooperation Characterized by comprising a power control system for controlling the self-commutated power converter as the other terminal of the force transducer is power interchange asynchronously between connected connection destination.

  The effects of the present invention are as follows for each claim.

The effects of the invention according to claim 1 are as follows.
First, a multi-terminal AC-DC converter group is represented as ACs-DC-ACs (s indicates a plurality of AC terminals). Since this system configuration is installed as an integrated system in the substation premises, it becomes easy to grasp the operation status such as DC voltage, current, and control angle of a plurality of converters, and to perform intensive control and protection. Start and stop all converters at once, start and stop them individually, coordinated control system to prevent excess or deficiency of power between converters, and control in concert when power flow is reversed The tidal current reversal method and the system that centrally protects the entire system in the event of a failure or accident have the advantage that it can be centrally managed in one place.
In addition, by connecting the external terminal of the multi-terminal power converter directly to an existing AC transmission line without installing a new transmission line or DC interconnection line, Even when the frequency and phase are different, active power of an arbitrary magnitude can be actively transmitted / received simultaneously from one system to a plurality of systems, or transmitted / received from a plurality of systems to a plurality of systems.
Furthermore, the use of the power semiconductor element dramatically increases the power interruption speed as compared to the conventional circuit breaker. As a result, even when solar power generation or wind power generation covers the majority of power demand, the power system is subdivided and the multi-terminal power conversion device of the present invention is used for the connection between the power systems. By doing so, the possibility of causing a chain blackout can be reduced.

The structure of a multi-terminal type power converter is shown. (Examples 1 and 2) It shows the accident protection system and switching procedure. Example 1 The operation procedure of the device operation system according to the state of the connected power system is shown. Example 1 2 shows a LAN / WAN configuration of a communication control system. Example 1 The relationship between the simple figure and detailed drawing of a multi-terminal type power converter is shown. (Example 3) The structure of a bypass circuit and a power storage device connection circuit is shown. (Examples 3 and 4) 1 shows a drawer configuration of a multi-terminal type power converter. (Example 5) The power system connection structure of a multi-terminal type power converter is shown. (Examples 6, 7, and 10) This shows the independent operation method for existing transmission lines. (Example 7) This shows the independent operation method for existing transmission lines. (Example 7) It shows about superposition type power transmission. (Example 8) This shows the time-sharing transmission. (Example 8) This shows multi-route power transmission. (Example 8) This is an illustration of virtual transaction accommodation. (Example 8) This is an illustration of virtual transaction accommodation. (Example 8) This is an illustration of virtual transaction accommodation. (Example 8) This shows the difference in power interchange between ordinary power systems and power conversion. Example 9 It shows the principle of power interchange through power conversion. Example 9 The principle of the time synchronization method is shown. (Example 11) An example of an electric power transaction book is shown. (Example 12) This is an example of disassembling the actual power accommodation into accommodation parts. (Example 12)

  In the present embodiment, an embodiment of the invention according to claim 1 will be described.

  FIG. 1 illustrates the structure of a multi-terminal power converter 1. The multi-terminal power converter includes an A input / output terminal 201 composed of a circuit breaker 8, a disconnector 9, and a self-excited power converter 10, and a B input / output terminal 202 composed of a circuit breaker 8 and a disconnector 9. . First, FIG. 1 shows an example in which the power line carrier communication terminal station 13 is used, but this is not necessary when an external data network is used. The voltage / current / power measuring device 16 includes a type that calculates power based on voltage / current and a type that installs a dedicated power measuring device. Moreover, the measuring device 16 has a thing installed in a direct current bus, and a thing installed in an alternating current side, and a type differs, respectively. This measurement can also be used for power trading. It is also possible to prepare a separate dedicated power meter for trading. This power record is stored in a dedicated recording device 161 and used for power transactions.

  In FIG. 1, the common bus is a direct current, but the common bus may be an alternating current. There is also a form using a power conversion circuit such as a matrix converter or a triac. The DC voltage stabilizing capacitor 17 is used when the parallel type common bus 18 is DC.

  The configuration of the A input / output terminal 201 in FIG. 1 includes a mechanical disconnector 9 that can cut a circuit, a circuit breaker 8 having a necessary breaking capacity, and a self-excited bidirectional power converter 10. The configuration of is composed only of a mechanical disconnector 9 capable of cutting a circuit and a breaker 8 having a necessary breaking capacity. There are three types of the multi-terminal type power converter 1, one having both A and B input / output terminals, one having only A input / output terminals, and one having only B input / output terminals.

  At least one of the A input / output terminals is connected to the power system in which the multi-terminal type power converter is installed, and after converting the power of the power system to DC, the remaining A input / output terminals are connected. Inverts and sends out power in synchronization with the voltage, phase, and frequency of the previous power system, or conversely, multiple A input / output terminals forward-convert power and back-convert to that power system for power Can be sent. Control is performed so that the sum of the inflow power and the output power between the A input / output terminals becomes zero.

  It is possible to connect a power storage device or a secondary battery to the common DC bus 18. In this case, charging / discharging control of the power storage device and the secondary battery may be incorporated in the input / output power total zero control of the DC bus. An electric power storage device or a secondary battery can be placed on the connection side of the A input / output terminal, and charging / discharging can be performed by controlling the converter of the A input / output terminal.

  The B input / output terminal is an input / output terminal that is paired with the A input / output terminal of another multi-terminal type power converter installed in the previous power system connected via the interconnection electric line.

  If a plurality of A input / output terminals of one multi-terminal type power converter are connected to the own system, the power capacity transferred by the own system can be increased.

  If the A input / output terminals of a plurality of multi-terminal type power converters are connected to the own system one by one, the power capacity delivered and received by the own system can be increased and the number of connected power systems can be increased.

  The forward conversion side of the self-excited power converter of the A input / output terminal is connected in parallel with a DC bus and has a capacitor for maintaining the voltage. The reverse conversion side of the power converter is connected to the AC power system. In the case, it has an AC reactor or AC transformer and the necessary AC filter, and when the connection destination is a DC power system, it has a smoothing capacitor.

  As shown in FIG. 1, the power control system includes a terminal control system comprising DC voltage, AC voltage, active power, reactive power, current, phase synchronization, and PWM gate control of each A input / output terminal, and start / stop / input It is possible to provide a power control system including a common control system including output terminal receiving / transmitting power setting and total power cooperative control.

  Each terminal of the multi-terminal type power converter 1 may be different in capacity. If the capacity is the same, the control constants can be unified, and there is no restriction on power distribution, which is efficient. For power transmission / reception, power can be equally distributed to all terminals, different power can be distributed, or time sharing can be performed while observing the usage status of the interconnected electric lines.

  As the power trading system, a power trading recording device 161 for recording the value of the power meter 16 of each A input / output terminal and the power interchange profile data so that it can be used for trading of electric energy can be provided. The watt-hour meter has a structure in which automatic calibration can be performed at any time by operating a power converter with software described later. To measure the amount of electric power, a voltage / current measuring device used for control can be used, or the data can be used for calculation.

  By combining power converters in this way, combining a unit that maintains DC voltage and a unit that controls power, and controlling all power in and out by a central processing unit installed in the system, multiple power A multi-terminal power conversion system that allows power to be distributed and distributed to the system can be constructed.

FIG. 2A illustrates an accident protection system. It is possible to have a power interchange route protection circuit that secures the maximum power interchange route by having the following components and cutting off the minimum necessary circuit.
Fig. 2 (A-1) I / O terminal overcurrent protection circuit: When the current exceeds the set current at each I / O terminal, at the A I / O terminal, the gate block and circuit breaker open operation, B I / O terminal In I / O terminal protection circuit that opens the circuit breaker.
Fig. 2 (A-2) DC bus protection circuit: Power to perform gate block of all power converter with time limit when DC current meter is installed in DC section of each A input / output terminal and total current of all terminals is not zero Converter DC bus protection circuit.
Fig. 2 (A-3) Multi-terminal type power converter protection circuit: When a power meter is installed in each input / output terminal receiving unit connected to the power system and the total power of all terminals is not zero, all input / output terminals are timed Multi-terminal power converter protection circuit that opens the circuit breaker.
FIG. 2B-1 and FIG. 2B-2 illustrate input / output terminal switching at the time of an accident. When power is exchanged from the top terminal to the second terminal as shown in FIG. 2 (B-1), the top terminal is overcurrent or the like as shown in FIG. 2 (B-2). Can be switched to supply power from the fourth terminal to the second terminal by quickly turning on the gate block of the power converter of this circuit. Furthermore, it is possible to disconnect only the input / output terminal where the accident occurred with the circuit breaker 8 or the disconnector 9 and to continue the power interchange with the other input / output terminals. The I / O terminal where the accident occurred can be restarted as soon as it is restored. When the abnormality is recovered only by the gate block, it is possible to return to the initial state without performing unnecessary blocking.
As shown in FIG. 2 (A-4), the control method is such that the sum of the power flowing in from the input / output terminal and the power flowing out becomes zero. For this, the most common method is that a unit other than the DC voltage maintaining unit inputs and outputs the requested power, and the DC voltage maintaining unit compensates for the excess or deficiency of the power.

  In addition, as will be described later, when connecting the power storage device to the DC bus, all the units input and output the requested power, and the power storage device compensates for the excess or deficiency of the power while maintaining the DC voltage. It can be a control method.

  As shown in FIG. 3, as a device operation system, when the input / output terminal is synchronized, the disconnector 9 is closed and the voltage, frequency, and phase of the connection destination are measured, and when the connection destination has a voltage (independent), A parallel synchronous operation (system interconnection operation mode) is performed to close the circuit breaker 8 after synchronizing the voltage, frequency, and phase of the power converter 10 (FIG. 3 (A)). After the voltage / frequency conforming to the pre-rating is created by the power converter 10, the circuit breaker 8 is closed, and a self-sustaining operation input operation circuit (self-sustaining operation mode) for supplying power to the connection destination is performed (FIG. 3 (B )) A device operation system can be provided.

  In the present embodiment, an embodiment of the invention according to claim 2 will be described.

  First, based on FIG. 4, the structure of the communication system of this invention is demonstrated. A communication terminal station (data terminal end: DTE) installed at the A input / output terminal and the B input / output terminal of the multi-terminal type power conversion device acquires information related to power and transmits it to the CPU, as well as an external data communication path or power line. Signals are exchanged with the outside using the carrier communication path as a data communication path. As the external data communication path, an optical cable, a LAN cable, a metal cable, a wireless cable, or a coaxial cable can be used.

  FIG. 4 shows a power device control terminal device added to provide a communication address to the multi-terminal type power conversion device main body and its input / output terminals to configure the WAN and control the output of the electrical devices in the power system. 1 also illustrates a system in which a communication address is given and a LAN is configured, the two are connected, and communication is integrated. This makes it possible to communicate between different power system power devices or between multiple power systems, and build a power system that can give control instructions related to power interchange to the input / output terminals of the multi-terminal power converter it can.

  An address server holding an address table describing the MAC address specific to the input / output terminal, the assigned IP address, the subnet mask, and the default gateway is placed in the WAN, and the MAC unique to the power device control terminal device is placed in the LAN. If an address server that holds an address table that describes addresses, assigned IP addresses, subnet masks, and default gateways is placed, the multi-terminal asynchronous interconnection device input / output terminals and power equipment using the TCP / IP communication protocol A power network system characterized by communication between control terminal devices can be constructed.

  When power line carrier communication is used as a communication path, a WAN / LAN is constructed using a communication line or power cable as a transmission path for communication signals. Match. If the electric line is disconnected or the related equipment is stopped, the communication circuit is also released or stopped, so that no communication signal flows through the circuit. As a result, the latest state of the power system can be grasped without checking the complicated state. In the 66 kV transmission line, a digital power line carrier of 192 kbps has already been put into practical use. The amount of information of a power interchange signal, which will be described later, needs only about several kilobits for all communications, so the band can be said to be a sufficient speed.

  Multi-terminal power converters, like Internet routers, can exchange information between multi-terminal power conversion systems and always know the addresses of adjacent multi-terminal power conversion systems and their input / output terminals. The necessary power can be sent to a distant power system while converting the power like a bucket relay, and the necessary routing information can be always grasped.

  This is a distributed control method compared to a method in which the conventional power interchange mechanism collects all information in a common center such as the central power supply command center and all commands are issued from there. The present invention proposes a specific means for realizing the concept.

  In addition, the multi-terminal power conversion system of the present invention is arranged adjacent to a section of the substation, and the information necessary for the control is controlled by the central processing unit to control the gate of the power semiconductor element. The storage device is characterized in that the power conversion related information and the transaction related information are associated and digitally recorded.

  In the present embodiment, an embodiment of the invention according to claim 3 will be described.

  FIG. 5 illustrates a simple illustration of the power conversion circuit expressed in FIG. The AC / DC conversion circuit is represented by a black triangle. The top of the triangle represents the DC side, and the base of the triangle represents the AC side.

  FIG. 6A shows a four-terminal multi-terminal power converter, but the number of terminals is not limited to this.

  Although FIG. 6A shows an example in which bypass circuits of circuit breakers and disconnectors are installed at all locations where any two of the four terminals are connected, the form of the bypass circuit is not limited to this. is not.

  In the present embodiment, an embodiment of the invention according to claim 4 will be described.

FIG. 6B shows an example in which the power storage device is directly connected to the common bus when the common bus is direct current in the multi-terminal power conversion device, and FIG. 6B-1 shows the DC / DC converter. FIG. 6B-2 shows an example in which the connection is made via.
As a result, necessary power can be supplied to the common bus or excessive power can be absorbed.

  The multi-terminal power converter device can use the following control method. If you do not have a power storage device, one of the input / output terminals will maintain the DC voltage of the common DC bus, the other terminal will perform active power control, and the DC voltage will be maintained at the part where the sum is excessive or insufficient. A common method is to make up for the input / output terminals.

  When the power storage device is connected to the common bus, since the DC voltage is maintained by the power storage device, all input / output terminals can perform active power control. The power storage device will compensate for the excess or deficiency.

  In this case, since the overcharge / overdischarge may occur unless the charge amount of the power storage device is accurately grasped, the charge amount measurement system is important.

  When the power storage device is a secondary battery, the DC voltage often changes due to a change in the charge amount (SOC) of the battery. In this case, in order to connect to the DC common bus, it is necessary to maintain the voltage of the DC bus as in the case of (B-2).

  When the power storage device is a secondary battery, the DC voltage does not change so much due to the change in the battery charge (SOC). In this case, in order to connect to the DC common bus, the case of (B-1) can be directly connected to the DC bus.

  In the present embodiment, an embodiment of the invention according to claim 5 will be described.

  FIG. 7 shows a multi-terminal type power conversion device in which each unit is built in a cabinet that can be pulled out, and a plurality of cabinets are built in one cubicle. An example is shown in which the busbar terminal can be disconnected from the input / output terminal side connection portion and the common busbar connection portion in the cubicle. By standardizing such a structure so that plug-and-play-like attachment / detachment recognition can be performed, ad hoc expansion of power equipment is possible, and maintenance activities can be made easier. Power system can be provided.

  FIG. 7 shows a state in which the fourth input / output terminal from the top is pulled out from the multi-terminal power conversion device 1.

  Each input / output terminal and the power storage device unit are connected to a common bus with an insertion terminal. This structure is the same as that normally used in metal clad switchgears for power systems.

  When pulling out, an interlock structure is incorporated in which the power conversion element is gate-blocked, the circuit breaker is opened, the disconnector is opened, and the electric shock is not generated and can be pulled out.

  A disconnector is good also as a structure which serves as disconnecting by pulling out. The circuit breaker can be replaced by a gate block. In that case, the disconnecting device 9 and the circuit breaker 8 in the drawing can be omitted.

  Similarly, the circuit of the power storage device can be pulled out. In this case, since an accessory such as a capacitor may be charged, an interlock mechanism that can be pulled out after confirming no voltage is incorporated.

  In the present embodiment, an embodiment of the invention according to claim 6 will be described.

  FIG. 8 illustrates a state in which the multi-terminal power conversion device of the present invention performs power accommodation by connecting input / output terminals of the device to a plurality of power systems. In FIG. 8, the connection is made to all five power systems through all combination routes. However, not all are necessary, and one power conversion element is required for one route. Absent.

  In FIG. 8, the A input / output terminal 201 with the power converter and the B input / output terminal 202 without the power converter are paired, but this is not necessarily required.

  Since the power converter is capable of grid-linked operation and independent operation, in such a power system, when any power system goes into a total power failure, it can be provided as a voltage source for restoration. Accident recovery is facilitated by proceeding with recovery by connecting the power supply in the power system to this voltage source. In this power system, there are a plurality of power supply routes at this time, which is advantageous for a recovery operation in the event of an accident.

  When the power system is separated from another power system for some reason, if the power generation and consumption of the power system are approximately equal, there may be a phenomenon of isolated operation in which the power system continues to operate independently. Even if the operation becomes independent, if a time synchronization electric waveform described later is constantly detected, it is possible to determine that the operation has become independent when the time synchronization cannot be detected.

  This is a phenomenon that becomes a problem because there is an accident that an electric shock is not noticed by the worker because there is a voltage in the downstream even though the upstream has a power outage in the synchronous system that flows power from upstream to downstream It is.

  In the power system proposed by the present invention, since there are a plurality of power supply routes, it is difficult to operate independently, and the power system is an asynchronous interconnection that can accommodate power even if the power systems are not synchronized. There is also a voltage. Work safety should be implemented based on the principle of no-voltage confirmation.

  In the present embodiment, an embodiment of the invention according to claim 7 will be described.

  FIG. 9 shows an example in which the input / output terminals of the multi-terminal power converter are independently connected to each line of the transmission lines that are operated in parallel with an even number of lines, and independent power interchange operation is performed for each line. It is shown.

  In a transmission line in a normal synchronous system, in an extra high voltage system exceeding 6,000 volts, power is generally transmitted in two lines. One line is installed on each side of the transmission tower and is laid to the same destination. Assuming that the capacity of the transmission line is 100%, both lines are operated in parallel to bear 50% each. However, the rated capacities are 100% capacity assuming that there is only one line in the event of an accident. Therefore, the normal transmission line utilization rate is 50% or less.

  FIG. 9A shows an example in which power is transmitted to three power systems A, B, and C. In this example, for simplicity, 100% of power is transmitted from A to C, and two transmission lines are both operated in parallel at 50%.

  FIG. 9B is an example of independent operation of each line of the transmission line in the power system of the present invention. The route drawn at the top of the two transmission lines can transmit power from the power system A to the power system C with 100% capacity. The route depicted in the lower part of the two transmission lines allows power to be transmitted from the power system A to the power system B with 100% capacity. It is also possible to transmit power from the power system B to the power system C with 100% capacity. Each power converter is rated according to its transmission capacity.

  Assuming that 100% of power is transmitted from the power system A to each power transmission route, if the upper route is stopped, the power system C becomes insufficient in power, but the power system B increases the output power. 100% can be backed up on the route to system C.

  Similarly, if the lower route stops, the power system B becomes insufficient in power, but the power system C can increase the output and back up 100% with the route to the power system B.

  In either case, the burden on the power system to be backed up is large, but due to the widespread use of secondary batteries and the like, short-time backup is sufficiently possible with current technology. This method is more likely than the increase in transmission lines.

  FIG. 10 illustrates the case of four power transmission lines. In this example, there are six wires on both sides of the transmission line. In general, the destinations are often different for each two lines, but the part that passes through a common route is illustrated.

  FIG. 10 shows an example in which the power transmission route of the fourth round from the power system A goes through the power systems B, C, D, E, and F. In this example, the place where the line is directly connected to each power system from each power transmission tower is disconnected or the circuit breaker 9 is installed for open operation. You are pulling into the device. In the multi-terminal power converter, independent operation is performed asynchronously for each input / output terminal.

  In the line 1, as is clear from FIG. 10, between the power systems A and B, between the power systems B and C, between the power systems C and D, between the power systems D and E, between the power systems EF and F, the power system F- This means that a power interchange route between power systems connected to the line 1 has been established.

  As is apparent from FIG. 10, the line 2 has power interchange routes between the power systems A and C, between the power systems CE and between the power system E and the power system to which the line 2 is connected.

  As is apparent from FIG. 10, in the line 3, the power interchange route between the power systems A and D and between the power system D and the power system to which the line 3 is connected has been established.

  As is apparent from FIG. 10, in the line 4, power interchange routes between the power systems A and F and between the power system F and the power system to which the line 4 is connected have been established.

  The method of creating a power interchange route is not limited to the above example, but should be considered on a case-by-case basis.

  Since the power interchange route created by this is asynchronous interconnection, it becomes a route that can send and receive active power and reactive power of any size, and if the power system has the remaining capacity, Can be used up to full rated capacity.

  The fluctuation at the time of the accident can reduce the influence on the power system by the high-speed gate block of the power converter. As for excess and deficiency of power, backup of power storage devices and the like may be required, but it is easier to make capital investment than enhancing transmission lines.

  The power accommodation route obtained by such a device constitutes a power network similar to the power accommodation route of FIG.

  In the present embodiment, an embodiment of the invention according to claim 8 will be described.

  Among them, an electric power system has been devised that enables five electric power interchange methods of superposition type electric power transmission, time sharing power transmission, multi-route power transmission, power compression accommodation, and virtual transaction accommodation.

  FIG. 11 shows that a multi-terminal type power converter is installed in each substation lead-in part of a transmission line, performs information communication between the devices, and simultaneously transmits different power to a plurality of substations using the same transmission line. The superposition type electric power transmission is explained. There are power systems 1, 2, and 3, with a converter 12 and a converter 23 respectively. When the converter 12 sends the power of W1 and W2 per unit time to the power system 2, and the converter 23 sends the power of W2 per unit time from the power system 2 to the power system 3 at the same timing, the power system 2, the power of deduction W1 is sent. The destination information header instructed to send the power of W1 + W2 and W2 to the converter 12 and the converter 23, respectively, is sent as a signal, so that such power interchange is possible.

  FIG. 12 illustrates time-sharing power transmission in which different power is divided and sent to different substations. 8 has a power system and a power converter similar to those in FIG. 8, but the converter 12 first receives a destination information header instructing to send out W1 power per unit time, and sends W1 to the power system 2. . At this time, the converter 23 is not operating, so that no power is accommodated in the power system 3. Next, a destination information header for sending W2 power per unit time to the power system 3 gives instructions to both the converter 12 and the converter 23, and both converters are simultaneously operated at the size of W2. As a result, W2 is sent from the power system 1 to the power system 3. At this time, the electric power system 2 only passes electric power. In this way, power can be accommodated for different purposes at different times.

  The advantage of this scheme is that power can be sent to different destinations at different times at the maximum output of the converter. This is similar to the concept of packet in communication, and can be called packet power. The amount of electric power for a certain time can be handled as a unit at the maximum output of the converter. This can also be called digital power.

  FIG. 13 illustrates multi-route power transmission that uses a plurality of different power transmission circuits to simultaneously send different power to one substation. 11 and 12, there are the power converter 12 and the power converter 23 between the power systems 1, 2, and 3, but there is also a power transmission route between the power systems 1 and 3 and conversion between them. There is a vessel 13. In this example, information is given to send power W1 to both power converters 12 and 23, and information is given to converter 13 to send power W2. As a result, the power of W1 + W2 is sent to the power system 3 from the power system 1 via different routes.

  FIG. 14 illustrates power compression accommodation that reduces power conversion and transmission loss by combining or canceling power transmission amounts by combining power transmission requests in the reverse direction. In the example shown in the figure, W1 (kW) is sent to the # 1 to # 4 power system via # 5, and W1 (kW) is sent to the # 7 to # 1 power system via # 5. ing. In this case, as is apparent from the figure, the power of W1 and -W1 flows between # 1 and # 5, which cancels out, so the power converters of # 1 and # 5 do not operate. It will be good. Thereby, a power conversion loss and a power transmission loss are reduced.

  Loss can be minimized by actively combining such power interchange plans. If each power system has a power storage device, it can be adjusted by shifting the time or adjusting the output. When information such as a power generation source is added to power energy, such a reverse power transaction may occur. In some power systems, wind power generation power is required, and the power system with wind power generation, on the contrary, requires power derived from cheap fossil fuels. .

  FIG. 15 illustrates the virtual transaction interchange of power between the power systems that are not connected to the transmission line when the power storage device is used.

  In FIG. 15, there are an electric power system A and an electric power system B, and no interconnection line is connected. The electric power system A has only the photovoltaic power generation PV, and the electric power system B has only the diesel power generation DG. The DG power is supplied to the customers of the power grid A by virtual power transactions in which the power storage amount in the power storage device (A) and the power storage device (B) installed in each is performed in the order from t0 to t2. An example in which PV power can be sold to a customer of the power system B will be described.

  At time t0, power storage devices A and B are charged with PV-derived power and DG-derived power, respectively.

  At time t1, the same amount of DG and PV are virtually exchanged between the power storage devices. This transaction is preferably accompanied by a bond-like form or means such as bills, certificates or cash settlement.

  At time t2, DG power can be sold in the power system A and PV power can be sold in the power system B. As a result, it is possible to carry out virtual transaction accommodation even when power is not actually transmitted.

  When trading the same amount of DG and PV at time t1, there is a way of thinking that the amount of power is the same amount and a way of thinking that the amount is the same amount. It is also possible to trade the difference in a different form without making the same amount. You can also trade futures on bonds and make derivative products.

  FIG. 16 illustrates virtual transaction accommodation when both power systems have PV, DG, and power storage.

  Up to time t2, the same as described above. At time t3, since each has DG and PV, it generates power and charges each power storage device. If the DG of the electric power system A and the PV of the electric power system B are virtually exchanged again at the time t4, it returns to the same state as that at the time t0, and different systems of electricity can be sold to each customer.

  In the present embodiment, an embodiment of the invention according to claim 9 will be described.

  First, the difference between power interchange in a conventional AC synchronous system and power interchange by power conversion, which is the basic principle of the present invention, will be described.

  FIG. 17A shows a conventional AC synchronous system in which four power systems (referred to as nodes 20) are connected by six interconnection electric lines (referred to as links 21). The interconnection line has a reactor component 19 of line inductance L. FIG. 17B is an AC asynchronous system according to the present invention, in which four nodes are similarly connected by six links via the A input / output terminals and B input / output terminals of the multi-terminal type asynchronous interconnection device. is there. For simplicity, the AC filter, connecting reactor or transformer are omitted in the figure.

  The initial state of the circuit network in FIG. 17A is synchronized with voltage V, phase 0, and frequency ω / 2π. In order to send power to the node c from this state, either the voltage of the node c is lowered or the phase is delayed by θ. If the normal voltage is lowered, the power equipment in the power system is adversely affected, so the phase is delayed. When the phase of the node c is delayed by θ, a phase difference θ is generated between all the adjacent nodes a, b, and d. As a result, the flowing currents are Idc, Iac, and Ibc, and these currents have the same magnitude. Since the voltage is the same, the incoming power is the same. That is, power is received from three nodes. This is the same even if the voltage V is changed without changing the phase. That is, in the AC synchronous system, it can be seen that when one node transfers power, it always affects adjacent nodes.

  In the initial state of the circuit network in FIG. 17B, the magnitude of the voltage V is the same among the four nodes, but the frequencies are different from ωa / 2π, ωb / 2π, ωc / 2π, and ωd / 2π, respectively. , Not synchronized. Initially, it is assumed that all bidirectional power converters 10 are stopped (black triangle state). In order to send power to the node c from this state, the power converter connected to the node a and the power converter connected to the node c are operated (white triangle state) here. Thus, as shown in the figure, only the power converter connecting node a and node c is operating, and all the other power converters are stopped. Therefore, power is interchanged only between the links ac, and the other nodes b and d are not affected at all.

  The state of the voltage / current vector at this time is shown in FIGS. 18 (A) and 18 (B), respectively.

FIG. 18A shows a case of an AC synchronous system corresponding to FIG. The nodes a, b, c, and d have the same voltage V, and the vector diagram when the phase is delayed by θ only for the node c is shown. At this time, a voltage difference ΔV is generated at both ends of the line reactor (L) between the links ac, bc, and dc, and a current I having a magnitude of ΔV / ωL (= Iac = Ibc = Idc) is 90 in the phase of ΔV. Flowing late. In FIG. 18A, since the voltages V of the respective vectors are equal, the triangle formed by the voltage vector is an isosceles triangle and the current phase is θ / 2.
I = ΔV / jωL = (V−V · e ^jθ ) / jωL
The complex power flowing into the node c is as follows because I of the same magnitude flows from the three directions of the nodes a, b, and d.
P + jQ = V · 3 · I ^* (where I ^* is a conjugate complex number of I)
= V · 3 · V (1-e ^−jθ ) / (− jωL)
= 3 · (V ² / ωL) · j (e ^−jθ −1)
= 3 · (V ² / ωL) · sin θ + j · 3 · (V ² / ωL) · (cos θ−1)
On the other hand, FIG. 18B is a case of an AC asynchronous system corresponding to FIG. The power at node a is forward converted to direct current by the power converter. Subsequently, it is inversely converted to AC Vinv synchronized with the frequency ωc / 2π of the node c. When the magnitude of the complex voltage Vc at the node c is V and the phase is 0, the complex voltage Vinv can take an arbitrary value by the PWM signal applied to the power converter. If the magnitude of Vinv is Vx and the phase difference from Vc is φ and synchronized with Vc, the reactance of the transformer or reactor between Vinv and Vc is L, and the voltage of ΔV is applied to both ends thereof. A difference occurs. That is, if Vinv = Vx · e ^{(jωct + φ)} , Vc = V · e ^jωct , and ΔV = Vc−Vinv,
The current I flowing through the reactor L is
I = ΔV / jωL = (V−Vx · e ^jφ ) / jωL
The power that can be exchanged is
P + jQ = V · I ^*
= V · (V−Vx · e ^jφ ) / (− jωL)
= V · Vx · sinφ / ωL + j · (V ² −V · Vx · cosφ) / ωL
It becomes.

  As described above, since the voltage magnitude Vx of the complex voltage Vinv and the phase difference φ between Vinv and Vc can be made arbitrarily, the magnitude and direction of exchange of active power and reactive power can be arbitrarily designed.

  In a general synchronous system, there is a certain relationship between active power and reactive power generated by a generator, and they cannot be generated independently of each other. Accordingly, voltage adjustment is performed by creating reactive power by putting capacitor equipment in the system separately from generating active power and adjusting frequency. On the other hand, the multi-terminal power converter of the present invention can supply both active power and reactive power simultaneously in an arbitrary size with one input / output terminal.

  In the present embodiment, an embodiment of the invention according to claim 10 will be described.

  This will be described with reference to FIG. Considering an example in which the existing electrical system is subdivided into # 1 to # 5 power systems as shown in the figure, the multi-terminal power converter of the interconnected portion is connected as shown in FIG. . If an accident occurs in the # 2 power system and a power failure occurs, the power converter connecting the # 1 and # 2 power systems detects the power outage at high speed and the # 2 power system side Stop the power converter. As a result, the power converter on the # 1 power system side and the power converters connected to the # 1 to # 3, # 4, and # 5 power systems can continue to operate.

  When the # 2 power system causes an accident, the # 3, # 4, and # 5 power systems are affected by the accident because the multi-terminal power converter installed on the # 2 power system side stops at high speed. Almost no need. The power that has been accommodated in the other system via the # 2 power system is promptly changed to accommodation using another route.

  In the present embodiment, embodiments related to claims 11, 12, and 13 will be described.

  These inventions relate to a plurality of power converters arranged between a plurality of power systems, a time synchronization electric waveform propagating on a power line created by the power converter, and a time synchronization transmitting the meaning of the electric waveform. The time synchronization information transmission network system is characterized in that time synchronization among a plurality of power converters is achieved by combining both the electronic information and the electronic information.

  According to the present invention, a plurality of power converters can be operated at the same size or stopped at the same time by combining a relatively small amount of information contained in the electric waveform appearing on the power line and a large amount of electronic information explaining its meaning. It is possible to change the size on the way.

  In FIG. 19, by driving the converter 12 and the converter 23 at the same timing and the same magnitude between the power systems 1, 2, and 3, the power system 2 is not sent power or is not received. 2 shows that power can be sent from the power system 1 to the power system 3. This is called time synchronization.

  In this way, since the amount of information that can be put on the voltage waveform is limited, the power converter is prepared for operation by transmitting in advance the meaning of small information via another external data communication path. A way to go is conceivable. This is a method of achieving time synchronization by a combination of the time synchronization electric waveform and the time synchronization electronic information according to the present invention.

  In FIG. 19, a signal is placed on the voltage waveform, but the peak of the voltage waveform has a lot of noise, so the timing for placing the signal can be zero cross where the voltage is zero. Moreover, a power line carrier communication signal can be put on the voltage waveform. Instead of putting a signal on the voltage waveform, a signal can be put on the current waveform. It is also possible to have the signal generated by the power converter itself.

  The electrical waveform for time synchronization is not limited to one, and it can be given meaning as a combination of several electrical waveforms. If a combination is used, time synchronization can be achieved using only the electrical waveform for time synchronization. For example, by using two or more electrical waveforms to generate a warning signal before a certain cycle of driving start, preparation is performed, or by changing the number of cycles to be spaced to make a countdown signal, the timing of driving start is matched You can do that.

  In addition, there is a method of synchronizing time by using GPS time information or a radio clock signal as time synchronization electronic information to synchronize the clock of the multi-terminal power interconnection device. In this case, an electric waveform for time synchronization is not necessary.

  In the invention which concerns on Claim 11, multiple electric power conversion is carried out by combining both the electric waveform for time synchronization which propagates on the power line which the power converter produced, and the electronic information for time synchronization which transmits the meaning which the electric waveform has It is characterized by time synchronization between devices, and time synchronization can be achieved by the following procedure.

  For example, a unique voltage waveform, current waveform, active power waveform, reactive power waveform, change in magnitude, change in phase, change in phase vector, change in space vector trajectory, and Inform the power converter that is synchronized in advance by another information route that the combined start / end warning signal and start / stop signal (collectively referred to as the electrical waveform profile) are sent to the power circuit. deep.

  The power converter that has received the information performs detection circuit configuration and software settings so that these electrical waveform profiles can be quickly detected as time-synchronized electrical waveforms, thereby preparing to synchronize the power conversion.

  When the electrical waveform profile of the warning signal transmitted to the power line in advance is detected around the scheduled time, the power converter starts preparations necessary for power conversion, and the voltage of the predetermined number of times is zeroed from the warning signal. Time synchronization of a plurality of power converters can be achieved by a method such as starting power conversion after a crossing cycle.

  Further, if a previous signal determined in advance by electronic information for time synchronization is detected for confirmation, an algorithm such as starting power conversion immediately after the detection confirmation can be provided.

  During power conversion, it is also possible to send out an electrical waveform profile determined in advance by electronic information for time synchronization, and to increase or decrease the magnitude of power conversion based on a predetermined output change rate.

  Even when power conversion is stopped, if the electric waveform profile defined in advance by electronic information for time synchronization is detected during power conversion, the size of power conversion is reduced at a constant rate of change after a certain zero crossing cycle, and a stop signal Can be stopped with detection.

  By transmitting in advance the procedure and electric waveform profile to be used as electronic information for time synchronization, the electric waveform profile can be simplified and the influence of noise can be reduced.

  In this way, by combining the electrical waveform profile that can be transmitted at the speed of light but with a small amount of information, and the electronic information for time synchronization that is rich in the amount of information to be sent by another route, a plurality of power converters at remote locations Can be synchronized. In the case of using power line carrier communication (PLC), since the electrical waveform and information pass through the same route, there is an advantage that the physical soundness of the route can also be confirmed.

  The invention according to claim 12 is characterized in that the electric waveform for time synchronization in the electric power system according to claim 11 is based on a current waveform.

The BTB type power converter rectifies alternating current with one power converter to create direct current, and then turns on and off the DC section voltage with the other power converter several thousand to several tens of thousands of times per second. A sinusoidal voltage is averaged by changing.
By synchronizing the frequency between this voltage and the power system connected across the series reactor and adding a slight phase difference, the target current can be sent or drawn.

  Since it is common to use a reactor or a smoothing capacitor in the output circuit of the power converter, the aforementioned voltage waveform, current waveform, active power waveform, reactive power waveform, changes in these magnitudes, When sending electrical waveform profiles such as phase vector changes, space vector trajectory changes, and combination start / end warning signals and start / stop signals to an electrical circuit, it is often necessary to devise the electrical circuit itself. . However, although the current waveform has a slow change speed due to the smoothing action of the reactor, it can be realized only by devising the signal to the digital signal processor of the power converter, and no special electric circuit devising is required. Therefore, it can be said that it is an economical method.

  By combining the method of detecting the phase shift by measuring the phase of the current based on the current waveform and the relative phase change of the space vector of the three-phase current, an electrical waveform profile with a relatively high amount of information can be obtained. be able to.

  According to a thirteenth aspect of the present invention, in the power system according to the eleventh aspect, the time synchronization electronic information is a power line carrier communication signal propagating on the power line.

  If a power line carrier system is used in which electronic information for time synchronization is transmitted on the same line as the power line through which the electric waveform for time synchronization is propagated, electronic information can be sent due to physical failure such as power line disconnection or grounding. If there is no response, there is no reply, so it is easy to find a problem with the power line.

  Not only the electronic information for time synchronization but also a power line carrier signal can be used as the electrical waveform for time synchronization and inserted at the timing of the voltage zero crossing to replace the electrical waveform profile for time synchronization.

  In the present embodiment, an embodiment of the invention according to claims 14 and 15 will be described.

  FIG. 20 is an example of a transaction book describing power transactions. Among these, an actual transaction is characterized in that a power loss associated with power conversion or power transmission occurs, so that a column for recording it is provided. This transaction book can also describe virtual transactions. In the case of a virtual transaction, a feature is that a description is made on both the input side and the output side, and a record such as a bond, a bill, or a certificate is used instead of cash income / expenditure.

  By using such a recording method, every user or business operator records power transactions through transaction books such as bank passbooks or journals such as double-entry bookkeeping, and distinguishes them from other power transactions. Will be able to.

This record is managed as electric power having various information such as transaction date / time, transaction volume, power generation energy source, power generation company, storage company, price, power loss, CO ₂ value, RPS value, and green power value. As a result, the information and the power are fused, and the power can be identified.

  This record is certified, traded and settled by a third party public authority. This third party role is like a bank in finance.

FIG. 21 is an example in which the change in the electric energy is disassembled into power interchangeable parts in the minimum unit.
There are three types of parts: an output only part, an input only part, and a part with input / output and a loss (referred to as an interchangeable part).

  In FIG. 21, the output from the power system 1 is represented by output parts, the loss at the converter is represented by interchangeable parts, the loss at the transmission line is represented by interchangeable parts, and the input to the power system 2 is input. Expressed in parts.

  Because of these parts notations, power interchange on a certain power interchange route is represented by the sum of simple parts. Therefore, the loss sharing in the case where a plurality of power interchanges can be easily separated into parts.

  In the present embodiment, an embodiment of the invention according to claims 16 and 17 will be described.

  First, the program for controlling the entire system of the multi-terminal type power converter recognizes the driver software for the input / output terminal, power converter circuit, control circuit, communication circuit, measurement circuit, protection circuit, recording circuit, and more detailed circuit, Even different hardware can function as a circuit of a multi-terminal power converter.

  In addition, since it is necessary to control a plurality of multi-terminal power converters in coordination with each other, the program of the present invention can be applied from a hardware aspect such as a chain blackout prevention to a software aspect such as an electric power transaction. It has a basic operating system that handles a wide range of content.

  Furthermore, by having a common basic operating system, the entire system can be controlled with the same concept, and software upgrades and bug fixes are made to all devices via an external communication line. , Can be processed remotely from a remote.

  As a result, a base on which a minimum operation protocol can be centrally managed is created.

  A basic operating system for a multi-terminal power converter is developed as a common operating system for all devices.

  First, this is common software for a “power system” in which a large number of multi-terminal power converters operate in a coordinated manner.

  In addition, it is possible to provide a program that solves problems in terms of economy and convenience by appropriately performing remote version upgrades.

  Furthermore, the watt-hour meter calibration and the abnormality detection procedure, which are the basis of power trading, become the basic algorithm of the basic operating system.

  In addition, the power loss minimization algorithm is the foundation of the basic operating system.

DESCRIPTION OF SYMBOLS 1 Multi-terminal type power converter 3 Power system 4 Power equipment single system 5 Core power system 6 Power bus 7 Interconnection line 8 Breaker 9 Disconnector 10 Bidirectional power converter 11 Transformer with power line carrying bypass 12 Power equipment control Terminal device 13 Power line carrier communication terminal 14 IP address 15 BTB type power converter 16 Voltage / current / power / power meter 17 Capacitor 18 Common DC bus 19 Reactor 20 Power system node 21 Power system link 21 Power transmission line 61 Power generation device 62 Power Storage Device 101 Operational State Bidirectional Power Converter 102 Stopped State Bidirectional Power Converter 161 Power Transaction Recording Device 201 A Input / Output Terminal 202 B Input / Output Terminal 203 Common DC Bus

The invention according to claim 1 is made to solve this problem, and includes three or more self-excited power converters that perform bidirectional power conversion, and one terminal of the self-excited power converter. A common bus connected in parallel, a voltage / current measuring device for measuring the voltage / current of the other terminal of each self-excited power converter, a voltage measuring device for measuring the voltage of the common bus, and the voltage / current measurement Voltage, current, power, frequency, and phase based on the measured values measured by the voltage measuring device and the voltage measuring device, one of the self-excited power converters maintains the voltage of the common bus, and the other The self-excited power converter performs power control for sending or flowing arbitrary power to the connection destination to which the other terminal of the self-excited power converter is connected, and the power flowing into the common bus and the common bus Total with the power sent from The self-excited power converter is controlled in a coordinated manner so that the other self-excited power converter is connected to the other end of the self-excited power converter in an asynchronous manner. And a power control system for controlling.
The invention according to claim 2 is a multi-terminal power converter, wherein three or more self-excited power converters that perform bidirectional power conversion and one terminal of the self-excited power converter are connected in parallel. A common bus, a voltage / current measuring device for measuring the voltage / current of the other terminal of each self-excited power converter, a voltage measuring device for measuring the voltage of the common bus, and a power storage connected to the common bus Calculating a voltage, current, power, frequency, and phase based on the measured value measured by the apparatus, the voltage / current measuring instrument and the voltage measuring instrument, causing the power storage device to maintain the voltage of the common bus, and , Performing power control for sending or flowing arbitrary power to a connection destination where the other terminal of the self-excited power converter is connected to the self-excited power converter, and common with the power flowing into the common bus With power sent from the bus The power storage device and a plurality of the self-excited power converters are cooperatively controlled so that the sum becomes zero, and power is exchanged asynchronously between the connection destinations to which the other terminals of the self-excited power converters are connected. And a power control system for controlling the self-excited power converter.
The invention according to claim 3 is the multi-terminal power conversion device according to claim 2, wherein the power storage device includes a DC power converter, and is connected to the common bus via the DC power converter. It is characterized by that.
The invention according to claim 4 is the multi-terminal power converter according to any one of claims 1 to 3, wherein the power control system controls the self-excited power converter to synchronize the frequency with the connection destination. It is characterized by doing.
The invention according to claim 5 is the multi-terminal power conversion device according to any one of claims 1 to 4, wherein the power control system includes power for each self-excited power converter input to the power control system. Based on the control target value, the self-excited power converter is controlled so as to send or flow arbitrary power to the connection destination.
The invention according to claim 6 is the multi-terminal power conversion device according to any one of claims 1 to 5, wherein the power control system performs the self-excited power conversion so as to maintain the voltage or current of the connection destination. It is characterized by controlling the vessel.

  In the invention according to one embodiment, a plurality of power conversions are performed by combining both a time synchronization electric waveform propagating on a power line created by a power converter and a time synchronization electronic information transmitting the meaning of the electric waveform. It is characterized by time synchronization between devices, and time synchronization can be achieved by the following procedure.

  The invention according to an embodiment is characterized in that the electrical waveform for time synchronization in the power system is based on a current waveform.

  The invention according to one embodiment is characterized in that, in the power system, the electronic information for time synchronization is a power line carrier communication signal propagating on the power line.

Claims (1)

Three or more self-excited power converters that perform bidirectional power conversion;
A voltage / current measuring device for measuring the voltage / current passing through each of the self-excited power converters;
A common bus connecting in parallel one terminal of the self-excited power converter;
Calculate voltage, current, power, frequency, and phase based on the measured values measured by the voltage / current measuring device, one of the self-excited power converters maintains the voltage of the common bus, and the other The self-excited power converter maintains the voltage or current of the connection destination to which the other terminal of the self-excited power converter is connected, and the sum of the power flowing into the common bus and the power sent from the common bus is zero The self-excited power converter is controlled in a coordinated manner so that the other terminals of the self-excited power converter are connected asynchronously and power is exchanged asynchronously. And a power control system for controlling the power.