CN106345752B - A kind of double four-rotor helicopter photovoltaic laser wiping board systems - Google Patents

A kind of double four-rotor helicopter photovoltaic laser wiping board systems Download PDF

Info

Publication number
CN106345752B
CN106345752B CN201610701712.5A CN201610701712A CN106345752B CN 106345752 B CN106345752 B CN 106345752B CN 201610701712 A CN201610701712 A CN 201610701712A CN 106345752 B CN106345752 B CN 106345752B
Authority
CN
China
Prior art keywords
laser
double
rotor
air
swab
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CN201610701712.5A
Other languages
Chinese (zh)
Other versions
CN106345752A (en
Inventor
王春岩
卢青
胡金刚
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cangzhou Dwaya Laser Technology Co Ltd
Original Assignee
Cangzhou Dwaya Laser Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cangzhou Dwaya Laser Technology Co Ltd filed Critical Cangzhou Dwaya Laser Technology Co Ltd
Priority to CN201610701712.5A priority Critical patent/CN106345752B/en
Publication of CN106345752A publication Critical patent/CN106345752A/en
Application granted granted Critical
Publication of CN106345752B publication Critical patent/CN106345752B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B08CLEANING
    • B08BCLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B7/00Cleaning by methods not provided for in a single other subclass or a single group in this subclass
    • B08B7/0035Cleaning by methods not provided for in a single other subclass or a single group in this subclass by radiant energy, e.g. UV, laser, light beam or the like
    • B08B7/0042Cleaning by methods not provided for in a single other subclass or a single group in this subclass by radiant energy, e.g. UV, laser, light beam or the like by laser
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B08CLEANING
    • B08BCLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B5/00Cleaning by methods involving the use of air flow or gas flow
    • B08B5/02Cleaning by the force of jets, e.g. blowing-out cavities
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B08CLEANING
    • B08BCLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B7/00Cleaning by methods not provided for in a single other subclass or a single group in this subclass
    • B08B7/04Cleaning by methods not provided for in a single other subclass or a single group in this subclass by a combination of operations
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02SGENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/10Cleaning arrangements
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy

Landscapes

  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Couplings Of Light Guides (AREA)

Abstract

The present invention relates to a kind of double four-rotor helicopter photovoltaic laser wiping board systems, including double four-rotor helicopters, laser swab, video camera, double four-rotor helicopters are equipped with laser swab, and double four-rotor helicopter bottoms are equipped with video camera, and top is equipped with GPS antenna;By the image of camera transmissions, it is remotely controlled double four-rotor helicopters and adjusts position, photovoltaic panel is cleaned by laser swab.Advantage is:By double four-rotor helicopters as liter top equipment, scouring purger of the laser swab as photovoltaic panel, video camera is as monitoring device, laser swab, which is carried, using double four-rotor helicopters cleans photovoltaic panel, it is flexible to operation, while image/video can be transmitted at any time by video camera to adjust the foundation for cleaning angle.

Description

A kind of double four-rotor helicopter photovoltaic laser wiping board systems
Technical field
The present invention relates to a kind of photovoltaic laser board brushing machine more particularly to a kind of double four-rotor helicopter photovoltaic laser wiping boards systems System.
Background technology
Economy rapid growth brings the acceleration of the energy to consume, and electricity consumption market is faced with huge pressure.Renewable energy Source generation technology is the important channel for solving the problems, such as power shortages.Wherein, solar energy power generating is renewable energy power generation It is a kind of.
Solar energy power generating is to rely on solar cell module, using the electronics property of semi-conducting material, by luminous energy It is converted into electric energy.And parallel network power generation refers to that will receive the solar radiant energy of coming by solar panel, also referred to as photovoltaic panel Amount becomes high voltage direct current after high-frequency direct-current is converted, same frequently to power grid output and network voltage after inverter inversion, With the simple sinusoidal alternating current of phase.In recent years, have benefited from constantly shouldering wiping being in fast-developing trend, other than large-scale photovoltaic generates electricity, It is used widely in residential households, industrial premises, market supermarket and other fields.
Due to being generated electricity by solar irradiation, photovoltaic panel must be exposed for, and towards sunlight, be bound to fall for a long time dust or Spot, this will influence generating efficiency.Since the photovoltaic generation unit of cell and plant area is to be placed in resident roof or workshop roof, Personnel or large scale equipment are inconvenient to climb to the top of a mountain, and roof place is narrow, it has not been convenient to it operates, so be considered as rising top automatically, and energy It is ideal to photovoltaic panel automatic scrubbing.
Invention content
In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a kind of double four-rotor helicopter photovoltaic laser wiping boards System using double quadrotors as rising top equipment, while cleaning the scouring for realizing photovoltaic panel using laser, can it is automatic, flexibly, Quickly clean photovoltaic panel.
To achieve the above object, the invention is realized by the following technical scheme:
A kind of double four-rotor helicopter photovoltaic laser wiping board systems, including double four-rotor helicopters, laser swab, take the photograph Camera, double four-rotor helicopters are equipped with laser swab, and double four-rotor helicopter bottoms are equipped with video camera, and top is equipped with GPS antenna;By the image of camera transmissions, it is remotely controlled double four-rotor helicopters and adjusts position, cleaned by laser swab Photovoltaic panel.
Double four-rotor helicopters include ontology, laser and control circuit, supply air line, holder, are evenly distributed on ontology It sets there are four wing bar, each wing bar is equipped with one group of rotor, and every group of rotor is upper layer and lower layer wing plate, and every layer is symmetrical Two wing plates;Ontology is connect by laser with control circuit, supply air line and laser swab;Laser swab passes through branch Support axis is fixed on holder;
The laser swab includes air delivering pipeline, laser transmission fiber, fiber orientation cylinder, wrist swing mechanism, wrist Rotating mechanism, arm support, laser air-jet combinatorial head, connection ring, focusing knob, arm support are connected with double four-rotor helicopters, arm Bracket end is connect with wrist swing mechanism, and wrist swing mechanism is connect with wrist rotating mechanism, and laser air-jet combinatorial head passes through connection ring It is connect with wrist rotating mechanism;Laser air-jet combinatorial overhead is equipped with fiber orientation cylinder, to limit the position of laser transmission fiber, Laser air-jet combinatorial head bottom is connected with laser head shell, and laser air-jet combinatorial head outer wall is equipped with focusing knob;Air delivering pipeline, laser One end of Transmission Fibers is connect with laser air-jet combinatorial head, the supply air line phase of the air delivering pipeline other end and double four-rotor helicopters Even, the laser of double four-rotor helicopters is connected with control circuit and the laser transmission fiber other end.
The laser air-jet combinatorial head includes laser head shell, gas supply cone cylinder, beam-expanding system, dynamic focusing system, gathers Jiao Jing, interior left gas circuit, interior right gas circuit, laser head shell is interior to be equipped with gas supply cone cylinder, air delivering pipeline and interior left gas circuit, interior right gas circuit phase Even, interior left gas circuit, interior right gas circuit are respectively gas supply cone cylinder gas supply from both sides, and compressed air is sprayed by gas supply cone cylinder end, to Photovoltaic panel is purged, beam-expanding system is connected with laser transmission fiber, and beam-expanding system is connected through dynamic focusing system with focus lamp, focusing Button is adjusting focus lamp position.
Compared with prior art, the beneficial effects of the invention are as follows:
The present invention is set as top equipment, laser swab is risen as the scouring purging of photovoltaic panel by double four-rotor helicopters Standby, video camera carries laser swab as monitoring device, using double four-rotor helicopters and cleans photovoltaic panel, easy to operate spirit It is living, while image/video can be transmitted at any time by video camera to adjust the foundation for cleaning angle, specific advantage is:
1) present invention using double four-rotor helicopters carry cleaning devices to the photovoltaic panel on resident roof or workshop roof into Row cleaning, this is one can rise top automatically, and can be an ideal innovation scheme to photovoltaic panel automatic scrubbing;
2) present invention using double four-rotor helicopters carry optical fiber lasers clean and compressed air soot-blowing device, it can be achieved that The fast automatic cleaning of photovoltaic panel, this by be the fast automatic cleaning of photovoltaic panel a technological innovation;
3) present invention regards monitoring and ground remote control helicopter by video camera, realizes that comprehensive cleaning regards;
4) present invention realizes remotely monitor by GPRS/LTE (3G/4G) mobile Internet.
Description of the drawings
Fig. 1 is the structural schematic diagram of the present invention.
Fig. 2 is laser air-jet combinatorial head internal structure schematic diagram.
Fig. 3 is laser swab structural schematic diagram.
Fig. 4 is Control system architecture block diagram.
Fig. 5 is the structure diagram of GPRS/LTE monitoring units.
In figure:1- wrist rotating mechanism 2- air delivering pipeline 3- laser transmission fiber 4- fiber orientation cylinder 5- wrist swing mechanisms 6- arm supports
Left gas circuit 102-3- in 100- laser air-jet combinatorial head 101- connection ring 102-1- laser head shells 102-2- Supply right gas circuit 102-5- laser beams 103- focusing knobs 104- optical path adjusting chamber 104-1- focus lamps in cone cylinder 102-4- 104-2- beam-expanding system 104-3- dynamic focusing systems
The bis- four-rotor helicopter 201- laser of 200- and two layers of wing plate under upper two layers of wing plate 203- of control circuit 202- 204-GPS antenna 205- wing bar 206- holder 207- video camera 208- support shaft 209- supply air lines.
Specific implementation mode
The present invention is described in detail with reference to the accompanying drawings of the specification, it should be noted that the implementation of the present invention is unlimited In the following embodiments and the accompanying drawings.
See that Fig. 1, a kind of double four-rotor helicopter photovoltaic laser wiping board systems, including double four-rotor helicopters, laser are cleaned Device, video camera, double four-rotor helicopters are equipped with laser swab, and double four-rotor helicopter bottoms are equipped with video camera, top Portion is equipped with GPS antenna;By the image of camera transmissions, it is remotely controlled double four-rotor helicopters and adjusts position, cleaned and filled by laser Set scouring photovoltaic panel.
Double four-rotor helicopters include ontology, laser and control circuit, supply air line, holder, are evenly equipped with and are equipped on ontology Four wing bars, each wing bar are equipped with one group of rotor, and every group of rotor is upper layer and lower layer wing plate, and every layer is two symmetrical wings Plate;Ontology is connect by laser with control circuit, supply air line and laser swab;Laser swab is solid by support shaft It is scheduled on holder;Laser generator and compressed air unit are equipped in ontology, for being supplied for laser for laser air-jet combinatorial head.
See that Fig. 2, laser swab include air delivering pipeline, laser transmission fiber, fiber orientation cylinder, wrist swing mechanism, wrist Rotating mechanism, arm support, laser air-jet combinatorial head, connection ring, focusing knob, arm support are connected with double four-rotor helicopters, arm Bracket end is connect with wrist swing mechanism, and wrist swing mechanism is connect with wrist rotating mechanism, and laser air-jet combinatorial head passes through connection ring It is connect with wrist rotating mechanism;Laser air-jet combinatorial overhead is equipped with fiber orientation cylinder, to limit the position of laser transmission fiber, Laser air-jet combinatorial head bottom is connected with laser head shell, and laser air-jet combinatorial head outer wall is equipped with focusing knob;Air delivering pipeline, laser One end of Transmission Fibers is connect with laser air-jet combinatorial head, the supply air line phase of the air delivering pipeline other end and double four-rotor helicopters Even, the laser of double four-rotor helicopters is connected with control circuit and the laser transmission fiber other end.
See that Fig. 3, laser air-jet combinatorial head include laser head shell, gas supply cone cylinder, beam-expanding system, dynamic focusing system, gather Jiao Jing, interior left gas circuit, interior right gas circuit, laser head shell is interior to be equipped with gas supply cone cylinder, air delivering pipeline and interior left gas circuit, interior right gas circuit phase Even, interior left gas circuit, interior right gas circuit are respectively gas supply cone cylinder gas supply from both sides, and compressed air is sprayed by gas supply cone cylinder end, to Photovoltaic panel is purged, beam-expanding system is connected with laser transmission fiber, and beam-expanding system is connected through dynamic focusing system with focus lamp, focusing Button is adjusting focus lamp position.Laser air-jet combinatorial head is internally provided with optical path adjusting chamber, beam-expanding system, dynamic focusing system, Focus lamp is arranged in optical path adjusting intracavitary.
See that Fig. 4, control system include image monitoring unit, flight control system, GPRS/LTE monitoring units, system control Unit, blowing control unit, Laser control unit, pressure regulation unit, flight control system communicate with GPS antenna, flight control System and image monitoring unit, system control unit, GPRS/LTE monitoring units, blowing control unit, Laser control unit phase Connection, system provides 5V, 12V, 48V power supply to pressure regulation unit in order to control.
Image monitoring unit is connected with video camera, and image/video information is shown for handling.Flight control system is used for The flight of the double four-rotor helicopters of control is risen and fallen.GPRS/LTE monitoring units with remote service center for communicating.
See Fig. 5, GPRS/LTE monitoring units include the LCD display being connected with embedded type micro-computer, time circuit, on Reset circuit, power conversion module, USB interface, IP address setup module, GPRS/LTE modules, GPRS/LTE modules and SIM Card is connected.
When work, double four-rotor helicopters of laser swab are carried, the flight control system control of control system is passed through The double four-rotor helicopters of system give rise to photovoltaic panel top, confirm laser air-jet combinatorial by the video image information of camera acquisition The position of head adjusts the position of double four-rotor helicopters by control system, so that laser air-jet combinatorial head is reached and cleans position, leads to Control system control air delivering pipeline and laser transmission fiber are crossed, laser beam and compressed air, band are provided for laser air-jet combinatorial head There is heat laser beam to form buckles to photovoltaic panel at scattering, the wind-force that cooperation gas supply cone cylinder is formed cleans photovoltaic panel. The double four-rotor helicopters of control system control return to ground after cleaning.
The present invention is set as top equipment, laser swab is risen as the scouring purging of photovoltaic panel by double four-rotor helicopters Standby, video camera carries laser swab as monitoring device, using double four-rotor helicopters and cleans photovoltaic panel, easy to operate spirit It is living, while image/video can be transmitted at any time by video camera to adjust the foundation for cleaning angle, specific advantage is:
1) present invention using double four-rotor helicopters carry cleaning devices to the photovoltaic panel on resident roof or workshop roof into Row cleaning, this is one can rise top automatically, and can be an ideal innovation scheme to photovoltaic panel automatic scrubbing;
2) present invention using double four-rotor helicopters carry optical fiber lasers clean and compressed air soot-blowing device, it can be achieved that The fast automatic cleaning of photovoltaic panel, this by be the fast automatic cleaning of photovoltaic panel a technological innovation;
3) present invention regards monitoring and ground remote control helicopter by video camera, realizes that comprehensive cleaning regards;
4) present invention realizes remotely monitor by GPRS/LTE (3G/4G) mobile Internet.

Claims (2)

1. a kind of double four-rotor helicopter photovoltaic laser wiping board systems, including double four-rotor helicopters, laser swab, camera shooting Machine, double four-rotor helicopters are equipped with laser swab, and double four-rotor helicopter bottoms are equipped with video camera, and top is equipped with GPS Antenna;By the image of camera transmissions, it is remotely controlled double four-rotor helicopters and adjusts position, photovoltaic is cleaned by laser swab Plate, which is characterized in that double four-rotor helicopters include ontology, laser and control circuit, supply air line, holder, ontology On be evenly equipped with and set there are four wing bar, each wing bar is equipped with one group of rotor, and every group of rotor is upper layer and lower layer wing plate, and every layer is mutual Symmetrical two wing plates;Ontology is connect by laser with control circuit, supply air line and laser swab;Laser swab It is fixed on holder by support shaft;
The laser swab includes air delivering pipeline, laser transmission fiber, fiber orientation cylinder, wrist swing mechanism, wrist rotation Mechanism, arm support, laser air-jet combinatorial head, connection ring, focusing knob, arm support are connected with double four-rotor helicopters, arm support End is connect with wrist swing mechanism, and wrist swing mechanism is connect with wrist rotating mechanism, and laser air-jet combinatorial head passes through connection ring and wrist Rotating mechanism connects;Laser air-jet combinatorial overhead is equipped with fiber orientation cylinder, to limit the position of laser transmission fiber, laser Air-jet combinatorial head bottom is connected with laser head shell, and laser air-jet combinatorial head outer wall is equipped with focusing knob;Air delivering pipeline, laser transmission One end of optical fiber is connect with laser air-jet combinatorial head, and the air delivering pipeline other end is connected with the supply air line of double four-rotor helicopters, The laser of double four-rotor helicopters is connected with control circuit and the laser transmission fiber other end.
2. a kind of double four-rotor helicopter photovoltaic laser wiping board systems according to claim 1, which is characterized in that described Laser air-jet combinatorial head include laser head shell, gas supply cone cylinder, beam-expanding system, dynamic focusing system, focus lamp, interior left gas circuit, Interior right gas circuit is equipped with gas supply cone cylinder in laser head shell, and air delivering pipeline is connected with interior left gas circuit, interior right gas circuit, interior left gas circuit, interior Right gas circuit is respectively gas supply cone cylinder gas supply from both sides, and compressed air is sprayed by gas supply cone cylinder end, to purge photovoltaic panel, expanded System is connected with laser transmission fiber, and beam-expanding system is connected through dynamic focusing system with focus lamp, and focusing knob focuses to adjust Mirror position.
CN201610701712.5A 2016-08-22 2016-08-22 A kind of double four-rotor helicopter photovoltaic laser wiping board systems Expired - Fee Related CN106345752B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201610701712.5A CN106345752B (en) 2016-08-22 2016-08-22 A kind of double four-rotor helicopter photovoltaic laser wiping board systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201610701712.5A CN106345752B (en) 2016-08-22 2016-08-22 A kind of double four-rotor helicopter photovoltaic laser wiping board systems

Publications (2)

Publication Number Publication Date
CN106345752A CN106345752A (en) 2017-01-25
CN106345752B true CN106345752B (en) 2018-08-07

Family

ID=57844396

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201610701712.5A Expired - Fee Related CN106345752B (en) 2016-08-22 2016-08-22 A kind of double four-rotor helicopter photovoltaic laser wiping board systems

Country Status (1)

Country Link
CN (1) CN106345752B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107399211A (en) * 2017-07-18 2017-11-28 王永成 Use car in land, water and air three
CN115488109A (en) * 2022-10-14 2022-12-20 华能新能源上海发电有限公司 Photovoltaic cell panel cleaning device and method

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6277202B1 (en) * 1997-08-27 2001-08-21 Environmental Surface Technologies Method and apparatus for utilizing a laser-guided gas-embedded pinchlamp device
US6573702B2 (en) * 1997-09-12 2003-06-03 New Wave Research Method and apparatus for cleaning electronic test contacts
US20060138104A1 (en) * 2001-05-25 2006-06-29 Devore Paul W Fuel cell and liquid container sealant removal system
ATE462870T1 (en) * 2004-06-14 2010-04-15 Gas Turbine Efficiency Ab SYSTEM AND DEVICES FOR COLLECTING AND TREATING ENGINE CLEANING WASTEWATER
KR100797787B1 (en) * 2005-06-03 2008-01-24 주식회사 아이엠티 Dry cleaning system using a laser
CN201720218U (en) * 2010-05-25 2011-01-26 北京大学 Laser cleaning system
CN105470858B (en) * 2015-12-10 2017-08-25 国家电网公司 UAV flight's high-energy ray removes wire foreign matter device
CN206046591U (en) * 2016-08-22 2017-03-29 沧州致胜机器人科技有限公司 A kind of pair of four-rotor helicopter photovoltaic laser wiping board system

Also Published As

Publication number Publication date
CN106345752A (en) 2017-01-25

Similar Documents

Publication Publication Date Title
US8487230B2 (en) Intelligent solar energy collection system with a dedicated control device
CN106345752B (en) A kind of double four-rotor helicopter photovoltaic laser wiping board systems
WO2009002168A1 (en) Device for collecting solar energy
CN207559918U (en) A kind of solar photovoltaic generation system
CN110829964A (en) Solar automatic light following device and method based on user mobile equipment positioning
KR20120007249A (en) Solar power generation system for high efficient
CN206046591U (en) A kind of pair of four-rotor helicopter photovoltaic laser wiping board system
CN104917444A (en) Quasi-groove-type dot condensation solar energy utilization device
CN108718820A (en) Solar planting greenhouse based on Internet of Things
CN101237196A (en) Solar light-concentrating laser power generation device
CN207718232U (en) A kind of solar energy photovoltaic generating automatic tracking system complete set of equipments
CN207853798U (en) A kind of wave band radiation energy-storing and power-generating system and array
CN207853799U (en) A kind of parallel network power generation equipment
EP3444539A1 (en) Apparatus for mounting a solar energy device
CN207968403U (en) A kind of equipments of HV transmission lines power supply device
CN218446482U (en) Solar combined heat and power mining device
CN104990284B (en) The hot power generation and heat collection control system of group control solar energy high temperature
CN214930627U (en) Patrol operation unmanned aerial vehicle system for power grid planning
CN208364299U (en) A kind of high efficiency wind-electricity energy storage heat and power supply device
CN221669819U (en) Automatic cleaning device for photovoltaic
CN103822369A (en) Disc type solar energy collector and power generation system
CN105007027A (en) Solar energy based wind-solar power generation system
CN107863920A (en) A kind of wave band radiation energy-storing and power-generating system and array
CN201319573Y (en) Multiple light-gathering solar photovoltaic power generator
WO2019059545A1 (en) Merged/combined power generation system using solar heat and wind power

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20180807

Termination date: 20190822

CF01 Termination of patent right due to non-payment of annual fee