CN106253345B

CN106253345B - A kind of electric power networks and its control method, device and system

Info

Publication number: CN106253345B
Application number: CN201610817474.4A
Authority: CN
Inventors: 舒鹏; 李龙彬; 朱江艳
Original assignee: ENN Science and Technology Development Co Ltd
Current assignee: ENN Science and Technology Development Co Ltd
Priority date: 2016-09-12
Filing date: 2016-09-12
Publication date: 2018-12-18
Anticipated expiration: 2036-09-12
Also published as: CN106253345A

Abstract

Embodiment of the invention discloses a kind of electric power networks and its control methods, device and system, it is related to power domain, to improve power plant utilization rate caused by the equilibrium of supply and demand in order to meet grid type microgrid in the prior art low problem or grid type the microgrid problem big to the demand of power grid.This method comprises: N number of microgrid, each microgrid includes: the first bus and the second bus connected by potential device, and the first bus is for connecting power plant and load；The second bus in each microgrid is connected by interconnection with the second bus of at least one other microgrid in N number of microgrid, and contact wiretap is provided on interconnection, and contact wiretap is used to control the microgrid connection being connected or disconnects；N number of microgrid is divided into M microgrid group, and every group of each microgrid is connected to by interconnection, and each microgrid group is connected to by points of common connection PCC with power grid power supply line, and the second bus of at least one microgrid is connect with energy storage device in N number of microgrid.

Description

Power network and control method, device and system thereof

Technical Field

The invention relates to the field of electric power, in particular to an electric power network and a control method, a device and a system thereof.

Background

The distributed energy can complement the traditional energy mode by the characteristics of high efficiency, cleanness, flexibility and the like. Micro-grids, also called micro-grids and micro-grids, are an important utilization mode of distributed energy, and are a system mainly composed of load and energy production equipment (mainly including distributed power generation equipment). The microgrid can be operated in a grid-connected mode with an external power grid, and can also be operated in an isolated mode.

Referring to fig. 1, a microgrid connected to a power grid, that is, a grid-connected microgrid, is characterized in that a power generation device and a load are provided therein, and the microgrid is connected to the power grid through a common connection point (also called a common connection point, which may be abbreviated as PCC: point of common connection).

The grid-connected microgrid mainly performs the balance of the production and consumption of electric energy in the interior below the PCC, usually works in a spontaneous self-use state, and insufficient part of electric power is supplemented by a power grid and does not transmit electric power back to the power grid. Because the microgrid back-transmission power may have intermittence and freedom, the problems of voltage fluctuation and the like of an area power grid can be influenced, the power grid usually limits the occurrence of the microgrid back-transmission current. Thus, the grid-connected microgrid may have the following two conditions in order to satisfy supply and demand balance: one of the situations is to limit the operation of the energy-producing equipment in the microgrid to a certain extent without sending back electric power to the power grid, for example, in a time period with good illumination conditions and low load, a part of photovoltaic power generation is abandoned, and the operation of equipment such as a gas generator is in a shutdown or non-rated output state, so that the operating efficiency is low, the annual available hours are reduced, and the like, which causes the problem of low utilization rate of the energy-producing equipment. Another situation is that a power grid is required to provide a large amount of power to the grid-connected microgrid, and especially when the load is too large, that is, the internal energy production of the microgrid is far less than the load, the demand of the grid-connected microgrid on the power grid is large.

Disclosure of Invention

Embodiments of the present invention provide a power network and a control method, an apparatus, and a system thereof, and provide a new power network and a control scheme for microgrid power in the power network in order to solve the problem in the prior art that the utilization rate of energy-producing devices is low or the demand of a grid is large due to the requirement for balance of supply and demand of a grid-connected microgrid.

In order to achieve the above purpose, the embodiment of the invention adopts the following technical scheme:

in a first aspect, an embodiment of the present invention provides an electrical power network, where the electrical power network includes: n microgrids, wherein N is more than or equal to 2;

each of the piconets comprises: the system comprises a first bus and a second bus which are connected through a transformation device, wherein the first bus is used for connecting a capacity device and a load; a second bus in each microgrid is connected with a second bus of at least one other microgrid in the N microgrids through a tie line, a tie line switch is arranged on the tie line, and the tie line switch is used for controlling the connected microgrids to be connected or disconnected;

the N micro-grids are divided into M micro-grid groups, each micro-grid in each group is communicated through the tie line, each micro-grid group is communicated with a power grid power supply circuit through a common connection point PCC, a second bus of at least one micro-grid in the N micro-grids is connected with an energy storage device, and M is larger than or equal to 1 and smaller than or equal to N.

Optionally, each piconet further includes: and the high-voltage side switch of the switch-in switching voltage transformation equipment is positioned between the first bus and the second bus.

The first aspect is the power network provided in the embodiments of the present invention, where the power network is a power network in which a plurality of micro-grids are jointly operated and then connected to a power grid. The micro-grids are connected through the tie lines, tie line switches are arranged on the tie lines, the tie line switches control connection and disconnection of the connected micro-grids, and energy exchange can be carried out between the connected micro-grids. In the power network provided by the embodiment of the invention, as long as two or more micro grids are communicated to form a micro grid group, energy exchange can be carried out among the micro grids (some micro grids supply surplus electric quantity to other micro grids in short of electric quantity). The microgrid in the power network provided by the embodiment of the invention can exchange energy, but the microgrid in the prior art cannot exchange energy. Meanwhile, energy storage equipment connected with a second bus of the microgrid is additionally arranged in the power network, so that the power network can be adjusted more flexibly. Therefore, compared with the prior art, the power network provided by the embodiment of the invention can solve the problem of low utilization rate of energy production equipment or the problem of large demand of the grid-connected microgrid on the grid caused by the requirement for balance of supply and demand of the grid-connected microgrid in the prior art.

In a second aspect, an embodiment of the present invention provides a method for controlling an electric power network, where the electric power network is the electric power network described in the first aspect;

the control method comprises the following steps: for each microgrid group including the energy storage device, a network scheduling device acquires a power operation interval allowed by any one microgrid in the microgrid group, wherein the power operation interval comprises: the maximum reverse power parameter and the maximum forward power parameter of the grid-connected point of the microgrid;

and sending the power operation interval allowed by the microgrid to a microgrid control device of the microgrid, so that the microgrid control device determines a power adjustment strategy of the energy storage equipment according to the real-time power P of the grid-connected point of the microgrid and the power operation interval allowed by the microgrid.

Optionally, the obtaining of the power operation interval allowed by each microgrid in the microgrid group includes: and acquiring the allowed power operation interval of the microgrid according to a preset time period.

Optionally, the obtaining of the power operation interval allowed by each microgrid in the microgrid group includes: receiving real-time operation parameters of the microgrid, which are sent by a microgrid control device of the microgrid, wherein the real-time operation parameters comprise:

the method comprises the steps that real-time power parameters of a grid-connected point of the microgrid and power improving capacity and power reducing capacity of the microgrid are obtained, and the real-time power parameters are used for obtaining real-time power values;

weighting and summing the real-time power value in the current time period of the grid-connected point of the microgrid and the real-time power value in the historical time period to obtain a power predicted value;

correcting the power predicted value according to the power improving capacity or the power reducing capacity of the microgrid to obtain a power corrected value;

and determining an interval containing the power correction value as an allowed power operation interval of the microgrid.

A third aspect and an embodiment of the present invention provide a network scheduling apparatus, configured to control an electric power network, where the electric power network is the electric power network described in the first aspect, and the apparatus includes, for each of the microgrid groups:

an obtaining unit, configured to obtain, by a network scheduling apparatus, a power operation interval allowed by any one of the micro grids in the micro grid group, where the power operation interval includes: the maximum reverse power parameter and the maximum forward power parameter of the grid-connected point of the microgrid;

and the transmitting unit is used for transmitting the power operation interval allowed by the microgrid to a microgrid control device of the microgrid, so that the microgrid control device can determine a power adjustment strategy of the energy storage equipment according to the real-time power P of the grid-connected point of the microgrid and the power operation interval allowed by the microgrid.

In a fourth aspect, an embodiment of the present invention provides a method for controlling an electric power network, where the electric power network is the electric power network described in the first aspect; the energy storage equipment is connected with a second bus of the first microgrid, and the energy storage equipment is controlled by a first microgrid control device of the first microgrid;

the control method comprises the following steps:

the first microgrid control device acquires a power adjustment strategy of the energy storage equipment;

and the first microgrid control device controls the power of the energy storage equipment according to the power adjustment strategy of the energy storage equipment.

Optionally, the obtaining, by the first microgrid control apparatus, a power adjustment policy of the energy storage device includes: the first piconet controlling device receives a power operation interval allowed by the first piconet and sent by a network scheduling device, and the power operation interval includes: a maximum reverse power parameter and a maximum forward power parameter of a grid-connected point of the first piconet; determining a power adjustment strategy of the energy storage device according to the real-time power P of the grid-connected point of the first microgrid and the power operation interval allowed by the first microgrid;

or,

and the first microgrid control device receives the power adjustment strategy of the energy storage equipment, which is sent by the second microgrid control device or the network scheduling device.

Optionally, the determining, according to the real-time power P of the grid-connected point of the first microgrid and the power operation interval allowed by the first microgrid, the power adjustment strategy of the energy storage device includes:

if the P is a negative value and the P is greater than the maximum reverse power, determining a power adjustment strategy of the energy storage device, wherein the power adjustment strategy comprises the following steps: increasing the discharge power of the energy storage device or decreasing the charge power of the energy storage device;

and/or the presence of a gas in the gas,

if P is a negative value and P is less than the maximum reverse power, determining a power adjustment strategy of the energy storage device, wherein the power adjustment strategy comprises: reducing the discharge power of the energy storage device or increasing the charge power of the energy storage device;

and/or the presence of a gas in the gas,

if P is a positive value and P is less than the maximum forward power, determining a power adjustment strategy of the energy storage device, wherein the power adjustment strategy comprises: reducing the discharge power of the energy storage device or increasing the charge power of the energy storage device;

and/or the presence of a gas in the gas,

if P is a positive value and P is greater than the maximum forward power, determining a power adjustment strategy of the energy storage device, wherein the power adjustment strategy comprises: increasing the discharge power of the energy storage device or decreasing the charge power of the energy storage device.

In a fifth aspect, an embodiment of the present invention provides a microgrid control apparatus, configured to control an electric power network, where the electric power network is the electric power network described in the first aspect, the energy storage device is connected to a second bus of a first microgrid, and the energy storage device is controlled by the first microgrid control apparatus of the first microgrid; the device includes:

the acquisition unit is used for acquiring the power adjustment strategy of the energy storage equipment by the first microgrid control device;

and the control unit is used for controlling the power of the energy storage equipment by the first microgrid control device according to the power adjustment strategy of the energy storage equipment.

A sixth aspect and an embodiment of the present invention provide a control system for an electric power network, where the electric power network is the electric power network in the first aspect, and the control system includes: the network scheduling device of the third aspect and the microgrid control device of the fifth aspect.

The second to sixth aspects are a method, an apparatus and a system for controlling a power network according to embodiments of the present invention. And aiming at each micro-grid group containing energy storage equipment, the network scheduling device acquires a power operation interval allowed by any one micro-grid in the micro-grid group, and transmits the power operation interval allowed by the micro-grid to the micro-grid control device of the micro-grid. The microgrid control device receives the power operation interval sent by the network scheduling device, and determines a power adjustment strategy of the energy storage equipment according to the real-time power P of the grid-connected point of the microgrid and the power operation interval allowed by the microgrid. The first microgrid control device acquires a power adjustment strategy of the energy storage equipment and controls the power of the energy storage equipment according to the power adjustment strategy of the energy storage equipment. Therefore, the micro-grid power is adjusted by adjusting the power of the energy storage device. The problem of low utilization rate of energy production equipment caused by the fact that supply and demand balance of the grid-connected micro-grid is met or the problem of large demand of the grid-connected micro-grid on the power grid in the prior art is further solved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic diagram of a single grid-connected microgrid structure provided in the prior art;

FIG. 2 is a diagram of an electrical topology of a power network according to an embodiment of the present invention;

fig. 3 is a second electrical topology diagram of the power network according to the embodiment of the invention;

FIG. 4 is a diagram of a control system for a power network according to an embodiment of the present invention;

FIG. 5 is a third electrical topology of a power network according to an embodiment of the present invention;

fig. 6 is a flowchart of a control method of an electric power network according to an embodiment of the present invention;

fig. 7 is a second flowchart of a control method of the power network according to the embodiment of the invention;

FIG. 8 is a schematic diagram of power division with a number axis according to an embodiment of the present invention;

fig. 9(a) is one of flowcharts illustrating a method for determining a power adjustment policy by the piconet controlling device according to the embodiment of the invention;

fig. 9(b) is a second flowchart illustrating the determining of the power adjustment strategy by the mcu according to the embodiment of the present invention;

fig. 10 is a third flowchart of a control method of a power network according to an embodiment of the present invention;

fig. 11 is one of block diagrams of a control device of an electric power network according to an embodiment of the present invention;

fig. 12 is a second block diagram of a control device of the power network according to the embodiment of the present invention;

fig. 13 is a block diagram of a control system of an electrical power network according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

For the convenience of clearly describing the technical solutions of the embodiments of the present invention, in the embodiments of the present invention, the words "first", "second", and the like are used to distinguish the same items or similar items with basically the same functions and actions, and those skilled in the art can understand that the words "first", "second", and the like do not limit the quantity and execution order.

In addition, the terms "system" and "network" in embodiments of the present invention are often used interchangeably in embodiments of the present invention. The term "and/or" in the embodiment of the present invention is only one kind of association relationship describing an associated object, and indicates that three relationships may exist, for example, a and/or B may indicate: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" in the embodiment of the present invention generally indicates that the preceding and following related objects are in an "or" relationship. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

Example one

In the prior art, a single grid-connected microgrid operates independently, but due to the limitation that PCC power is not allowed to flow from a primary microgrid to a power grid, the power generation amount of power generation equipment of the microgrid is limited, or a large amount of energy storage equipment is required to be added. This practice may deviate from the actual requirements of the microgrid or may raise both the investment costs and the operating costs of the microgrid. Therefore, in order to solve the above problems, the embodiments of the present invention provide a novel power network. Referring to fig. 2, in the new power network, in the embodiment of the present invention, a plurality of micro grids are connected by a tie line to form a combined grid-connected micro grid, and when a plurality of micro grids operate in a combined manner, due to different laws of energy generation and utilization among the micro grids, a network complementary effect may be formed. It should be noted that, in the following description of the embodiments, a primary piconet refers to a single piconet, and a secondary piconet refers to a grid-connected piconet formed by connecting a plurality of primary piconets.

Firstly, the power network provided by the embodiment of the invention is introduced, and the power network consists of N micro-grids, wherein N is more than or equal to 2. In this embodiment, taking N ═ 3 as an example, referring to fig. 2, the power network is a two-stage microgrid formed by combining 3 primary microgrids, i.e., a microgrid 1, a microgrid 2, and a microgrid 3.

Specifically, each piconet includes, for example, the # 1 piconet: a first bus (bus)12 and a second bus 13 connected by a voltage transformation device 11. The first bus bar 12 is connected to the low voltage side of the transformation device 11, illustratively a 0.4kV low voltage bus bar, and the second bus bar 13 is connected to the high voltage side of the transformation device 11, illustratively a 10kV high voltage bus bar. Wherein the first busbar 12 is used for connecting energy production equipment and loads. The energy production equipment in the microgrid mainly comprises distributed power generation equipment and first energy storage equipment. It should be noted that: for convenience of distinction, in the embodiment of the present invention, the energy storage device connected to the first bus of the microgrid is referred to as a first energy storage device; the energy storage device connected to the second bus of the microgrid is referred to as a second energy storage device. The distributed power generation equipment can be divided into cogeneration power generation, internal combustion engine set power generation, gas turbine power generation, small hydroelectric power generation, wind power generation, solar photovoltaic power generation, fuel cells and the like according to different use technologies; the first energy storage equipment mainly comprises a low-power energy storage battery, and the power is generally lower than 400 kW; the load mainly refers to a power utilization line. The power generation device and the first energy storage device may be different devices, and the power generation device and the first energy storage device are connected to enable generated electric energy to be stored in the first energy storage device; both may also be present as an integrated device, in which case the first energy storage device may be a component of the power generation device. For convenience of description and understanding, the photovoltaic power generation device, the cogeneration device and the first energy storage device in the drawings of the embodiment of the invention represent energy production devices; the load is represented by an electrical line.

The second bus 13 in each microgrid is connected to the second bus 13 of at least one other microgrid out of the N microgrids via a tie line 14; that is, there is no primary piconet in the same secondary piconet that is not connected to any piconet via a tie. For example, referring to fig. 2, for piconet No. 1, piconet No. 1 is connected to piconet No. 2 via a link 14; for the microgrid 3, the microgrid 3 is connected with the microgrid 2 through a connecting line 14; for the microgrid 2, the microgrid 2 is connected with the microgrid 1 and the microgrid 3 through the connecting lines 14. The tie 14 is illustratively a 10kV high voltage cable. The tie line 14 is provided with a tie line switch, and the tie line switch is used for controlling connection or disconnection of the connected micro grids.

It should be noted that the distinction between "connected" and "connected" herein: "connected" means connected but not necessarily in communication, i.e., not necessarily in the flow of electrical current; "connected" means connected and open, with current flowing through. For example: the two micro-grids connected together mean that the two micro-grids are connected together by using a connecting line, but a switch on the connecting line can be in a closing state or an opening state; the two micro-grids which are communicated are connected together by a connecting line, and a switch on the connecting line is in a closing state.

Alternatively, the tie 14 may be common and shared by more than 3 piconets. Referring to fig. 3, all piconets are connected together by a common tie. The part of the tie line 14 connected to the second bus of each microgrid has a tie line switch for controlling the microgrid to be connected to or disconnected from other microgrids.

Preferably, the tie 14 is independent and is used by only two piconets. Referring to fig. 2, two sss connected to each other are connected by an independent tie, which means that the tie is used to connect only two sss, but not to other sss. Optionally, at least one end of the tie line 14 is provided with a tie line switch, it should be noted that, here, one end of the tie line is not an end point of the tie line, but is on a portion of the tie line close to the second bus 13 of the microgrid, and at this time, the tie line switch belongs to the microgrid where the second bus 13 close to the tie line is located, and the opening and closing of the tie line switch can be controlled by the microgrid control device of the microgrid; which end is provided with a tie switch does not represent its physical location but indicates to which microgrid the tie switch belongs. For example, the tie switch 17 is provided on a portion of the tie 14 adjacent to the second bus 13 of the No. 2 microgrid, and the tie switch 17 belongs to the No. 2 microgrid, and the microgrid control device of the No. 2 microgrid can control opening and closing of the tie switch 17. The connection or disconnection between the two micro grids can be flexibly controlled by the aid of the connecting line switch arranged at least one end of the connecting line, and the connection or disconnection between the two micro grids and other micro grids is not affected.

Preferably, the two ends of the tie line are respectively provided with a tie line switch. For example, the tie switch 17 and the tie switch 18 on the tie 14, in which case the opening and closing of the tie switch 17 may be controlled by the microgrid control device of the No. 2 microgrid, and the opening and closing of the tie switch 18 may be controlled by the microgrid control device of the No. 1 microgrid. Therefore, any one of the two connected micro-grids can be controlled to be disconnected by controlling the opening or closing of the tie line switch, so that the control is more flexible.

N micro-grids in the power network are divided into M micro-grid groups, M is more than or equal to 1 and less than or equal to N, all micro-grids in each group are communicated through a connecting line, and energy can be exchanged among different micro-grids in the micro-grid groups. The grouping is not constant, and the division of the microgrid group changes with the change of the connection state between the microgrids. In this embodiment, a combination of a plurality of (at least two) primary piconets in the two-level piconets, which are connected to each other, is referred to as a piconet set, and a primary piconet in the two-level piconets, which is not connected to any other piconet, may also be referred to as a piconet set.

In order to make each microgrid group be of a grid-connected type, each microgrid group is communicated with a power supply line of a power grid through a common connection point PCC. Preferably, this embodiment requires that at least one microgrid in each microgrid group is connected to the grid power supply lines via an access switch 15 at the point of common connection PCC. And only one access switch in each group is communicated with the power supply line of the power grid so as to control one microgrid group.

The two-level microgrid provided by the embodiment of the invention can be provided with one or more microgrid sets, and different microgrids in the same microgrid set are communicated by virtue of the connecting lines, so that energy exchange can be carried out through the connecting lines, namely surplus electricity of some one-level microgrids can be transmitted back to the two-level microgrid and supplied to other one-level microgrids for use. At least one microgrid in the microgrid group is connected to power supply circuits through an access switch, namely more than one microgrid group can be arranged in one microgrid group, but different power supply circuits are not necessarily completely identical in frequency phase and cannot simultaneously supply power to the same microgrid group, so that only one power supply circuit is connected in each microgrid group to supply power to the microgrid, and other power supply circuits of the microgrid group are disconnected and are in a standby state.

For example, in the two-stage microgrid shown in fig. 2, the tie line switches of the 1 st, 2 nd and 3 rd microgrids are all switched on, so that a microgrid group is formed. The microgrid group is connected with two power grid power supply lines, namely, the No. 1 microgrid is connected with the power grid power supply lines through an access switch 15, and the No. 3 microgrid is connected with the power grid power supply lines through the access switch 15. The power grid power supply circuit connected with the No. 1 micro-grid is a main power supply circuit of the micro-grid group, and the power grid power supply circuit connected with the No. 3 micro-grid is a standby power supply circuit of the micro-grid group. If a plurality of power supply lines exist in one microgrid group, preferably, a power supply line meeting the condition that the power demand of the whole microgrid group on the power supply line cannot exceed the load threshold value on the power supply line is selected as a main power supply line by calculating the power demand of the whole microgrid group on the power supply line. And if a plurality of power grid power supply circuits meet the condition, selecting any one of the power grid power supply circuits meeting the condition as a main power supply circuit. If one micro-grid group has a plurality of power grid power supply circuits, when one power grid power supply circuit fails or cannot meet the conditions, or the long-term supply and demand relationship of each micro-grid changes so that the network topology needs to be changed, the standby power supply circuit can become the main power supply circuit, so that the control is more flexible. Moreover, only one PCC access switch of each microgrid group is communicated with the power grid, so that the management difficulty of the power grid is reduced; the microgrid group illustrated in this embodiment is connected to a main power supply line, that is, the access switch 15 of the No. 1 microgrid is switched on, and the access switch 15 of the No. 3 microgrid is switched off.

Based on the connection relationship assumed by each microgrid and the power grid, according to the arrow direction of each microgrid, the surplus power is generated in the No. 2 microgrid, and the power of the No. 1 microgrid and the No. 3 microgrid is in short supply, the surplus power is transmitted back to the second-level microgrid by the No. 2 microgrid and is supplied to the No. 1 microgrid and the No. 3 microgrid for use, and if the power of the No. 1 microgrid and the No. 3 microgrid is still insufficient, the surplus power is provided by the power grid (namely, a main power supply line). Therefore, the generated energy of the distributed generation equipment of the No. 2 micro-grid does not need to be reduced, and the utilization rate of the distributed generation equipment is improved; meanwhile, the 3 first-level micro-grids jointly run, so that the overall demand on the power grid is reduced.

Preferably, each microgrid in the power network provided in the embodiment of the present invention further includes: and the high-voltage side switch of the transformation equipment is positioned between the first bus and the second bus. In the embodiment of the present invention, the voltage transformation device may be a transformer, and the high-voltage side switch of the voltage transformation device may be a high-voltage side switch 16 of the voltage transformation device, which is located between the first bus 12 and the second bus 13 in the No. 1 microgrid shown in fig. 2, when there is only one voltage transformation device between the first bus and the second bus; the high-voltage side switch of the transformer device may be a common upper-stage main switch for connecting a plurality of transformer devices between the first bus and the second bus when a plurality of transformer devices are provided between the first bus and the second bus. The function of the high-voltage side switch of the voltage transformation equipment is that when one of the multiple micro-grids of the micro-grid group has a serious fault, such as a line short circuit or the loss of control of the power generation equipment, and the other micro-grids are affected by the serious fault, the micro-grid can be isolated by only disconnecting the high-voltage side switch of the voltage transformation equipment of the micro-grid, and the states of other switches are not required to be changed, so that the other micro-grids are not affected. Meanwhile, compared with the method that all tie line switches of the microgrid are switched off, the method can further influence the states of access switches at certain PCC, the control is simpler, and the damage to the device is smaller.

Secondly, for the above power network, the present embodiment further provides a control system of the power network, where the control system includes: the system comprises N micro-grid control devices, a network scheduling device connected with the N micro-grid control devices, a network operation device connected with the network scheduling device, and an equipment level controller connected with the micro-grid control devices, wherein N is more than or equal to 2. The device-level controller comprises a controller of the first energy storage device, a controller of the second energy storage device, a controller of the power generation device, a load controller and the like.

In the embodiment, taking an electric power network composed of three micro-grids as an example, referring to fig. 4, a control system of the electric power network includes 3 micro-grid control devices, that is, a No. 1 micro-grid control device, a No. 2 micro-grid control device, and a No. 3 micro-grid control device; and the network scheduling device is connected with the 3 microgrid control devices. Each micro-grid control device completes internal management of the controlled micro-grid by controlling each equipment-level controller and is controlled by a network scheduling device of the second-level micro-grid. The network scheduling device is used as a management system of the second-level microgrid and is used for completing control of an interface (an access switch communicated with the power grid) with the power grid and scheduling instructions for each microgrid. For example: the overall scheduling among the micro-grids and the control of which power grid power supply line the micro-grid group is communicated with are completed by a network scheduling device; the control of each microgrid energy production device and load can be completed by each microgrid control device.

Referring to fig. 4, in the embodiment of the present invention, a network operating apparatus is connected to a network scheduling apparatus. And the network scheduling device sends the operation data of the secondary microgrid to the network operation device to carry out network operation management. The network operation device is used for executing at least one of user management, metering and transaction payment management, equipment asset management and operation decision aiming at the N micro-networks. The bidirectional exchange of energy between micro-grids occurs continuously, and the micro-grids usually belong to different owners or settlement units, so that the real-time exchange amount of energy needs to be counted to generate bills. The network operation device continuously updates the statistical data according to the data sent by the network scheduling device.

The embodiment of the invention provides a power network, wherein a plurality of primary micro-grids are connected through a connecting line to form a secondary micro-grid, and the primary micro-grids can provide standby power consumption mutually due to different laws of productivity and load. That is to say, the first-level microgrid can be allowed to transmit power back in the second-level microgrid, so that the bottleneck of supply and demand interaction of a single grid-connected microgrid can be overcome, the utilization level of capacity equipment in the microgrid is greatly improved, and particularly the utilization level of distributed power generation equipment such as photovoltaic power generation and wind power generation is improved. However, the larger the scale of the formation of the secondary microgrid is, the higher the difficulty of network operation control is, and the problem mainly lies in the intermittent coexistence of the freedom of the demand end and the power generation end of the primary microgrid.

Freedom of the demand end: the demands of users in the primary micro-network on various energy sources are mostly random and have no uniform rule. That is to say, the electricity utilization law and the like in the first-level microgrid are completely according to respective needs of users, are not connected with each other, and cannot be managed.

The intermittence of the power generation end is as follows: taking photovoltaic power generation as an example, the photovoltaic power generation equipment works intermittently according to illumination change, and the shortest change frequency can reach 2-3 seconds.

In the extreme case of the intermittence coexistence of the freedom of the demand end of the primary microgrid and the power generation end, tidal current problems in the secondary microgrid can be caused, such as overload of part of branch lines, over-high or under-low voltage of high-voltage electrical nodes, and the like. Through the mutual cooperation of the overall scheduling of each primary micro-grid by the network scheduling device of the secondary micro-grid and the control of the capacity equipment and the load by each primary micro-grid control device, the tidal current problem in the secondary micro-grid can be solved within a certain time (generally 15 minutes). However, due to the limitation of special conditions of some first-level micro-grids, it is difficult to coordinate with the overall control of the second-level micro-grid (the overall scheduling of each first-level micro-grid by the network scheduling device of the second-level micro-grid), and there is a control limitation. The special condition restriction of the first-level piconet may be, for example: 1) the limitations of a part of power generation equipment in a primary microgrid are that the regulation function cannot be assumed, such as photovoltaic and wind power generation, basically depends on intermittent natural illumination and wind power. 2) The first-level micro-grid contains gas combined heat and power supply equipment, so that power adjustment cannot be performed in order to guarantee heat supply, or the operation efficiency of the gas combined heat and power supply equipment is seriously influenced and even the gas combined heat and power supply equipment is stopped if the power adjustment is performed.

In summary, the microgrid control device needs to ensure balance between the energy production equipment and the load supply and demand in the first-level microgrid, which may cause a delay in responding to a command of the network scheduling device, or may cause an inability to respond to a command of the network scheduling device due to uncontrollable distributed power generation equipment in the first-level microgrid, and the overall result is that the coordination control between the network scheduling device and the microgrid control device is not flexible enough, and is not suitable for system control in a short time period (1-15-minute control gap).

Therefore, in an embodiment of the invention, the second bus of at least one of the N piconets is connected to the energy storage device. The second energy storage device is preferably a high-power energy storage device, is connected to the high-voltage side of the first-level microgrid voltage transformation device, has power of 500kW to several megawatts, and is generally a high-power energy storage battery. In the secondary microgrid, the second energy storage device and all the microgrids are on the same electrical node, and the current absorbed or discharged by the second energy storage device can directly reach each microgrid, that is, the second energy storage device can serve the whole secondary microgrid. In a two-level microgrid, there may be a plurality of second energy storage devices, but the number of the second energy storage devices is preferably less than that of the one-level microgrid, and the smaller the number of the second energy storage devices is, the better the requirement of the whole two-level microgrid can be met. Because the second energy storage devices are installed on the high-voltage side of the microgrid, if the number of the second energy storage devices is too large, the stability of the voltage of the whole microgrid can be influenced. The power of the energy storage device can be charging power or discharging power, and the charging and discharging rated powers of the energy storage device are equal.

In one secondary microgrid, the number of the second energy storage devices and the second bus connected to which primary microgrid are set according to the needs of the number of the primary microgrids, the types and scales of the distributed power generation devices in the primary microgrid, and the like.

For example, referring to fig. 2, three sss, i.e., No. 1 ss, No. 2 ss, and No. 3 ss, are connected by a link line to form a two-stage ss. Compared with a No. 1 micro-grid and a No. 3 micro-grid, the No. 2 micro-grid takes photovoltaic power generation as main distributed power generation equipment, and the installed scale of the photovoltaic power generation equipment is large. Under the conditions of good illumination condition and low load, the No. 2 microgrid can transmit power back to the second-level microgrid, but due to the intermittence of illumination or the irregularity of load, the power transmitted back from the No. 2 microgrid to the second-level microgrid has intermittence; no. 2 micro-grid also has gas triple-supply equipment, and the gas triple-supply equipment is known to maintain certain working power (for example, 60% to cold supply) in order to guarantee heating/cooling tasks

Between 100%) and its regulation speed is slow. Therefore, a second energy storage device 19 is connected to the second bus of the No. 2 microgrid.

Specifically, the second energy storage device 19 is connected at a voltage level of 10kV, and the power can reach 500kW to several megawatts. When the No. 2 microgrid has surplus electric quantity, the electric quantity is transmitted back to the second-level microgrid, and the second energy storage device can absorb the surplus electric quantity. When the load of the No. 2 microgrid is large and the electric quantity is in shortage, the second energy storage equipment can release the electric quantity to supply to the No. 2 microgrid for use. Similarly, because the second energy storage device and the 3 microgrids are located on the same electrical node, the electric power sent back by the No. 1 microgrid and the No. 3 microgrid can be absorbed by the second energy storage device, and the electric power released by the second energy storage device can be supplied to the No. 1 microgrid and the No. 3 microgrid for use. That is, the second energy storage device serves the entire two-level microgrid.

Therefore, the adjustable second energy storage device is added on the 10kV high-voltage bus of the first-level microgrid, so that the matching delay of the first-level microgrid and the second-level microgrid is made up, the control period (the control interval is controlled within 1-15 minutes) is shortened, and the control flexibility of the power network is improved.

Again, the embodiments of the present invention need to control (regulate) the power in the power network, and in order to clarify the meaning of the direction and sign of the electrical energy (current/power) in the present application, the following provisions are made in the present embodiment:

the current/power collection point of the power network provided by the embodiment of the invention is mainly a grid-connected point (which can be PCC) where the secondary microgrid is merged into a power grid and a grid-connected point (which can be a switch position on a high-voltage side of a voltage transformation device) where the primary microgrid is merged into the secondary microgrid.

Positive and negative of current/power: generally, the current inflow bus is negative and the current outflow bus is positive. Then the power is the same, with the power in bus being negative and the power out bus being positive. It should be noted that: in the drawings of the embodiments of the present invention, the directions of the arrows represent the flow of current/power. In the two-stage piconet shown in fig. 5, 3 piconets, i.e., the piconet No. 1, the piconet No. 2, and the piconet No. 3, are connected to form a piconet group. The current/power flow in the grid and in the 3 microgrids is shown by the arrow direction in the figure. Then, it can be known that the current/power acquired by the PCC in the No. 1 microgrid is negative, and when the direction is opposite to the current direction, the current/power is positive; and the current/power collected at the No. 1 microgrid grid-connected point is positive, and the current/power collected at the No. 2 microgrid grid-connected point is negative.

Positive direction and negative direction of current/power: the positive direction of the current/power of the PCC refers to a direction of injecting electric energy from the power grid line to the secondary microgrid, that is, the direction of the current/power at the PCC of the No. 1 microgrid in fig. 5 is a positive direction, and the direction opposite to the current direction in fig. 5 is a reverse direction of the current/power of the PCC. Similarly, the positive direction of the current/power of the grid-connected point refers to the direction in which the secondary microgrid injects electric energy into the primary microgrid, i.e., the direction of the current/power at the grid-connected point of the No. 1 microgrid in fig. 5 is the positive direction; the current direction of current/power at the No. 2 microgrid grid-connected point is the opposite direction.

Therefore, the positions of the secondary microgrid acquisition Points (PCC) and the primary microgrid acquisition points (microgrid grid-connected points) are different, so that the direction is the same positive direction, and the current/power is opposite in positive and negative. For example: in fig. 5, the current/power direction of the PCC of microgrid No. 1 is positive, but the current/power is negative; the current/power direction of the No. 1 microgrid grid-connected point is also positive, but the current/power is positive. It should be noted that: for convenience of description, the forward direction is simply referred to as the forward direction, the reverse direction is simply referred to as the reverse direction, and the current/power reverse direction, the reverse current/power, the reverse power, and the like mean that the current/power is the reverse direction.

Example two

An embodiment of the present invention provides a control method for the power network, and as shown in fig. 6, an execution main body of each step is a network scheduling device, and the specific steps include:

s601 (optional) the network scheduling device receives the real-time operation parameters of the microgrid transmitted by the microgrid control device of the microgrid.

The real-time operation parameters of the microgrid comprise: the real-time power parameters of the grid-connected point of the microgrid, and the power increasing capability and the power reducing capability of the microgrid. The real-time power parameters of the grid-connected point of the microgrid may include one or more of active power, reactive power, power factor, voltage and current of the grid-connected point of the microgrid. The real-time power parameter is used for calculating to obtain a real-time power value, and the real-time power value is an active power value of the microgrid grid-connected point. For example, if the real-time power parameters are reactive power and power factor, the real-time power parameters can be obtained by a formula of active power/(1-power factor); if the real-time power parameters are power factors, voltages and currents, the real-time power parameters can be obtained by a formula of active power, namely voltage, current and power factors; other existing formulas for calculating the active power are also possible, and are not described in detail here.

Since the positive and negative directions and the positive and negative signs of the power/current are specified in the embodiment, when the active power, the reactive power and the current of the grid-connected point of the primary microgrid are positive values, the positive direction of the power/current is represented, and at the moment, the power/current flows from the secondary microgrid to the primary microgrid; when the power/current of the grid-connected point of the microgrid is a negative value, the power/current is in a reverse direction, and the power/current flows from the primary microgrid to the secondary microgrid. The power of the PCC cannot be usually reversed, so the real-time power parameter of the PCC of the microgrid group is always positive, and is represented by a negative value because the real-time power parameter flows into the microgrid bus at the moment.

For example, referring to fig. 5, a microgrid 1, a microgrid 2, and a microgrid 3 are connected by a tie to form a two-stage microgrid, and now a tie switch between the microgrid 1 and the microgrid 2 is switched on, and a tie switch between the microgrid 2 and the microgrid 3 is switched on, so that the three microgrids are connected to form a microgrid group for joint operation. The current/power direction of the No. 1 and No. 3 microgrid grid-connected points is forward, and the current/power direction of the No. 2 microgrid grid-connected points is reverse, so that the reverse current/power flowing out of the No. 2 microgrid can be absorbed by the No. 1 microgrid and/or the No. 3 microgrid. The reverse power of some piconets in the piconet group is absorbed by other piconets, and which piconet in the piconet group has the reverse power or several piconets have the reverse power are not constrained. That is, when the current/power of the piconet No. 2 and the piconet No. 3 in the piconet group shown in fig. 5 are reversed, and the current/power of the piconet No. 1 is still forward, the reverse current/power of the piconet No. 2 and the piconet No. 3 can also be absorbed by the piconet No. 1. In this embodiment, it is preferable that any one of the microgrid sets does not return electric energy to the power grid, so that the sum of the reverse currents/powers of the microgrid grid-connected points in any one of the microgrid sets is not greater than the sum of the forward currents/powers, of course, the sum of the reverse currents/powers of the microgrid grid-connected points in one of the microgrid sets may be 0, and at this time, the currents/powers of the microgrid grid-connected points in this microgrid set are all in the forward direction.

Preferably, each microgrid control device sends the real-time operation parameters of the microgrid controlled by the microgrid control device to the network scheduling device according to a preset time period, wherein one microgrid of one microgrid group is communicated with the power grid line through a PCC, so that the microgrid control device of the microgrid can also obtain the real-time power parameters of the PCC of the microgrid and send the real-time power parameters of the PCC to the network scheduling device.

At this time, the No. 1 microgrid control device can send the real-time operation parameters of the No. 1 microgrid and the real-time power parameters of the PCC to the network scheduling device; the No. 2 microgrid control device can send the real-time operation parameters of the No. 2 microgrid to the network scheduling device; the No. 3 microgrid control device can send the real-time operation parameters of the No. 3 microgrid to the network scheduling device.

Correspondingly, the network scheduling device may receive the real-time power parameter of the PCC of each piconet set and the real-time operation parameter of each piconet in the piconet set according to a preset time period (i.e., a period sent by each piconet control device).

For example, the preset period may be 15 to 60 minutes, and for example, the preset period may be received by the network scheduling device every 15 minutes.

And S602, aiming at each microgrid group containing second energy storage equipment, acquiring a power operation interval allowed by any one microgrid in the microgrid group by using a network scheduling device.

It should be noted that: for convenience of distinction, in the embodiment of the present invention, the energy storage device connected to the first bus of the microgrid is referred to as a first energy storage device; the energy storage device connected to the second bus of the microgrid is referred to as a second energy storage device.

The allowed power operation interval of the microgrid comprises: and the maximum reverse power parameter and the maximum forward power parameter of the grid-connected point of the microgrid. Since the positive direction and the positive and negative signs of the power/current are specified in this embodiment, the reverse power parameter of the grid-connected point is always a negative value, the forward power parameter is always a positive value, and the magnitude of the reverse power parameter is based on the magnitude of the absolute value of the reverse power parameter, that is, the larger the absolute value of the reverse power parameter is, the larger the absolute value of the reverse power parameter is, wherein the maximum reverse power parameter is the maximum value of the reverse power parameters allowed by the grid-connected point of the piconet.

This step is preferably: and acquiring the allowed power operation interval of the microgrid according to a preset time period. For example, the preset time period may be the same as the period of step S601, i.e., the step is performed immediately after step S601 is performed. Of course, if step S601 is not executed, the period here may be set as needed, and may be 15 to 60 minutes, for example, every 15 minutes. Optionally, for obtaining the power operation interval allowed by the microgrid, a corresponding power operation interval may be set for each microgrid according to actual experience. For example: the power operation interval of each microgrid can be input by a worker through an interactive interface of the network scheduling device; further, the adjustment may be performed once every certain period of time (re-input). Another example is: a plurality of power operation intervals may be pre-stored in the network scheduling apparatus, so that one of the pre-stored power operation intervals is selected for each microgrid at intervals, where the selection may be an optional one, or may be selected from the pre-stored power operation intervals according to a preset rule.

Preferably, the network scheduling device of the second-level microgrid may perform short-term power prediction and calculate a power operation interval allowed by the microgrid according to the real-time operation parameters of the microgrid received in step S601.

Specifically, the real-time power value in the current time period of the grid-connected point of the microgrid and the real-time power value in the historical time period are weighted and summed to obtain the power prediction value. The real-time power value in the current time period may be an average of the real-time power values in the current time period, and the time period may be 15-60 minutes, for example 15 minutes. The weight of the weighted sum may be set according to specific situations, and is not limited herein. The historical time period may be a previous time period of the current time period, or may be a time period corresponding to a certain day, or other reasonable historical time periods may be used, which is not described herein again. Correcting the power predicted value according to the power improving capacity or the power reducing capacity of the microgrid to obtain a power corrected value; and determining an interval containing the power correction value as an allowed power operation interval of the microgrid. It should be noted that: the final power operation interval may be an interval with the power correction value as a boundary, an interval with the power correction value multiplied by a correction coefficient or added or subtracted by a correction coefficient as a boundary, or other reasonable cases.

For example, the power predicted value is obtained by multiplying the average of the real-time power of the current 15 minutes by the weight 0.6 and multiplying the average of the real-time power of the period corresponding to the current day (for example, yesterday) by the weight 0.4. And correcting the difference between the power predicted value and the power lifting capacity again to obtain the maximum reverse power as the left boundary of the power operation interval. The second correction may be performed by taking an absolute value of a difference between the predicted power value and the power boost capability, then multiplying the absolute value by a correction coefficient or adding or subtracting a correction coefficient, and then taking a negative value. And the maximum forward power obtained by correcting the sum of the predicted power value and the power reduction capability again serves as the right boundary of the power operation interval as a power correction value. The correction may be performed again by taking the absolute value of the sum of the predicted power value and the power reduction capability, multiplying the absolute value by a correction coefficient, or adding or subtracting a correction coefficient, and then taking a positive value.

And S603, transmitting the power operation interval allowed by the microgrid to the microgrid control device of the microgrid.

Specifically, the network scheduling device of the second-level microgrid transmits the power operation interval to the microgrid control device of the first-level microgrid through a communication line between the network scheduling device and the microgrid control device. For example, taking fig. 5 as an example, the network scheduling device may send the power operation interval allowed by the No. 1 microgrid to the No. 1 microgrid control device, send the power operation interval allowed by the No. 2 microgrid to the No. 2 microgrid control device, and send the power operation interval allowed by the No. 3 microgrid to the No. 3 microgrid control device.

After the microgrid control device receives the control command of the power operation interval sent by the network scheduling device, the microgrid control device of the microgrid determines a power adjustment strategy of the second energy storage device according to the real-time power P of the grid-connected point of the microgrid and the power operation interval allowed by the microgrid. Because the period of the command issued by the network scheduling device may be 15 minutes to 60 minutes, the microgrid control device may always perform power adjustment by using the power operation interval in the control command received this time before issuing the command next time.

The embodiment of the invention provides a control method of a power network, which aims at the power network which jointly operates a plurality of micro-grids and is then connected with a power grid in a grid-connected mode. And the network scheduling device acquires the power operation interval of the microgrid controlled by the network scheduling device and sends the power operation interval to the microgrid control device. The power control of the power network provided by the embodiment of the invention is realized.

EXAMPLE III

The present embodiment provides a method for controlling a power network, wherein the power network is the same as the power network described above. The following are specific steps of a method for controlling a power network according to an embodiment of the present invention, and refer to fig. 7. The execution main body of each step is a first microgrid control device, the microgrid controlled by the first microgrid control device comprises second energy storage equipment, the second energy storage equipment is connected with a second bus of the first microgrid, and the second energy storage equipment is controlled by the first microgrid control device of the first microgrid.

S701 (optional), the first piconet controlling device sends the real-time operating parameter of the first piconet controlled by the first piconet controlling device to the network scheduling device.

In the embodiment of the present invention, the second microgrid control device may also send the real-time operation parameters of the second microgrid controlled by the second microgrid control device to the network scheduling device. The real-time operation parameters of the first piconet or the second piconet may refer to the real-time operation parameters of the piconet in the second embodiment, which are not described herein again.

For example, referring to fig. 5 as an example, it can be seen that ss 2 is a first ss, ss 1 and ss 3 are second sss. Therefore, at this time, the No. 2 microgrid control device may send the real-time operation parameters of the No. 2 microgrid to the network scheduling device, the No. 1 microgrid control device may send the real-time operation parameters of the No. 1 microgrid to the network scheduling device, and the No. 3 microgrid control device may send the real-time operation parameters of the No. 3 microgrid to the network scheduling device.

It should be noted that: in the following description of the embodiments, for simplicity, the first ss is described as the ss No. 2 in fig. 5, and the second ss is described as the ss No. 1.

Correspondingly, the network scheduling device may obtain the allowed power operation interval of the microgrid controlled by the microgrid control device according to the real-time operation parameters sent by the microgrid control device in the second step.

For example, if the real-time operation parameters of the microgrid are sent to the network scheduling device by the No. 2 microgrid (the first microgrid), the network scheduling device may obtain the power operation interval allowed by the No. 2 microgrid according to the steps in the second embodiment, and send the power operation interval to the No. 2 first microgrid. If the real-time operation parameters of the first microgrid are sent to the network scheduling device by the No. 1 microgrid (the second microgrid), the network scheduling device may obtain the power operation interval allowed by the No. 1 microgrid according to the steps of the second embodiment and send the power operation interval to the No. 1 microgrid.

S702 (optionally), the first piconet controlling device receives the allowed power operation interval of the first piconet transmitted by the network scheduling device.

In this embodiment of the present invention, the second piconet controlling device may also receive the allowed power operation interval of the second piconet transmitted by the network scheduling device.

The step may be specifically that the microgrid control device receives an allowable power operation interval once in a certain preset time period, for example, 15 to 60 minutes.

Wherein, the power operation interval includes: the power operation interval includes: and the maximum reverse power parameter and the maximum forward power parameter of the grid-connected point of the microgrid. According to the above-mentioned regulations on the positive and negative directions and signs of the power/current of the piconet, in this embodiment, the reverse power parameter of the grid-connected point is always a negative value, and the forward power parameter is always a positive value, and the magnitude of the reverse power parameter is based on the magnitude of the absolute value of the reverse power parameter, that is, the larger the absolute value of the reverse power parameter is, the larger the absolute value of the reverse power parameter is, where the maximum reverse power parameter is the maximum value of the absolute values in the reverse power parameters allowed by the grid-connected point of the piconet.

The amount of the power transmitted back by the first-level microgrid is determined by the power operation interval allowed by the first-level microgrid under the network scheduling device of the second-level microgrid. Therefore, the magnitude of the first-level microgrid back-transmission power cannot exceed the operation interval of the first-level microgrid.

In this embodiment, the maximum reverse power parameter of the piconet grid-connected point is P_-maxIndicating that the maximum forward power parameter is P_maxIs represented by, thus P_-max、0、P_maxThe number axis is divided into 4 intervals,as shown in FIG. 8, are respectively less than P_-maxInterval 1 of not less than P_-maxInterval 2 less than 0, P more than 0 and less than or equal to_maxInterval 3 of, and greater than P_maxInterval 4 of (a).

Note that the case equal to the boundary may be divided into any one of two adjacent sections. For example: is equal to P_-maxCan be divided into interval 1, in which case interval 2 is greater than P_-maxLess than 0. Based on this, the above interval division can be changed in many ways, and is not exemplified here.

And S703, the first microgrid control device acquires a power adjustment strategy of the second energy storage equipment.

The first microgrid control device has two schemes for acquiring the power adjustment strategy of the second energy storage device: one is that the first microgrid control device determines a power adjustment strategy of the second energy storage device according to the relation between the real-time power P of the grid-connected point of the first microgrid and the power operation interval allowed by the first microgrid; and the other is that the first microgrid control device receives a power adjustment strategy of the second energy storage equipment, which is sent by the second microgrid control device or the network scheduling device. The procedures of these two schemes will be described in detail below.

According to the scheme 1, the first microgrid control device determines a power adjustment strategy of the second energy storage equipment according to the real-time power P of the grid-connected point of the first microgrid and the power operation interval allowed by the first microgrid.

The first microgrid control device refreshes real-time data of the first microgrid at regular time (1-5 seconds), wherein the real-time data of the first microgrid comprises: the real-time power P of the microgrid grid-connected point and the real-time power of the second energy storage device.

For example, referring to fig. 5, the microgrid control device No. 2 refreshes real-time data of the microgrid No. 2. The specific real-time data of the No. 2 microgrid comprises the following data: the real-time power P of the No. 2 microgrid grid-connected point, the real-time power of a second energy storage device (an energy storage device connected with 10kV buses), and the like.

And the first microgrid control device compares the real-time power P of the grid-connected point with a set power operation interval in real time.

Optionally, if P is a negative value and P is greater than the maximum reverse power (i.e. in interval 2 of fig. 8), determining a power adjustment policy of the second energy storage device, where the power adjustment policy includes: increasing the discharge power of the second energy storage device or decreasing the charge power of the second energy storage device.

It should be noted that: and P is a negative value, which indicates that the current primary microgrid transmits power back to the secondary microgrid, and the discharge power of the second energy storage equipment can be properly increased or the charging power of the second energy storage equipment can be reduced by 50 kW-100 kW within the set power operation interval. However, if the second energy storage device has reached its maximum discharge power, or the second energy storage device needs to change its current charge-discharge state, then there is no need to adjust the power of the second energy storage device. The life of the second energy storage device can be affected because the charge-discharge state of the second energy storage device is frequently changed.

In addition, the case where P is equal to the maximum reverse power may also be performed according to the above power adjustment strategy.

Optionally, if P is a negative value and P is less than the maximum reverse power (i.e. in interval 1 of fig. 8), determining a power adjustment policy of the second energy storage device, where the power adjustment policy includes: reducing the discharge power of the energy storage device or increasing the charge power of the second energy storage device;

Optionally, if P is a positive value and P is less than the maximum forward power (i.e. in the interval 3 in fig. 8), determining a power adjustment policy of the second energy storage device, where the power adjustment policy includes: the discharge power of the second energy storage device is reduced or the charge power of the second energy storage device is increased.

It should be noted that, when the first-stage microgrid absorbs power to the second-stage microgrid, the discharge power of the second energy storage device needs to be properly reduced or the charging power of the second energy storage device needs to be increased by 50 to 100 kW. However, if the second energy storage device has reached its maximum charge power, or the second energy storage device needs to change its current charge-discharge state, or P exceeds its maximum forward power, then there is no need to readjust the power of the second energy storage device.

Optionally, if P is a positive value and P is greater than the maximum forward power (i.e. in the interval 4 of fig. 8), determining a power adjustment policy of the second energy storage device, where the power adjustment policy includes: increasing the discharge power of the second energy storage device or decreasing the charge power of the second energy storage device.

And in the scheme 2, the first microgrid control device receives a power adjustment strategy of the second energy storage equipment, which is sent by the second microgrid control device or the network scheduling device.

In this scheme, the power adjustment strategy of the second energy storage device is determined by the second microgrid control apparatus.

And the second microgrid control device receives the power operation interval allowed by the second microgrid and sent by the network scheduling device. And the second microgrid control device determines a power adjustment strategy of the second energy storage equipment according to the relation between the real-time power P of the grid-connected point of the second microgrid and the power operation interval allowed by the second microgrid. The specific process may refer to the specific implementation process in scheme 1, and is not described herein again.

The second microgrid control device may send the determined power adjustment policy for the second energy storage device to the first microgrid control device, or send the determined power adjustment policy to the network scheduling device, which then sends the power adjustment policy to the first microgrid control device, and the first microgrid control device controls the power of the second energy storage device according to the received power adjustment policy.

The second energy storage equipment can directly adjust the second-level microgrid on the high-voltage side of the voltage transformation equipment of the microgrid, so that transmission loss is reduced, more importantly, the second energy storage equipment can serve not only the first microgrid but also the surrounding second microgrid when the capacity is surplus, and the service range of the second energy storage equipment is expanded.

And S704, the first microgrid control device controls the power of the second energy storage equipment according to the power adjustment strategy of the second energy storage equipment.

By cycling the steps S703 to S704 at least once, and adding the second energy storage device in the power network, when the real-time power of the grid-connected point of the microgrid is greater than the maximum forward power, the discharge power of the second energy storage device is increased or the charge power of the second energy storage device is decreased, so that the real-time power of the PCC of the microgrid group is not too large, even if the demand of the microgrid on the power grid is not too large. When the real-time power of the grid-connected point of the microgrid is less than the maximum reverse power, the utilization rate of the capacity equipment in the microgrid is reduced without reducing the capacity power of the capacity equipment in the microgrid like the prior art.

And the second energy storage device has the characteristic of quick and bidirectional power response, and the adjustment of the second energy storage device is minute-level, so that the response is quicker compared with the adjustment of the power of the capacity generating device in the microgrid.

Specifically, the second energy storage device has a controller for controlling its own operation, and the first microgrid control apparatus may send the power adjustment policy obtained in step S703 to a controller (control interface) of the second energy storage device, so that the controller of the second energy storage device may control the operation state of the second energy storage device according to the adjustment value. The adjusting strategy can only control the second energy storage device to increase or decrease the charging and discharging power of the second energy storage device, and then the controller of the second energy storage device controls the second energy storage device by combining the adjusting strategy and a preset power adjusting value; the adjustment strategy may also include controlling the second energy storage device to increase or decrease its charge-discharge power, and also include a power adjustment value, and then the controller of the second energy storage device controls the second energy storage device according to the adjustment strategy.

The adjustment value may be a target power set for the power of the second energy storage device, may be a power value that needs to be increased or decreased by the second energy storage device (i.e., a difference between the target power and the power before adjustment), may also be a ratio that needs to be increased or decreased by the second energy storage device (i.e., a ratio between the difference between the target power and the power before adjustment), and the like; alternatively, the adjustment value may have positive and negative values, with positive values indicating an increase and negative values indicating a decrease. In short, the controller is only required to inform the direction and degree of adjustment required by the second energy storage device controlled by the controller.

The adjustment value may be calculated by using a predetermined algorithm.

For simplicity, a simple algorithm may be used in this embodiment. For example, the pre-regulation power may be set to P₀And the adjustment value is T, the set algorithm may be P₀+ T, wherein T is the power value required to be increased or decreased by the second energy storage device; or may be P₀+P₀T is now the proportion of the second energy storage device that needs to be increased or decreased. Of course, other reasonable algorithms are possible and will not be described in detail here.

It should be noted that, in a specific implementation process, the selection principle of the power adjustment strategy of the second energy storage device is as follows: the current state (charging or discharging state) of the second energy storage device is preferentially maintained and the power of its current state is reduced/increased. If the power of the second energy storage device is reduced to be below a preset threshold (for example, 10kW), and the control target is not reached yet, switching the charging and discharging state of the second energy storage device; and if the power of the second energy storage device is increased to the maximum power of the current state, the second energy storage device keeps the maximum power to operate.

For example, referring to fig. 5, the real-time power P of the piconet No. 2 is in the reverse direction, and in the first case: assume that P is greater than the maximum reverse power at this time and the second energy storage device is in a charging state. Then the adjustment policy for the second energy storage device may be determined to be: and firstly reducing the charging power of the second energy storage device, and circulating the steps S703-S704, wherein if the power of the second energy storage device is reduced to be less than 10kW after the nth circulation, and P is still larger than the maximum reverse power, the charging state of the second energy storage device is switched to the discharging state by the (n + 1) th circulation, and the discharging power of the second energy storage device is increased. In the second case: assume that P is greater than the maximum reverse power at this time and the second energy storage device is discharging. Then the adjustment policy for the second energy storage device may be determined to be: and increasing the discharge power of the second energy storage device, circulating the steps S703-S704, and if the discharge power of the second energy storage device is increased to the maximum value after the nth circulation, keeping the second energy storage device working at the maximum discharge power.

In short, the selection of the power adjustment strategy is an intelligent control according to the current working state of the second energy storage device. Therefore, the method for selecting the adjustment strategy according to the current working state of the second energy storage device can flexibly control when the adjustment is small so as to achieve the target, and avoids the problem that the second energy storage device is damaged in operation impedance due to frequent change of the charging and discharging states and influences the service life of the second energy storage device as much as possible.

The specific control flow of the above steps S703-S704 is described with reference to fig. 9(a), which takes the execution subject as the first microgrid control apparatus as an example, and the execution subject as the second microgrid control apparatus may refer to the following flow for determining the power adjustment strategy of the second energy storage device. Optionally, the specific steps are as follows:

and S91, the microgrid control device refreshes the real-time data of the microgrid controlled by the microgrid control device at regular time (1-5 seconds), wherein the real-time data of the microgrid comprises the real-time power P of the microgrid grid-connected point and the real-time power of the second energy storage equipment.

S92, judging whether P is negative value. If P is a negative value, S93 is performed, otherwise S96 is performed.

S93, judging whether P is less than P_-max. If P is less than P_-maxThen execution proceeds to S94; otherwise, S95 is executed.

S94, if the second energy storage device is in a discharging state, reducing the discharging power of the second energy storage device; or if the second energy storage device is in a charging state, the charging power of the second energy storage device is increased.

And the microgrid control device sends the adjustment strategy to a controller of the second energy storage equipment, and the second energy storage equipment controller adjusts the second energy storage equipment.

And S95, if the second energy storage device is in a discharging state, increasing the discharging power of the second energy storage device, or if the second energy storage device is in a charging state, decreasing the charging power of the second energy storage device.

S96, judging whether P is larger than P_maxIf P is greater than P_maxThen S97 is executed. Otherwise, S98 is executed.

And S97, if the second energy storage device is in a discharging state, increasing the discharging power of the second energy storage device, or if the second energy storage device is in a charging state, decreasing the charging power of the second energy storage device.

And S98, if the second energy storage device is in a discharging state, reducing the discharging power of the second energy storage device, or if the second energy storage device is in a charging state, increasing the charging power of the second energy storage device.

Alternatively, the specific control flow of the above steps S703-S704 may be executed in the following order, specifically, as follows, with reference to fig. 9(b),

firstly, executing S91; then, S96 is executed to determine whether P is greater than P_max(ii) a If greater than P_maxIf not, executing S97, otherwise, executing S93; s93, judging whether P is less than P_-max(ii) a If less than P_-maxIf not, executing S94, otherwise, executing S92; s92, judging whether P is a negative value; if P is negative, S95 is performed, otherwise S98 is performed.

The complete implementation process of the second embodiment and the third embodiment can be referred to as shown in fig. 10:

a second bus of the first microgrid is connected with a second energy storage device, and the first microgrid control device controls the first microgrid and the second energy storage device; and a second bus of the second microgrid is not connected with a second energy storage device, and the second microgrid control device controls the second microgrid. The following two schemes are possible.

Scheme 1, the steps are as follows:

s801a, the first microgrid control device sends the real-time operation parameters of the first microgrid to the network scheduling device;

s802, the network scheduling device receives real-time operation parameters of the first microgrid and obtains a power operation interval allowed by the first microgrid;

s803a, the network scheduling apparatus sends the power operation interval allowed by the first piconet to the first piconet controlling apparatus;

s804a, the first microgrid control device receiving the power operation interval sent by the network scheduling device, and determining a power adjustment policy of the second energy storage device;

s807, the first microgrid control device sends a power adjustment strategy of the second energy storage equipment to a controller of the second energy storage equipment;

and S808, the controller of the second energy storage device receives the power adjustment strategy sent by the first microgrid control device, and adjusts the power of the second energy storage device.

Scheme 2, the steps are as follows:

s801b, the second microgrid control device value sends real-time operation parameters of the second microgrid to the network scheduling device;

s802, the network scheduling device receives real-time operation parameters of the second microgrid and obtains a power operation interval allowed by the second microgrid;

s803b, the network scheduling apparatus sends the power operation interval allowed by the second piconet to the second piconet controlling apparatus;

s804b, the second microgrid control apparatus receives the power operation interval sent by the network scheduling apparatus, and determines a power adjustment policy of the second energy storage device;

s805b, the second microgrid control apparatus sends a power adjustment policy of the second energy storage device to the network scheduling apparatus;

s806b the network scheduling apparatus sending the power adjustment policy of the second energy storage device determined by the second piconet controlling apparatus to the first piconet controlling apparatus;

s807, the first microgrid control device sends the power adjustment strategy of the second energy storage equipment determined by the second microgrid control device to a controller of the second energy storage equipment;

Step S805c may also replace steps S805b and S806b in case 2.

S805c, the second microgrid control apparatus sends the power adjustment policy of the second energy storage device determined by the second microgrid control apparatus to the first microgrid control apparatus.

For details of the specific steps, reference may be made to embodiment two and embodiment three, which are not described again.

The embodiment of the invention provides a control method of a power network, which aims at the power network which jointly operates a plurality of micro-grids and is then connected with a power grid in a grid-connected mode. The microgrid control device sends real-time parameters to the network scheduling device at regular time, receives the allowed power operation intervals of each microgrid sent by the network scheduling device, determines a power adjustment strategy according to the relation between the P of the microgrid grid-connected point and the allowed power operation intervals, and controls second energy storage equipment of the microgrid to execute the power adjustment strategy. Therefore, the microgrid control device can determine a power adjustment strategy for the second energy storage equipment controlled by the microgrid control device according to the power operation interval sent by the network scheduling device, and adjust the second energy storage equipment according to the power adjustment strategy. The power network power control method and the power network power control device realize the rapid control of the power network power provided by the embodiment of the invention.

Example four

The embodiment of the present invention provides a network scheduling apparatus for an electric power network, where the electric power network is the above-mentioned electric power network, and the apparatus may be software or hardware, and the implementation of each functional module may refer to the second embodiment, which is not described herein again. As shown in fig. 11, the apparatus includes:

an obtaining unit 111, configured to obtain, by a network scheduling apparatus, a power operation interval allowed by any one of the micro grids in the micro grid group, where the power operation interval includes: the maximum reverse power parameter and the maximum forward power parameter of the grid-connected point of the microgrid;

a sending unit 112, configured to send the allowed power operation interval of the microgrid, obtained by the obtaining unit 111, to the microgrid control device of the microgrid, so that the microgrid control device determines the power adjustment strategy of the second energy storage device according to the real-time power P of the grid-connected point of the microgrid and the allowed power operation interval of the microgrid.

Optionally, the obtaining unit 111 is further configured to obtain a power operation interval allowed by the microgrid according to a preset time period.

Optionally, the obtaining unit 111 further includes a receiving subunit 1111, configured to receive the real-time operation parameters of the microgrid, which are sent by the microgrid control device of the microgrid, where the real-time operation parameters include: the method comprises the steps that real-time power parameters of a grid-connected point of the microgrid and power improving capacity and power reducing capacity of the microgrid are obtained, and the real-time power parameters are used for obtaining real-time power values;

a determining subunit 1112, configured to perform weighted summation on a real-time power value in a current time period of a grid-connected point of the microgrid and a real-time power value in a historical time period to obtain a power predicted value; correcting the power predicted value according to the power improving capacity or the power reducing capacity of the microgrid to obtain a power corrected value; and determining an interval containing the power correction value as an allowed power operation interval of the microgrid.

In this embodiment, the obtaining unit 111 may be implemented by an interface circuit with a receiving function on a control device of the power network and a processor, for example: parameters for obtaining the power operation interval can be obtained through the interface circuit, and then the processor obtains the power operation interval according to the parameters; of course, the hardware circuit may obtain the power operation interval according to these parameters. The interface circuit may be a receiver or an information receiving interface, for example. The transmitting unit 112 may be implemented by an interface circuit having a transmitting function on a control device of the power network, for example: the allowed power operation interval command of the microgrid can be transmitted through an interface circuit, for example, the interface circuit can be a transmitter or an information transmission interface. These units may be processors separately installed, or may be implemented by being integrated into one of the processors of the network scheduling apparatus of the network, or may be stored in a memory of the network scheduling apparatus of the network in the form of program codes, and the functions of the above units may be called and executed by one of the processors of the network scheduling apparatus of the network. The processor may be a Central Processing Unit (CPU), an Application Specific Integrated Circuit (ASIC), or one or more Integrated circuits configured to implement embodiments of the present invention.

The embodiment of the invention provides a network scheduling device, and aims at the power network provided by the embodiment of the invention, the network scheduling device determines an allowed power operation interval for a microgrid control device, so that the microgrid control device determines a power adjustment strategy of a second energy storage device according to the power operation interval.

EXAMPLE five

The embodiment of the present invention provides a microgrid control device, which is used in a power network, where the power network is the above power network, and the device may be software or hardware, and implementation of each functional module may refer to the third embodiment, and is not described herein again. As shown in fig. 12, the apparatus includes:

an obtaining unit 121, configured to obtain, by the first microgrid control apparatus, a power adjustment policy of the second energy storage device;

A control unit 122, configured to control the power of the second energy storage device by the first microgrid control apparatus according to the power adjustment strategy of the second energy storage device acquired by the acquisition unit 121.

Optionally, the obtaining unit 121 further includes: the receiving subunit 1211 is configured to, by the first piconet controlling device, receive a power operation interval allowed by the first piconet and sent by a network scheduling device, where the power operation interval includes: a maximum reverse power parameter and a maximum forward power parameter of a grid-connected point of the first piconet; the determining subunit 1212 is configured to determine a power adjustment policy of the second energy storage device according to the real-time power P of the grid-connected point of the first microgrid and the power operation interval allowed by the first microgrid;

optionally, the obtaining unit 121 further includes: the receiving subunit 1211 is further configured to receive, by the first microgrid control apparatus, a power adjustment policy of the second energy storage device, where the power adjustment policy is sent by a second microgrid control apparatus or the network scheduling apparatus.

Optionally, the determining subunit 1212 is specifically configured to determine, according to the real-time power P of the grid-connected point of the first microgrid and the power operation interval allowed by the first microgrid, the power adjustment strategy of the second energy storage device includes:

if the P is a negative value and the P is greater than the maximum reverse power, determining a power adjustment strategy of the second energy storage device, wherein the power adjustment strategy comprises: increasing the discharge power of the second energy storage device or decreasing the charge power of the second energy storage device;

and/or the presence of a gas in the gas,

if P is a negative value and P is less than the maximum reverse power, determining a power adjustment strategy of the second energy storage device, wherein the power adjustment strategy comprises: reducing the discharge power of the second energy storage device or increasing the charge power of the second energy storage device;

and/or the presence of a gas in the gas,

if P is a positive value and P is less than the maximum forward power, determining a power adjustment strategy of the second energy storage device, wherein the power adjustment strategy comprises: reducing the discharge power of the second energy storage device or increasing the charge power of the second energy storage device;

and/or the presence of a gas in the gas,

if P is a positive value and P is greater than the maximum forward power, determining a power adjustment strategy of the second energy storage device, wherein the power adjustment strategy comprises: increasing the discharge power of the second energy storage device or decreasing the charge power of the second energy storage device.

It should be noted that the acquiring unit 121 in this embodiment may be an interface circuit, such as a receiver or an information receiving interface, with a receiving function on a control device of the power network. The receiving subunit 1211 may be implemented by an interface circuit having a receiving function on a control device of the power network, for example: the allowed power operation interval of the microgrid may be received by an interface circuit, which may be, for example, a receiver or an information receiving interface. The other units may be processors separately installed, or may be implemented by being integrated into a certain processor of the control device of the power network, or may be stored in a memory of the control device of the power network in the form of program codes, and the certain processor of the control device of the power network calls and executes the functions of the above units. The processor described here is the same as in the fourth embodiment.

The embodiment of the invention provides a network scheduling device, and aims at the power network provided by the embodiment of the invention to realize the rapid power regulation of a first microgrid control device on second energy storage equipment.

EXAMPLE six

An embodiment of the present invention provides a control system of an electric power network, where the electric power network is the above-mentioned electric power network, and with reference to fig. 13, the control system includes: the network scheduling device according to the fourth embodiment and the microgrid control device according to the fifth embodiment. The implementation of each apparatus can refer to the above embodiments, and is not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may be physically included alone, or two or more units may be integrated into one unit. The integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.

The integrated unit implemented in the form of a software functional unit may be stored in a computer readable storage medium. The software functional unit is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute some steps of the methods according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. An electrical power network, comprising: n microgrids, wherein N is more than or equal to 2;

the N micro-grids are divided into M micro-grid groups, each micro-grid in each group is communicated through the tie line, each micro-grid group is communicated with a power grid power supply line through a common connection point PCC, only one access switch in each group is communicated with the power grid power supply line, a second bus of at least one micro-grid in the N micro-grids is connected with energy storage equipment, and M is larger than or equal to 1 and smaller than or equal to N.

2. The power network of claim 1, wherein each microgrid further comprises: and the high-voltage side switch of the transformation equipment is positioned between the first bus and the second bus.

3. A method of controlling an electrical power network, characterized in that the electrical power network is the electrical power network of claim 1 or 2;

4. The control method according to claim 3, wherein the obtaining of the allowed power operation interval of each microgrid in the microgrid group comprises:

and acquiring the allowed power operation interval of the microgrid according to a preset time period.

5. The control method according to claim 3 or 4, wherein the obtaining of the allowed power operation interval of each microgrid in the microgrid group comprises:

receiving real-time operation parameters of the microgrid, which are sent by a microgrid control device of the microgrid, wherein the real-time operation parameters comprise:

6. A method of controlling an electrical power network, characterized in that the electrical power network is the electrical power network of claim 1 or 2; the energy storage equipment is connected with a second bus of the first microgrid, and the energy storage equipment is controlled by a first microgrid control device of the first microgrid;

the control method comprises the following steps:

7. The control method according to claim 6,

the acquiring, by the first microgrid control apparatus, the power adjustment policy of the energy storage device includes: the first piconet controlling device receives a power operation interval allowed by the first piconet and sent by a network scheduling device, and the power operation interval includes: a maximum reverse power parameter and a maximum forward power parameter of a grid-connected point of the first piconet; determining a power adjustment strategy of the energy storage device according to the real-time power P of the grid-connected point of the first microgrid and the power operation interval allowed by the first microgrid;

or,

8. The control method according to claim 7,

the determining the power adjustment strategy of the energy storage device according to the real-time power P of the grid-connected point of the first microgrid and the power operation interval allowed by the first microgrid comprises:

and/or the presence of a gas in the gas,

9. A network scheduling apparatus for controlling a power network according to claim 1 or 2, wherein the apparatus comprises, for each micro grid group including the energy storage devices:

and the transmitting unit is used for transmitting the power operation interval allowed by the microgrid, which is acquired by the acquiring unit, to the microgrid control device of the microgrid, so that the microgrid control device determines a power adjustment strategy of the energy storage equipment according to the real-time power P of the grid-connected point of the microgrid and the power operation interval allowed by the microgrid.

10. A microgrid control apparatus for controlling a power network according to claim 1 or 2, the power network being a power network as claimed in claim 1 or 2, the energy storage device being connected to the second bus of the first microgrid, the energy storage device being controlled by the first microgrid control apparatus of the first microgrid; the device includes:

and the control unit is used for controlling the power of the energy storage equipment by the first microgrid control device according to the power adjustment strategy of the energy storage equipment acquired by the acquisition unit.

11. A control system for an electric power network, characterized in that the electric power network is the electric power network of claim 1 or 2, the control system comprising: the network scheduling apparatus of claim 9 and the piconet controlling apparatus of claim 10.