On traditional ships, the power system and the power system are relatively independent. The power system is usually composed of conventional heat engine and other mechanical devices. The power system is generally used as an auxiliary energy source and has no direct relationship with ship propulsion.
With the development of technology, the concept of integrated power system (IPS) has also been proposed. Ship IPS combines two independent power and power systems in traditional ships into one, and uniformly supplies power to the propulsion load, pulse load, communication, navigation and daily equipment of ship in the form of electricity, realizing the comprehensive utilization of energy for the entire ship. The ultimate development goal of ship IPS is to ensure the efficient, safe and reliable operation of the entire ship's power system, thereby enhancing the combat effectiveness and vitality of the ship's mobile combat platform.
typical diagram of ship integrated power system
What are the advantages of ship IPS
Using ship integrated power system has the following advantages:
1, increases stealth. Using electric propulsion, the gearbox, clutch and other mechanical transmission devices between the power unit and the thruster can be eliminated, and various driving devices are replaced by electric vehicles. Many pipelines are replaced by cables. The prime mover generator set can be packed with floating rafts to achieve vibration and sound insulation.
US military develops a new type of ship-based integrated high-energy laser weapon
For submarine , the best stealth effect is the prerequisite for it to play a role! How to reduce noise and better stealth performance depends on the power system. However, it is equipped with an integrated power system. Since the propulsion reduction gear device and adjustable pitch propeller can be used, the axis system is shorter. Therefore, the submarine weapons and equipment have greater flexibility in layout, while also reducing the internal noise of the submarine and improving the stealth of the submarine.
2, is conducive to the application of high-energy weapons, and new future concept weapons of , such as directional energy weapon (laser, high-power microwave , particle beam , etc.), kinetic energy weapon ( electromagnetic gun , electric heat gun , missile interceptor, etc.), all require ships to provide excessive load of electrical energy, or even high energy density pulse power supply . The power supply and power system on ships today are separated from the power propulsion system, and energy cannot be used interchangeably, which creates a contradiction in energy planning. IPS not only ensures sufficient power during propulsion, but also provides high-energy power in combat state. The integrated system of
3, power and propulsion is convenient to achieve modularity. The layout of the power device is flexible, reorganized, and mobility. The reliability, maintainability and usability of electrical equipment are much higher than that of mechanical equipment, and have good guaranteeability and strong vitality.
4. The integrated power system can realize centralized control of power distribution between propulsion and ship-based weapon systems, especially the power supply mode of the ring grid plus the regional distribution system , providing a physical way to rationally flow of electricity, which is very beneficial to further improve the reliability of ship-based weapons and equipment. It provides a larger range of options for ship combat use, and enhances survivability and combat effectiveness in high-threat environments
5 and to improve power density. The large ship energy-consuming users uniformly use electricity, reduce and simplify the number of equipment, so that the energy and power load per unit volume and weight of the ship can be maximized, and the space and weight occupy the smallest. Since power can be transferred between all electrical loads, the potential for energy application is most fully realized. While achieving the electrification of the entire ship, it will inevitably realize the automation of operation and control intelligence, bringing the effects of reducing people and increasing efficiency, simplifying logistics, reducing costs and saving life costs.
The development of foreign ship IPS
The research on integrated power system is a huge project, involving various branches and majors of power engineering, such as prime movers, generators, motors , speed regulation, power electronics technology , power management, etc. The development of various equipment in many different professions should be coordinated with similar functions and consistent interfaces. In order to meet the needs of the system and the overall, comprehensive, systematic and in-depth research is required to put forward requirements for each subsystem, so it is difficult.
As early as the 1980s, European and American powers began to explore IPS theory and study key technology. The US Navy established a comprehensive electric power drive plan in 1980, hoping to further improve the performance of warships by combining the daily power system of ships and the propulsion power system.
After 1990, the U.S. Navy turned its attention to improving the purchasing power of ships and turned its research plan to an integrated power system project. The United States confirmed that electric propulsion will be the propulsion power of the next generation of main warships, an important way for new combat ships to enhance combat effectiveness, and the basis of the maritime revolution. Therefore, it was decided that a series of ships such as the developing CVN-21 nuclear aircraft carrier, DD (X) destroyer, CG (X) cruiser, etc., will adopt electric propulsion. The United States will use its new fully electrified ships to configure optimized kinetic and non-kinetic weapons such as active counter-defense systems, free electronic laser missile defense systems, and electromagnetic guns to form a naval transformation force.
By the 21st century, the European and American navies have realized the engineering application of medium-voltage AC integrated power system. The British Type 45 destroyer, which entered service in July 2009, is the world's first surface main battleship using medium-voltage AC integrated power system.
integrated power system has become the basic design solution for US Navy to solve the propulsion and power of various surface ships in the future, and all-electric ships have become a new trend in ship development. In 2007, the United States proposed the technical route of "medium voltage industrial frequency alternating current-medium voltage intermediate frequency alternating current-medium voltage DC". In 2008, the United Kingdom proposed the technical route of "medium voltage industrial frequency alternating current-medium voltage DC".
At present, the United States and the United Kingdom are still developing and adopting medium-voltage AC integrated power systems. The British CVF aircraft carrier, the US DDG1000 destroyer , and the French "Northwest Wind" class amphibious assault ship all use medium-voltage AC integrated power systems.
Medium voltage AC integrated power system has defects
However, although the technology of medium voltage AC integrated power system is mature, it has many defects.
alternating current will definitely generate an induced magnetic field. warship is only so big. Various precision instruments are very compact. The electromagnetic interference caused by AC transmission cannot be ignored. In comparison, the stable DC transmission does not need to consider these issues at all.
In addition, the AC power grid needs to control the amplitude, frequency and phase when running, while the DC power grid only needs to control the amplitude of the voltage, and there is no problem of frequency stability/ reactive power . The operation mode is more flexible, the power supply reliability is higher, and it can withstand higher power fluctuations.
In addition, the medium voltage alternating current route, compared with the medium voltage DC solution, there are more huge equipment such as inverter , and the entire design becomes more complex . The Zumwalter-class ship No. 1 had to be towed back to the shipyard to cut the hole in the ship for maintenance because one of the 12 propulsion motor drive systems failed. During the first sea trial, the ship No. 2 was also unable to continue the subsequent test because the power supply system was unable to continue the subsequent test, so it was forced to return to the factory for repair.
UK GVF aircraft carrier
Take the electromagnetic catapult of the US Ford-class aircraft carrier as an example. Because of the medium-voltage AC technology solution, the failure rate of Ford-class aircraft carrier is high. Among the 8157 ejections, the average failure period (MCBOMF) is 272 times, which means that an average failure occurs every 272 ejections. The failure probability of the Ford-class aircraft carrier electromagnetic catapult design was 1/4000. From 2010 to 2018, more than 700 formal ejections of fighter jets were conducted, and 10 serious failures were encountered. Other problems caused by aircraft carrier often broke out.
Advantages of China's medium voltage DC integrated power system
So, in order to catch up with the United States in this core technology, Academician Ma Weiming spent a full 20 years to finally develop the latest generation of medium voltage DC integrated power system, and China has become the first country in the world to realize medium voltage DC integrated power system on ships.This technical level has surpassed foreign countries for at least 10 years. Compared with medium voltage AC, the medium voltage DC integrated power system breaks through the system frequency limit, reduces the requirements for prime mover speed regulation characteristics, greatly reduces the equipment volume and weight, improves system efficiency and power supply continuity, and realizes a revolutionary transformation from traditional mechanical methods to all-electric methods in my country.
ship medium voltage DC integrated power propulsion system has become the future development direction of ship comprehensive power propulsion system with its advantages such as high power density, high operating efficiency, and high operating flexibility.
At present, the world's comprehensive ship power system has developed to the second generation. Zumwalter-class , 45, Elizabeth-class warships adopt the first generation of integrated power systems, realizing the engineering application of AC integrated power systems. The ship's medium-voltage DC integrated power system successfully developed by Academician Ma Weiming's team belongs to the second generation. CCTV and Military Daily evaluated it as: it was successfully developed and implemented for the first time in the world.
Academician Ma Weiming once said: "The United States is currently in medium-voltage exchange, and it is still at the first generation level, which is one generation behind us. (They are currently) just starting to do pre-research medium-voltage DC. It will be at least ten years later to catch up with us. (A technology) Whether it is leading or not, it is not what I say about whether it is advanced or not. It requires world peers to evaluate it, and the standards exist objectively."
China's electromagnetic catapult technology has no problems such as Ford-class aircraft carriers because of the medium-voltage DC technology, and the reliability and security are greatly improved.
In addition to military purposes, the medium-voltage DC integrated power system will also be used in the military and civilian general technology fields such as fully electrified special vehicles, multi-electric aircraft, rail transit, and new energy power generation in the future. Promote social and economic development.
At present, Academician Ma Weiming is practicing his concept of "all-around ship". When Academician Ma Weiming imagined an all-around ship, he hoped to design a warship that could "unlimited firepower", using the electromagnetic launch system, the strike range is ultra-wide and super wide, and the firepower channels are numerous, replacing the aircraft carrier formation, and even eliminating the aircraft carrier formation.
