CN106374533B - Miniature energy network system - Google Patents

Abstract

The invention discloses a miniature energy network system, which comprises an energy management unit and a plurality of conversion units capable of realizing unidirectional or bidirectional conversion and flow of energy in the forms of AC/DC, DC/AC and AC/AC, wherein one side of each conversion unit is connected with a power generation unit, energy storage, an electric automobile or a load, and the other side is connected with a direct current bus or an alternating current bus through a metering unit and a controllable switch; the direct current bus is connected with the alternating current bus through the bidirectional DC/AC conversion unit and the controllable switch; the alternating current bus is connected with the transformer through the metering unit and the controllable switch, and the input end of the transformer is connected with the power grid. The invention adopts the hybrid energy network based on the alternating current bus and the direct current bus, combines energy metering and switching control, can effectively solve the requirement of the energy network based on the access of various energy sources of electric automobile charging, effectively solves the electric energy quality problem caused by the grid connection of a plurality of alternating current power supplies, improves the energy utilization efficiency, and utilizes energy scheduling to carry out local peak clipping and valley filling so as to realize the fine adjustment of the energy of the power grid.

Description

A micro energy network system

[Technical field]

The present invention belongs to the technical field of electric vehicle charging and smart grid, and in particular relates to a micro energy network system.

【Background technique】

Existing electric vehicles obtain electricity by connecting to 380Vac or 220Vac power grids through charging equipment. When multiple devices are connected to the grid, discrete loads are connected to the grid. Disorderly charging of electric vehicles leads to pollution of the grid and reduced efficiency of power utilization. Moreover, with the continuous development of electric vehicle charging and energy Internet technology, the traditional method of directly connecting multiple AC loads to the grid in parallel is no longer applicable to electric vehicle discharge. In addition, the application and access of distributed generation and energy storage technology on the user side puts forward new requirements for the traditional energy network structure, which has a greater negative impact on the quality of power grid power and how to use energy more efficiently.

The Chinese patent application with application number 201110268090.9 discloses an energy router for distributed power generation. This solution aims at the intermittent problem of distributed power generation, especially renewable energy distributed power generation, and proposes an energy router that coordinates and controls multiple distributed power sources. By using distributed power sources, each distributed power source and energy storage unit are connected to the industrial frequency AC bus of the energy router, which can not only supply power to local common loads and important loads, but also transmit electricity to the public power grid. However, this solution is an energy network device based on the AC bus, and does not perform separate metering and control for different energy sources. In addition, since there are multiple power generation devices connected in parallel on the AC bus, there is a lack of effective control of power quality issues and optimal energy utilization. The DC bus is not used to improve energy utilization efficiency, and there is no effective utilization of energy for electric vehicles.

The Chinese patent application with publication number CN101436778A discloses a microgrid networking method, which adopts a DC bus structure, and each power generation unit and load are connected to the DC bus, and connected to the distribution network through a grid-connected inverter when connected to the grid. However, this method is only based on the energy network of the DC bus, without separate measurement and control for different energy sources, without AC bus, and without effective energy utilization for electric vehicles.

The two most relevant documents above highlight the descriptions of energy networks based on AC bus and DC bus, respectively. Either method has limitations and problems. A single AC bus energy network or DC bus energy network cannot meet the existing needs, and a micro energy optimal utilization and interactive solution composed of electric vehicle charging, discharging, distributed generation, energy storage systems, etc., without precise metering and energy control.

In summary, the prior art has the following problems:

(1) A single energy network based on an AC bus or a DC bus cannot maximize energy utilization;

(2) Energy sources such as electric vehicle charging and discharging, distributed generation, and energy storage systems are not used and interacted efficiently;

(3) There is no separate measurement and control for different energy sources.

[Summary of the invention]

The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a hybrid micro energy network system based on a DC bus and an AC bus.

In order to achieve the above object, the present invention adopts the following technical solutions:

A micro energy network system comprises an energy management unit and a plurality of conversion units capable of realizing unidirectional or bidirectional conversion and flow of energy in the form of AC/DC, DC/DC, DC/AC and AC/AC, wherein one side of each conversion unit is connected to a power generation unit, energy storage, electric vehicle or load, and the other side is connected to a DC bus or an AC bus through a metering unit and a controllable switch; the DC bus is connected to the AC bus through a bidirectional DC/AC conversion unit and a controllable switch; the AC bus is connected to a transformer through a metering unit and a controllable switch, and the input end of the transformer is connected to a power grid; the energy management unit is electrically connected to each conversion unit, metering unit, controllable switch and transformer to control the flow direction and flow of electric energy; the power generation unit comprises a distributed AC power generation unit and a distributed DC power generation unit.

The present invention is further improved in that:

The conversion unit includes a unidirectional AC/DC conversion unit, a unidirectional DC/DC conversion unit, a unidirectional DC/AC conversion unit, a unidirectional AC/AC conversion unit, a bidirectional AC/DC conversion unit, a bidirectional DC/DC conversion unit, a bidirectional DC/AC conversion unit and a bidirectional AC/AC conversion unit.

One end of the unidirectional AC/DC conversion unit is connected to the distributed AC power generation unit, and the other end is connected to the DC bus through a metering unit and a controllable switch, so as to convert the distributed AC power generation energy into DC power.

One side of the unidirectional DC/DC conversion unit is connected to the distributed DC power generation unit, and the other end is connected to the DC bus through a metering unit and a controllable switch, so as to convert the distributed DC power generation into DC power of different voltage levels.

One side of the bidirectional DC/DC conversion unit is connected to a distributed DC energy storage unit or an electric vehicle, and the other end is connected to a DC bus through a metering unit and a controllable switch, and is used for bidirectional conversion of one DC power into another DC power with a different voltage level.

One side of the bidirectional AC/DC conversion unit is connected to a distributed AC energy storage unit or an electric vehicle, and the other end is connected to a DC bus through a metering unit and a controllable switch, for bidirectional conversion of AC power and DC power.

One end of the bidirectional AC/AC conversion unit is connected to an electric vehicle or an AC load, and the other end is connected to an AC busbar through a metering unit and a controllable switch, and is used for bidirectional conversion of electric vehicle AC power and industrial frequency AC power.

One end of the bidirectional DC/AC conversion unit is connected to an electric vehicle or a DC load, and the other end is connected to an AC bus through a metering unit and a controllable switch, and is used for bidirectional conversion of DC power and industrial frequency AC power.

The distributed AC power generation units and distributed DC power generation units include but are not limited to wind power generation, photovoltaic power generation, solar thermal power generation and fuel power generation equipment; the AC energy storage units and DC energy storage units include but are not limited to flywheel energy storage, battery packs and supercapacitors; the AC loads and DC loads include but are not limited to AC loads with supply voltages of 220Vac and 380Vac, and DC loads with a voltage range of 200-1000Vdc.

The power grid includes but is not limited to power grids with voltage levels of 10 kVac, 20 kVac and 35 kVac.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention adopts a hybrid energy network based on AC bus and DC bus, and combines energy metering and switch control, which can effectively solve the needs of energy networks based on multiple energy access for electric vehicle charging, effectively solve the power quality problems caused by the grid connection of multiple AC power sources, and improve energy utilization efficiency. It uses energy scheduling to perform local peak shaving and valley filling to achieve micro-scheduling of grid energy. The present invention adopts bidirectional energy conversion to achieve internal energy circulation, increases metering and controllable switches, and effectively manages energy. At the same time, it adopts a DC bus solution to reduce grid connection points to reduce the negative impact of power quality, and improves energy utilization efficiency. It deeply integrates distributed power generation, energy storage, electric vehicles and other distributed energy with different characteristics, and realizes collaborative interaction between different energies through effective energy management and control, and the energy flow is controllable and efficiently utilized.

【Brief Description of the Drawings】

FIG. 1 is a design diagram of a micro energy network system of the present invention.

【Detailed ways】

The present invention is further described in detail below in conjunction with the accompanying drawings:

Referring to Figure 1, the micro energy network system of the present invention includes: a unidirectional AC/DC conversion unit, a unidirectional DC/DC conversion unit, a unidirectional DC/AC conversion unit, a unidirectional AC/AC conversion unit, a bidirectional AC/DC conversion unit, a bidirectional DC/DC conversion unit, a bidirectional DC/AC conversion unit, a bidirectional AC/AC conversion unit, a DC bus, an AC bus, a metering unit, a controllable switch, a transformer, and an energy management unit.

One end of the unidirectional AC/DC conversion unit is connected to the distributed AC power generation unit, and the other end is connected to the DC bus through the metering unit and the controllable switch, so as to convert the distributed AC power generation into DC power;

One end of the unidirectional DC/DC conversion unit is connected to the distributed DC power generation unit, and the other end is connected to the DC bus through the metering unit and the controllable switch, which is used to convert the distributed DC power generation into DC power with different voltage levels;

One end of the unidirectional DC/AC conversion unit is connected to the DC load, and the other end is connected to the AC bus through the metering unit and the controllable switch, which is used to convert the industrial frequency AC power into the power required by the DC load.

One end of the unidirectional AC/AC conversion unit is connected to the AC load, and the other end is connected to the AC bus through the metering unit and the controllable switch, and is used to convert the industrial frequency AC power into the power required by the AC load.

One end of the bidirectional AC/DC conversion unit is connected to an AC energy storage unit or an electric vehicle, and the other end is connected to a DC bus through a metering unit and a controllable switch, and is used for bidirectional conversion of AC power and DC power.

One end of the bidirectional DC/DC conversion unit is connected to a DC energy storage unit or an electric vehicle, and the other end is connected to a DC bus through a metering unit and a controllable switch, and is used for bidirectional conversion of one DC power into another DC power with a different voltage level.

One end of the bidirectional DC/AC conversion unit is connected to an electric vehicle or a DC bus, and the other end is connected to a metering unit or a controllable switch, and is used for bidirectional conversion of a DC power into an industrial frequency AC power.

One end of the bidirectional AC/AC conversion unit is connected to the electric vehicle, and the other end is connected to the AC bus through a metering unit and a controllable switch, and is used for bidirectional conversion of the AC power of the electric vehicle with the industrial frequency AC power.

The DC bus is used to gather DC power with the same voltage characteristics onto one bus.

The AC bus is used to gather AC power with the same characteristics onto one bus.

The metering unit is used to measure the flow direction, energy amount, etc. of AC power or DC power.

The controllable switch is used to control the energy flow in one direction or two directions.

One end of the transformer is connected to the AC bus through a controllable switch and a metering unit, and the other end is connected to the power grid, so as to convert the power of the power grid into industrial frequency AC power.

The energy management unit connects all conversion units, metering units, controllable switches, transformers and other equipment through communication technology, collects information from each device, and controls the flow direction and flow of electric energy, so as to realize that the energy of distributed DC/AC power generation units flows directly to electric vehicles or AC/DC energy storage units through the DC bus, or the DC energy of AC/DC energy storage units directly interacts with the electric energy of electric vehicles through the DC bus. Moreover, after the energy of distributed power generation units, energy storage units and electric vehicles is converted through the DC bus and DC/AC, the electric energy flows directly to other electric vehicles or loads on the same AC bus through the AC bus.

Principle of the present invention:

The present invention has an energy network based on both a DC bus and an AC bus. The energy connected to the DC bus and the AC bus can respectively realize local internal energy interaction, realize on-site energy consumption and efficient utilization. By adopting a bidirectional energy conversion unit, various forms of energy bidirectional conversion and flow such as AC/DC, DC/DC, DC/AC, and AC/AC can be realized. Each conversion unit is connected by a metering unit and a controllable switch to realize refined energy metering and control. Distributed energy sources with various characteristics such as distributed power generation, energy storage, and electric vehicles are combined into a DC microgrid, and energy is efficiently utilized and managed through an energy management unit, while reducing the number of industrial frequency AC grid connection points and reducing the negative impact on the quality of the power grid.

The energy management unit collects all-round information on all devices in the microgrid, and dispatches distributed generation, energy storage, and other electric vehicle energy to meet the needs of electric vehicle charging or load. According to the peak, flat, and valley characteristics of electricity consumption in the microgrid, it dispatches distributed generation, energy storage, and electric vehicle charging and discharging to achieve peak shaving and valley filling in the microgrid. According to the peak, flat, and valley characteristics of the power grid, it dispatches distributed generation, energy storage, and electric vehicle discharge during peak hours to achieve no or less electricity from the power grid, and more electricity during valley hours to achieve peak shaving and valley filling of the power grid. According to the transformer configuration capacity and the power demand of the load in the microgrid, it dynamically dispatches distributed generation, energy storage, and electric vehicle discharge to ensure that the power consumption capacity in the microgrid does not exceed the transformer capacity, and a small-capacity transformer can meet the large-capacity power load demand.

Functions of each conversion unit of the present invention:

Unidirectional AC/DC conversion unit: a unit that converts AC power into DC power in one direction. The AC voltage includes but is not limited to 220Vac or 380Vac.

Unidirectional DC/DC conversion unit: unidirectionally converts DC power in one voltage range into DC power in another voltage range.

Unidirectional DC/AC conversion unit: a voltage range of direct current is converted into industrial frequency alternating current in one direction.

One-way AC/AC conversion unit: an AC power is converted into AC power in one direction, the AC voltage includes but is not limited to 220Vac or 380Vac, including the voltage before and after the conversion is equal.

Bidirectional AC/DC conversion unit: bidirectional conversion of AC and DC, AC voltage includes but is not limited to 220Vac or 380Vac.

Bidirectional DC/DC conversion unit: Bidirectional conversion of DC power in one voltage range to DC power in another voltage range, including equal voltage values before and after the conversion.

Bidirectional DC/AC conversion unit: a bidirectional conversion between direct current and industrial frequency alternating current within a voltage range.

Bidirectional AC/AC conversion unit: bidirectional conversion of one alternating current to another alternating current, the AC voltage includes but is not limited to 220Vac or 380Vac, including that the voltage values before and after the conversion are equal.

DC bus, AC bus: The DC bus voltage range is 200-1000Vdc, and the AC bus is 380Vac, including but not limited to metal busbars, cables, and connectors.

Metering unit: AC metering and DC metering, a unit that measures the direction and flow of electric energy, and can also feedback values such as voltage, current, phase, active power, reactive power, power factor, frequency, direction and magnitude of electric energy, including but not limited to sensors, metering modules or meters.

Controllable switches: All switches with feedback node signals.

Transformer: A device that converts grid power into 380Vac. The grid voltage level is not limited to 10kVac, 20kVac, and 35kVac.

Energy management unit: A unit with communication functions and data collection, analysis and processing capabilities. Including but not limited to modules or devices containing MCU or CPU. Communication mode: wired, wireless, or power line carrier.

Distributed AC/DC power generation units, including but not limited to wind power generation, photovoltaic power generation, solar thermal power generation, fuel power generation and other equipment;

AC/DC energy storage units, including but not limited to flywheel energy storage, battery packs, supercapacitors, etc.

Electric vehicles include pure electric vehicles and hybrid electric vehicles that can be charged or discharged by AC.

AC/DC loads, including but not limited to loads with a supply voltage of 220Vac, 380Vac, and DC loads with a voltage range of 200-1000Vdc.

Power grids, including but not limited to power grids with voltage levels of 10kVac, 20kVac, and 35kVac.

Each conversion unit of the present invention can adopt a conversion unit with a metering unit and a controllable switch, without an external metering unit and a controllable switch. At the same time, the AC bus of the present invention can be directly connected to the 380Vac power grid without a transformer; the connection of each conversion unit, metering unit and controllable switch of the present invention has no order of precedence; the electric vehicle can be connected to the conversion unit as an energy storage unit.

The above contents are only for explaining the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims (3)

1. The miniature energy network system is characterized by comprising a unidirectional AC/DC conversion unit, a unidirectional DC/AC conversion unit, a unidirectional AC/AC conversion unit, a bidirectional AC/DC conversion unit, a bidirectional DC/AC conversion unit, a bidirectional AC/AC conversion unit, a direct current bus, an alternating current bus, a metering unit, a controllable switch, a transformer and an energy management unit; the direct current bus is connected with the alternating current bus through the bidirectional DC/AC conversion unit and the controllable switch; the alternating current bus is connected with the transformer through the metering unit and the controllable switch, and the input end of the transformer is connected with the power grid; the energy management unit is electrically connected with each conversion unit, each metering unit, each controllable switch and each transformer, is used for controlling the flow direction and the flow of electric energy, and is used for dispatching the energy sources of the distributed power generation units, the energy storage units and other electric vehicles according to the charging or load requirements of the electric vehicles so as to meet the requirements; according to the peak-to-valley characteristics of the power consumption in the micro energy network system, the distributed power generation unit, the energy storage unit and the electric vehicle are scheduled to charge and discharge to realize peak clipping and valley filling in the micro energy network system; according to the peak-to-valley characteristics of the power grid, the distributed power generation unit, the energy storage unit and the electric automobile are scheduled to discharge at peak time to realize no power taking or less power taking to the power grid, and the power is used for a plurality of purposes at valley time; dynamically scheduling the discharge of the distributed power generation unit, the energy storage unit and the electric automobile according to the configuration capacity of the transformer and the power consumption requirement condition of the load in the micro-grid; the distributed power generation unit comprises a distributed alternating current power generation unit and a distributed direct current power generation unit; the energy storage unit comprises an alternating current energy storage unit and a direct current energy storage unit;

one end of the unidirectional AC/DC conversion unit is connected with the distributed AC power generation unit, and the other end of the unidirectional AC/DC conversion unit is connected with the DC bus through the metering unit and the controllable switch and is used for converting the distributed AC power generation electric energy into DC electric energy;

One end of the unidirectional DC/DC conversion unit is connected with the distributed DC power generation unit, and the other end of the unidirectional DC/DC conversion unit is connected with the DC bus through the metering unit and the controllable switch and is used for converting the distributed DC power generation electric energy into DC electric energy with different voltage levels;

one end of the unidirectional DC/AC conversion unit is connected with a direct current load, and the other end of the unidirectional DC/AC conversion unit is connected with an alternating current bus through the metering unit and the controllable switch and is used for converting power frequency alternating current electric energy into electric energy required by the direct current load;

one end of the unidirectional AC/AC conversion unit is connected with an alternating current load, and the other end of the unidirectional AC/AC conversion unit is connected with an alternating current bus through the metering unit and the controllable switch and is used for converting power frequency alternating current electric energy into electric energy required by the alternating current load;

One end of the bidirectional AC/DC conversion unit is connected with the AC energy storage unit or the electric automobile, and the other end of the bidirectional AC/DC conversion unit is connected with the DC bus through the metering unit and the controllable switch and is used for bidirectional conversion of energy of AC electric energy and DC electric energy;

One end of the bidirectional DC/DC conversion unit is connected with the direct current energy storage unit or the electric automobile, and the other end of the bidirectional DC/DC conversion unit is connected with the direct current bus through the metering unit and the controllable switch and is used for bidirectionally converting the energy of one type of direct current electric energy and the energy of the other type of direct current electric energy with different voltage levels;

One end of the bidirectional DC/AC conversion unit is connected with the electric automobile, and the other end of the bidirectional DC/AC conversion unit is connected with an alternating current bus through the metering unit and the controllable switch and is used for bidirectional conversion of energy of direct current electric energy and power frequency alternating current electric energy;

One end of the bidirectional AC/AC conversion unit is connected with the electric automobile, and the other end of the bidirectional AC/AC conversion unit is connected with an alternating current bus through the metering unit and the controllable switch and is used for bidirectional conversion of energy of alternating current electric energy of the electric automobile and power frequency alternating current electric energy.

2. The micro energy network system of claim 1, wherein the distributed ac power generation unit and the distributed dc power generation unit comprise wind power generation, photovoltaic power generation, photo-thermal power generation, and fuel power generation equipment; the alternating current energy storage unit and the direct current energy storage unit comprise flywheel energy storage, a storage battery pack and a super capacitor; the ac load and the dc load include ac loads of which supply voltages are 220Vac and 380Vac, and dc loads of which voltage ranges from 200 to 1000 Vdc.

3. The micro energy network system of claim 1, wherein the power grid comprises power grids having voltage levels of 10kVac, 20kVac, and 35 kVac.