CN104078982A - Method for switching from grid-connected operation mode to off-network operation mode of microgrid based on load control - Google Patents

Abstract

The invention discloses a method for switching from a grid-connected operation mode to an off-network operation mode of a microgrid based on load control. Control devices in the microgrid achieve quick communication by means of an EPON optical fiber device, modeling is carried out in the whole microgrid on the basis of a GOOSE mechanism of 61850, quick switching of switching value information, analog quantity information and trip information of the whole microgrid is achieved, a part of power generation devices or loads are shut off according to generation capacity and load situations of the microgrid and the stability margin of an energy storage system during the process that the microgrid is switched from the grid-connected operation mode to the off-network operation mode, and accordingly stable off-network operation of the microgrid can be guaranteed. According to the method, GOOSE modeling is carried out on the switching value and the analog quantity of the power value P of the microgrid, and the load capacity problem of the microgrid during off-network operation is dynamically solved through load control.

Description

A kind of micro-electrical network of controlling based on load is grid-connected to be arrived from network operation mode switching method

Technical field

The invention discloses a kind of micro-electrical network and switch a kind of mentality of designing from network operation pattern by the pattern that is incorporated into the power networks, relate to distribution field, relaying protection field and communication field.

Background technology

Be subject to the increase in demand of global energy and the impact of environmental pollution, various countries carry forward vigorously development wind power generation, solar power generation and other clean electric power generation technology in the world, China also helps generation of electricity by new energy in policy, plan according to " 12 ", government is subsidized distributed power generation rate for incorporation into the power network, distributed power source supplements as large electrical network, accesses on the spot power distribution network, and distributed photovoltaic power generation online policy is decontroled at present.Distributed power generation belongs to intermittent energy source, has unsteadiness, can cause fluctuation and the flickering of system voltage, and distributed power generation and energy-storage system are formed to micro-electrical network, can effectively stabilize the fluctuation of voltage.

The operational mode of micro-electrical network is divided into the mode of being incorporated into the power networks and from network operation mode, generally micro-electrical network and power distribution network are incorporated into the power networks, and when the abnormal or Distribution Network Failure of superior system, micro-electrical network band portion important load is from network operation in V/F pattern.Micro-electrical network is converted to from the process of network operation pattern time by the pattern of being incorporated into the power networks, and in microgrid, generating and load capacity inconsistent, stablize control by energy-storage system to micro-electrical network, plays a part variable load plant.As enough large in energy storage system capacity, micro-electrical network can stable operation, but the cost of investment of energy-storage system is very high, and energy-storage battery average life problem, and the stable solution cost performance of this micro-electrical network is not high.If micro-electrical network is transferred in off-grid process by grid-connected, inner micro-electrical network point generating or unessential load are cut away, make to generate electricity with the unbalance control of load in the stable control nargin of energy-storage system in microgrid, that can realize and switch from net seamlessly transits, ensure important load reliable power supply in micro-electrical network, can greatly reduce the investment of energy-storage system.Switching load or generating in the time that the active of micro-electrical network allows to grow from net; be switched to again micro-electrical network from network operation mode; after Distribution Network Failure or superior system dead electricity; for the energy storage inverter that possesses low voltage ride-through function; the low voltage crossing time, 0 voltage crossing time was generally no more than 150ms, therefore at 625ms; require switching load or generate electricity and be switched to from the time of net stable operation to be generally no more than 150ms, otherwise the shutdown of energy storage inverter.

In recent years, computer technology, mechanics of communication, optical fiber technology fast development, EPON technology is used in a large number in distribution automation.If the GOOSE rapid communication mechanism of IEC61850 is carried out to effective integration with EPON, can effectively reduce investment, can realize dynamic load balancing control in micro-electrical network, ensure that micro-electrical network is from net stable operation.

Summary of the invention

Object:

Technical problem to be solved by this invention is the defect that overcomes prior art, provide a kind of micro-electrical network based on load control grid-connected arriving from network operation mode switching method, provide a kind of micro-electrical network to switch a kind of new mentality of designing from network operation pattern by the pattern that is incorporated into the power networks, that can realize and switch from net takes over seamlessly, and ensures important load reliable power supply in micro-electrical network.

Technical scheme:

Main technical content of the present invention is as follows: rely on the EPON optical-fibre communications of power distribution network as communication system, utilize the GOOSE communication mechanism of ICE61850 to carry out the snap information exchanges such as switching value, analog quantity, tripping operation information, transfer to by being incorporated into the power networks in the process of network operation at micro-electrical network, dynamic calculation cut-out generating or load, form generating and the balance of loading in micro-electrical network, ensure that micro-electrical network is from net safe and stable operation, comprise four steps:

1, in micro-electrical network, between each protection measure and control device and micro-grid mode control device, form the GOOSE mechanism communication network based on ICE61850 by switch and EPON.

2, the GOOSE mechanism of micro-electrical network the whole network based on ICE61850 is carried out the whole network modeling; it is being supported on the basis that the information such as switching value, trip signal transmit; also support the transmission of GOOSE analog quantity, in micro-electrical network, the analog quantity such as running status switching value and active power of each protection measure and control device can be given micro-grid mode control device on the net by GOOSE.

3, micro-electrical network internal loading or generating, according to characteristic and importance, can be excised priority level initializing by configuration file.

4, the inspection isolated island from net order or the transmission of grid-connected point interface device that micro-grid mode control device reception higher level supervisory control system issues starts from netting after order, can first calculate micro-electrical network current power vacancy, and cut-out generating or load, ensure the relative equilibrium of power between the interior generating of micro-electrical network and load, disconnect again and site switch, control energy storage inverter and switched to from network operation mode by the mode of being incorporated into the power networks.

Load or generating equipment excision order first configure by configuration file;

Cutting load is divided into the many wheels of many groups, wherein first group is sorted according to branch, second group is sorted according to segmentation, the 3rd group is sorted according to circuit, excision order be followed successively by first group of first round, first group second take turns, the like, second group of first round, second group second take turns, the like, the 3rd group of first round, the 3rd group second take turns, the like;

Cut generating equipment according to taking turns one group, the order of excision is GOOSE trip signal more.

In step (4), receiving the inspection isolated island from net order or grid-connected point interface device of higher level's supervisory control system when mode transition controller starts after net order, first calculate the power shortage of micro-operation of power networks, in the time that power shortage is less than the stability margin of energy storage inverter PCS, directly assign from the preset control command of net to energy storage inverter PCS, disconnect and site switch, energy storage inverter PCS transfers V/F mode of operation to through time delay after receiving this order, and micro-electrical network is from network operation; When power shortage be greater than energy storage inverter PCS from net stability margin time, excise generating equipment or load according to excision order, make micro-electrical network meet the condition of stable operation, assign from the preset control command of net to energy storage inverter PCS again, disconnect and site switch, energy storage inverter PCS transfers V/F mode of operation to through time delay after receiving this order, and micro-electrical network is from network operation.

When $|\stackrel{\·}{P}\mathrm{pcs}+\stackrel{\·}{P}\mathrm{pcc}|\≥\mathrm{KPpcszd}$ Time,

Carry out according to excision order $|\stackrel{\·}{P}\mathrm{pcs}+\stackrel{\·}{P}\mathrm{pcc}|-\left|\stackrel{\·}{P}\mathrm{li}\right|$ Or $|\stackrel{\·}{P}\mathrm{pcs}+\stackrel{\·}{P}\mathrm{pcc}|-\left|\stackrel{\·}{P}\mathrm{pi}\right|,$ And the load of record needs excision or the switch sequence number of generating equipment, until then give each power control or load control unit by GOOSE communication by trip signal multicast, power control or load control unit, according to the GOOSE order excision respective switch of concluding a bargin, make micro-electrical network meet the condition of stable operation;

Wherein be respectively energy storage inverter PCS, grid-connected point interface device on send power, for sending power on each load control unit, for sending power on each power control, for energy storage inverter PCS from network operation stability margin.

When $|\stackrel{\·}{P}\mathrm{pcs}+\stackrel{\·}{P}\mathrm{pcc}|\≥\mathrm{KPpcszd}$ Time, and $\stackrel{\·}{P}\mathrm{pcs}+\stackrel{\·}{P}\mathrm{pcc}>0$ Time, excision generating equipment.

When $|\stackrel{\&CenterDot;}{P}\mathrm{pcs}+\stackrel{\&CenterDot;}{P}\mathrm{pcc}|\&GreaterEqual;\mathrm{KPpcszd}$ Time, and $\stackrel{\&CenterDot;}{P}\mathrm{pcs}+\stackrel{\&CenterDot;}{P}\mathrm{pcc}<0$ Time, excision load.

The beneficial effect that the present invention reaches:

1, by EPON (Ethernet Passive Optical Network, Ethernet passive optical network) light splitting composition optical-fibre communications net, the GOOSE rapid communication mechanism of IEC61850 is applied to EPON system, realize micro-electrical network the whole network snap information exchange, can reduce optical fiber and repeat to lay.Switching value and the performance number P analog quantity etc. of the method to micro-electrical network carried out GOOSE modeling, logical overloading control, load capacity when dynamically having solved micro-electrical network and transferring to from network operation.

2, carry out dynamic load balancing calculating according to the performance number of the whole network, transfer to by being incorporated into the power networks at micro-electrical network from cut-out load or generator unit fast in network operation process, effectively improve the utilance of distributed power source, realize micro-electrical network and transfer taking over seamlessly from network operation to by grid-connected.

3, in the time of system dead electricity, can ensure can, from network operation, ensure the reliable power supply of important load in microgrid.

Brief description of the drawings

Fig. 1 is GOOSE Communication Model schematic diagram;

Fig. 2 is pattern switch control logic block diagram;

Fig. 3 is rack schematic diagram of the micro-electrical network of example;

Fig. 4 is the micro-electrical network GOOSE of example communication network schematic diagram.

Embodiment

For further setting forth technological means of the present invention, below in conjunction with accompanying drawing and example, specific embodiments of the present invention is described in detail.

Rely on the EPON communication system of power distribution network, set up the rapid communication net of the GOOSE mechanism based on IEC61850 in micro-electrical network between each control device, model is as Fig. 1.

The GOOSE mechanism of micro-electrical network based on IEC61850 is carried out communication modeling, and the apparatus GOOSE models such as mode transition controller, grid-connected point interface device, power control, energy storage inverter PCS are as following table:

Load or generating excision order need first to configure by configuration file, cutting load is divided into the many wheels of many groups, wherein first group is sorted according to branch, second group is sorted according to segmentation, the 3rd group is sorted according to circuit, excision order be followed successively by first group of first round, first group second take turns ... second group of first round, second group second take turns ... the 3rd group of first round, the 3rd group second take turns ... cut generating generally according to wheel more than a group, the order of excision is GOOSE trip signal, need in Communication Model, carry out modeling.

Mode transition controller receives the GOOSE analog quantity of each rating of set value P in micro-electrical network in real time, and the direction of P is pointed to circuit as positive direction taking micro-electrical network bus.Receiving the inspection isolated island from net order or grid-connected point interface device of higher level's supervisory control system when mode transition controller starts after net order, first calculate the power shortage of micro-operation of power networks, in the time that power shortage is less than the stability margin of energy-storage system PCS, directly assign from the preset control command of net to energy-storage system PCS, disconnect and site switch, PCS transfers V/F mode of operation to through short time delay after receiving this order, and micro-electrical network is from network operation.When power shortage be greater than energy storage inverter PCS from net stability margin time, work as

$|\stackrel{\&CenterDot;}{P}\mathrm{pcs}+\stackrel{\&CenterDot;}{P}\mathrm{pcc}|\&GreaterEqual;\mathrm{KPpcszd}$ Time,

Carry out according to excision order $|\stackrel{\&CenterDot;}{P}\mathrm{pcs}+\stackrel{\&CenterDot;}{P}\mathrm{pcc}|-\left|\stackrel{\&CenterDot;}{P}\mathrm{li}\right|$ Or $|\stackrel{\&CenterDot;}{P}\mathrm{pcs}+\stackrel{\&CenterDot;}{P}\mathrm{pcc}|-\left|\stackrel{\&CenterDot;}{P}\mathrm{pi}\right|$ , and record the switch sequence number that needs excision, until then give each device by GOOSE communication by trip signal multicast, each device is according to the GOOSE order excision respective switch of concluding a bargin, make micro-electrical network meet the condition of stable operation, assign from the preset control command of net to energy-storage system PCS again, disconnect and site switch, PCS transfers V/F mode of operation to through short time delay after receiving this order, and micro-electrical network is from network operation, and logic flow is shown in Fig. 2.

Wherein be respectively energy storage inverter PCS, grid-connected point interface device on send power, for sending power on each load control unit, for sending power on each power control, for energy storage inverter PCS from network operation stability margin.

Example explanation

In micro-electric network model of Fig. 3 example, the power direction of the each control appliance of micro-electrical network points to circuit by bus, Kp1, Kp2, Kp3, Kp4 is respectively power supply connecting valve, each power supply generate output is 400KW, all install power control unit, Kpcc is and site switch, install grid-connected point interface device, Kpcs connects energy storage inverter PCS, be 300KW from net stability margin, Kl01, Kl02, Kl03, Kl04 is four outlet switchs, installing load control unit, Kf1, Kf2, Kf3 is the block switch on load outlet Kl04, installing load control unit, Kl11, Kl12, Kl21, Kl22, Kl31, Kl32, Kl41, Kl42 is the branch switch on load outlet Kl04, each load capacity 150KVA of branch, separately having can not cutting load 1, 2 capacity.

GOOSE communication network can carry out networking by switch and EPON, and model is Fig. 4, and GOOSE communication modeling is as follows:

If load significance level is respectively from high to low: Kl12, Kl31, Kl2l, Kl41, Kl42, Kl11, Kl32, Kl22, the significance level of circuit is respectively from high to low: circuit Kl01, Kl02, Kl03, Kl04, arrange cutting load order by configuration file and be:

The first group of first round: Kl22

Take turns for first group second: Kl32

First group of third round: Kl11

First group of fourth round: Kl42

Take turns for first group the 5th: Kl41

Take turns for first group the 6th: Kl2l

Take turns for first group the 7th: Kl31

Take turns for first group the 8th: Kl12

The second group of first round: Kf3

Take turns for second group second: Kf2

Second group of third round: Kf1

The 3rd group of first round: Kl04

Take turns for the 3rd group second: Kl03

The 3rd group of third round: Kl02

The 3rd group of fourth round: Kl01

The order that puts into operation of supposing power supply is respectively Kp01, Kp02, Kp03, Kp04, and power supply excision order is respectively:

The first group of first round: Kp04

Take turns for first group second: Kp03

First group of third round: Kp02

First group of fourth round: Kp01

For simplified illustration, suppose that Kl01, Kl02, Kl03 all disconnect, only to give an example with Kl04 circuit, micro-electrical network is in the time being incorporated into the power networks, and mode transition controller is being received after the inspection isolated island order of net order or grid-connected point apparatus, is being had following operating condition:

1, generating is greater than load, and power difference exceedes the stability margin of energy storage inverter:

Suppose all full power generatings of 4 power supplys, be-400KW of generated output, can not cutting load 1, 2 work as preload is 100KVA, it is 50KVA that each branch works as preload, current power difference Ppcc+Ppcs=-(4*400+2*100+8*50)=1000K, exceed energy storage inverter from net stability margin 300K, and be greater than 0, need excision generating, according to excision order, calculate as excision Kp04, after Kp03, power difference is Ppcc+Ppcs=-(2*400+2*100+8*50)=200K, be less than energy storage inverter from net stability margin, mode transition controller generates Kp04, the GOOSE trip signal of Kp03, and control micro-electrical network and transfer to from network operation mode.

2, the power difference of generating and load is within the scope of the stability margin of inverter:

Suppose 2 power supply full power generatings, be-400KW of generated output, 2 power supplys are stopped transport, can not cutting load 1,2 be 100KVA when preload, it is 50KVA that each branch works as preload, and current power difference Ppcc+Ppcs=-(2*400+2*100+8*50)=200K, is less than energy storage inverter from net stability margin 300K, mode transition controller does not generate GOOSE trip signal, only controls micro-electrical network and transfers to from network operation mode.

3, generating is less than load, and power difference exceedes the stability margin of energy storage inverter, and cut-out branched line can meet the stability requirement of micro-electrical network:

Suppose 2 power supply full power generatings, be-400KW of generated output, 2 power supplys are stopped transport, can not cutting load 1, 2 work as preload is 400KVA, it is 90KVA that each branch works as preload, current power difference Ppcc+Ppcs=-(2*400+2*400+8*90)=-720K, exceed energy storage inverter from net stability margin 300K, and be less than 0, need excision load, according to excision order, calculate as the excision Kl22 of branch, Kl32, Kl11, Kl42, after Kl41, power difference is Ppcc+Ppcs=-(2*400+2*400+3*90)=270K, be less than energy storage inverter from net stability margin 300K, mode transition controller generates Kl22, Kl32, Kl11, Kl42, the GOOSE trip signal of Kl41, and control micro-electrical network and transfer to from network operation mode.

4, generating is less than load, and power difference exceedes the stability margin of energy storage inverter, excises whole branched lines and can't meet the stability requirement of micro-electrical network

Suppose 1 power supply generating, generated output is-300KW, 3 power supplys are stopped transport, can not cutting load 1, 2 work as preload is 320KVA, it is 50KVA that each branch works as preload, current power difference Ppcc+Ppcs=-(300+2*320+8*50)=-740K, exceed energy storage inverter from net stability margin 300K, and be less than 0, need excision load, according to excision order, calculate and take turns after load all cuts away when first group eight, power difference is Ppcc+Ppcs=-(300+2*320)=-340K, still exceed energy storage inverter from net stability margin, cancel first group of excision order, change by second group of excision order and excise, according to excision order, calculate as excision Kf3, after Kf2, power difference is Ppcc+Ppcs=-(300+320+4*50)=-220K, be less than energy storage inverter from net stability margin, mode transition controller generates Kf3, the GOOSE trip signal of Kf2, and control micro-electrical network and transfer to from network operation mode.

Claims (6)

1. grid-connected the arriving from network operation mode switching method of micro-electrical network of controlling based on load, it is characterized in that: in micro-electrical network, each control appliance utilizes EPON fiber plant rapid communication, GOOSE mechanism the whole network modeling based on 61850, realize the switching value information of micro-electrical network the whole network, analog quantity information, the quick exchange of tripping operation information, transfer to from the pattern of being incorporated into the power networks from network operation mode process at micro-electrical network, according to micro-grid generation capacity, the stability margin of load condition and energy-storage system, cut-out generating equipment or load, ensure that micro-electrical network can be from net stable operation, specifically comprise the following steps:

(1) in micro-electrical network, between each protection measure and control device and micro-grid mode switching control, form the GOOSE mechanism communication network based on ICE61850 by switch and EPON;

(2) the GOOSE mechanism of micro-electrical network the whole network based on ICE61850 is carried out the whole network modeling, it is being supported on the basis that switching value, trip signal information transmit, also support the transmission of GOOSE analog quantity, in micro-electrical network, running status switching value and the active power analog quantity of each protection measure and control device are given micro-grid mode switching control on the net by GOOSE;

(3) micro-electrical network internal loading or generating equipment, according to characteristic and importance, are excised priority level initializing by configuration file;

(4) the inspection isolated island from net order or the transmission of grid-connected point interface device that micro-grid mode switching control reception higher level supervisory control system issues starts from netting after order, first calculate micro-electrical network current power vacancy, and cut-out generating equipment or load, ensure the relative equilibrium of power between the interior generating equipment of micro-electrical network and load, disconnect again and site switch, control energy storage inverter and switched to from network operation mode by the mode of being incorporated into the power networks.

2. micro-electrical network of controlling based on load according to claim 1 is grid-connected to from network operation mode switching method, it is characterized in that: load or generating equipment excision order first configure by configuration file;

Cutting load is divided into the many wheels of many groups, wherein first group is sorted according to branch, second group is sorted according to segmentation, the 3rd group is sorted according to circuit, excision order be followed successively by first group of first round, first group second take turns, the like, second group of first round, second group second take turns, the like, the 3rd group of first round, the 3rd group second take turns, the like;

Cut generating equipment according to taking turns one group, the order of excision is GOOSE trip signal more.

3. micro-electrical network of controlling based on load according to claim 1 is grid-connected arrives from network operation mode switching method, it is characterized in that: in step (4), receiving the inspection isolated island from net order or grid-connected point interface device of higher level's supervisory control system when mode transition controller starts after net order, first calculate the power shortage of micro-operation of power networks, in the time that power shortage is less than the stability margin of energy storage inverter PCS, directly assign from the preset control command of net to energy storage inverter PCS, disconnect and site switch, energy storage inverter PCS transfers V/F mode of operation to through time delay after receiving this order, micro-electrical network is from network operation, when power shortage be greater than energy storage inverter PCS from net stability margin time, excise generating equipment or load according to excision order, make micro-electrical network meet the condition of stable operation, assign from the preset control command of net to energy storage inverter PCS again, disconnect and site switch, energy storage inverter PCS transfers V/F mode of operation to through time delay after receiving this order, and micro-electrical network is from network operation.

4. micro-electrical network of controlling based on load according to claim 3 is grid-connected arrives from network operation mode switching method, it is characterized in that:

When $|\stackrel{\&CenterDot;}{P}\mathrm{pcs}+\stackrel{\&CenterDot;}{P}\mathrm{pcc}|\&GreaterEqual;\mathrm{KPpcszd}$ Time,

Carry out according to excision order $|\stackrel{\&CenterDot;}{P}\mathrm{pcs}+\stackrel{\&CenterDot;}{P}\mathrm{pcc}|-\left|\stackrel{\&CenterDot;}{P}\mathrm{li}\right|$ Or $|\stackrel{\&CenterDot;}{P}\mathrm{pcs}+\stackrel{\&CenterDot;}{P}\mathrm{pcc}|-\left|\stackrel{\&CenterDot;}{P}\mathrm{pi}\right|,$ And the load of record needs excision or the switch sequence number of generating equipment, until then give each power control or load control unit by GOOSE communication by trip signal multicast, power control or load control unit, according to the GOOSE order excision respective switch of concluding a bargin, make micro-electrical network meet the condition of stable operation;

Wherein be respectively energy storage inverter PCS, grid-connected point interface device on send power, for sending power on each load control unit, for sending power on each power control, for energy storage inverter PCS from network operation stability margin.

5. micro-electrical network of controlling based on load according to claim 4 is grid-connected arrives from network operation mode switching method, it is characterized in that: when $|\stackrel{\&CenterDot;}{P}\mathrm{pcs}+\stackrel{\&CenterDot;}{P}\mathrm{pcc}|\&GreaterEqual;\mathrm{KPpcszd}$ Time, and $\stackrel{\&CenterDot;}{P}\mathrm{pcs}+\stackrel{\&CenterDot;}{P}\mathrm{pcc}>0$ Time, excision generating equipment.

6. micro-electrical network of controlling based on load according to claim 4 is grid-connected arrives from network operation mode switching method, it is characterized in that: when $|\stackrel{\&CenterDot;}{P}\mathrm{pcs}+\stackrel{\&CenterDot;}{P}\mathrm{pcc}|\&GreaterEqual;\mathrm{KPpcszd}$ Time, and $\stackrel{\&CenterDot;}{P}\mathrm{pcs}+\stackrel{\&CenterDot;}{P}\mathrm{pcc}<0$ Time, excision load.