By: Dr Alexander Kovalev, Fortum Service, Russia
Modern power systems demand that equipment be highly efficient and reliable. Generating companies that operate in the open electricity market promise to create conditions that enable equipment to operate reliably in combination with the thermodynamic cycles of electricity generation.
Continuous development of operational methods in power plants is the key to creating ideas that will prove successful in a market that is highly competitive. Maintenance that aims to improve reliability (reliability-centred maintenance) and maintenance based on automatic condition monitoring (condition-based maintenance) are providing generating companies with new tools with which to optimize operating conditions in the market.
Basic characteristics of a thermal power plant using remote monitoring
Management of the knowledge base, i.e. the creation, processing and interchange of information and experience, is one of the major resources that the new generation of power companies have. One strategy is to ensure that power plant personnel co-operate effectively with highly skilled experts in the remote support and optimization of power plant operations.
This kind of interaction allows any problem at a power plant to be revealed quickly and harmonized with the basic strategic task of power plant management. Furthermore, systematic condition monitoring and automatic condition control software are valuable tools that can help power plant owners and managers achieve their basic aim, namely high reliability of the plant and output with minimum operation and maintenance costs.
It is well known that manufacturers of power equipment were the pioneers in remote operation support. In particular, GE has developed several technologies for the monitoring of equipment. GE’s programme of remote monitoring and diagnosis of the most complex type of power generation equipment – high-capacity gas turbines – is considered to be particularly successful.
This system allows GE’s experts to obtain operational data remotely on gas turbine plants operating worldwide and to apply algorithms that allow the experts to discover when plant operating conditions become irregular. Having direct access to information on design, operation and maintenance of turbines, GE’s experts are able to quickly define and trace typical operational indications that can signify potential problems. This gives operational personnel in power plants timely information with which to solve problems in the minimum of time with minimal economic damage to power plant owners.
Today, many leading power equipment manufacturers, such as Siemens of Germany and Japan’s Mitsubishi run remote monitoring and support centres. Moreover, this type of monitoring, which was until only recently considered the privilege of leading global manufacturers of power equipment, is becoming the norm, one for which many valid international standards have been developed or are being developed.
Manufacturers use remote diagnostics to pursue a specific goal: to increase the operational reliability of their products. But power companies in general use equipment in their power plants that is made by various manufacturers. Therefore modern power companies often prefer to create their own remote monitoring and support centres for their power plants. Therefore the tasks of such monitoring centres are slightly different, and they are aimed to improve operation of all power plants equipment, independently of the manufacturer.
Expectations are that efficiency and condition monitoring will decrease costs because of the resulting increased reliability of equipment and its operation. The information received from automatic condition control is used to direct timely repair work towards those units that demand maintenance. This reduces the risk of additional breakdowns. Remote support reveals in good time any slowly developing damage and helps to make decision-making more efficient. The use of a local database together with a technical and expert database allows power companies to make accurate, well-planned and economically sound decisions that are based on all the data that is available.
These ideas are realized in a concept developed by Fortum called ‘totally optimized performance’ (TOP). This aims to let the power plant owner get maximum profit over the plant’s period of operation. The main element of the concept concerns the connection of the power plant via a network to a common remote monitoring centre, as is the case in Keilaniemi in Espoo, Finland.
A common remote monitoring centre here gives power plants access to advanced remote monitoring with the optimization of functions. Remote control and analysis usually concerns three of the basic operational characteristics of the power plant – its thermal characteristics, the technical condition of the power plant and control of water chemistry
Thus, the basic thermal equipment of a power plant (turbine, generators and boilers), pipelines and basic auxiliary units (heat exchangers and pumps), substation elements and outdoor switchgear are constantly subject to condition monitoring and condition analysis The most important task of technical condition monitoring is to ensure the operational reliability of the power plant.
Remote monitoring of the power plant’s thermal characteristics helps ensure the plant is economically efficient and optimizes its operating modes under conditions of generation and delivery of electricity and heat to consumers. In particular, remote monitoring maintains the optimum fuel rate for the set mode of delivery to consumers. It also optimizes the structure of the operating equipment in the given mode, which minimizes harmful emissions, etc.
Fortum’s remote support and expert network services are provided to most of Fortum’s power plants in Finland and also to the some power plants in Scotland, Germany, Indonesia, Malaysia and Abu Dhabi.
The basic purpose of TOP is to create the right environment for effective interaction between the power plant’s personnel and the supplementary resources of highly skilled and specialized experts so that joint problem solving can occur. The remote support system includes modules at the power plant for basic data gathering, a telecommunication network for data transmission and intelligent modules in the remote monitoring centre that experts use to provide analysis and decision-making support. The latest information and telecommunication technologies provide the tools and infrastructure for such services.
When diagnosing malfunctions, remote support allows interaction between experts and power plant personnel in real time using real data. The type of communication lines used will vary from traditional telephone lines to optical fibre links and subscriber satellite channels depending on their technical and economic feasibility.
Russian power companies keep qualified personnel at power plants, unlike their Western counterparts, who use their personnel resources more rationally. Systems such as remote monitoring centres are created to provide high quality support by highly paid experts who are located in the remote support centres, to the operating personnel in power plants. As systems are centralized, they can become complex and expensive.
However, the cost of these systems per power plant remains low, even after taking into account the travel expenses of the expert personnel. Moreover, using the centralized system, it is easier to collect statistics and operational experience from one or more power plants to solve similar problems at other power plants.
The analysis of the overall performance of a power plant and of the technical condition of its equipment is based on the analysis of changes in the power plant’s characteristics in real time – in other words on the basis of a trends analysis of basic characteristics. The efficiency of the technique used to reveal slowly developing defects depends on how well it converts collected data into helpful information. The task of an analytical system is to make the most effective use of all the measurements coming from power plants. This allows failure to be detected in good time, and in the ideal case means that failure can be predicted.
Figure 1: Essentials of an analytical monitoring system
Analytical systems are created using modern information technologies to model intelligent systems. Figure 1 shows the essentials of an analytical system. As an example, we shall view some of the analytical modules used to follow power plant characteristics.
Current economic parameters
Current economic parameters can be followed using the modelling and analytical software that Solvo has developed in Fortum. Solvo-online, a special Fortum modelling software is used for the calculation of thermal output, while the offline version can be used as a simulator of various operational scenarios. Solvo also calculates and follows individual operational parameters, for example in the case of turbines the isoentropic output of the compressor and the circulation parameter. All information is transferred to the centre for diagnostics where the data are periodically analyzed.
Calculations made with Solvo are based on energy balance data and the specific equations that describe functions and the current operation of individual pieces of equipment. In on-line mode, Solvo is a tool to monitor current economy. It also carries out condition monitoring to produce real values for efficiency and values corrected according to ISO standards. This enables Solvo to carry out current condition monitoring using various parameters, adjusted for external conditions. Solvo enables equipment to be subdivided into its components so that, for example, the parameters of the separate parts of boiler equipment – those of the evaporator, the super heater and the waste gas heater- can be followed individually.
The levels and range of vibration are measured directly at the power plant using both portable and fixed measuring equipment. Information is transferred to the remote support control centre where experts analysis it using decision-making support systems. When a power plant has a fixed measuring system, constant monitoring from the remote support centre is possible. However, analyzes are more commonly carried out periodically, so regular reports with recommendations on operation are given to the power plant personnel.
The closed production process control systems are monitored constantly using selective condition indicators. Using the received data, experts in the remote support centre can adjust and optimize control parameters.
Equipment at the power plant analyses water chemistry, and these measurements are monitored by an analysis system at the power plant and by experts at the remote support centre. In cases in which deviations from norm are revealed, the support system recommends what corrections should be made, and the experts will check and confirm the result.
Measure of success
The real measure of success of the remote monitoring system is defined not simply by the development and introduction of technical solutions and systems, but by the work of the team of power plant personnel and experts at the remote support centre. The work uses the know-how and experience of both.
To estimate the practical advantages of remote support, a review follows of a typical example of monitoring, i.e. vibration monitoring of a gas turbine’s blades. Figure 2 highlights the case in which an abrupt change in the vibration parameters of a gas turbine’s blades has been noticed. The change was small, and the amplitude of vibration remained insignificant even after failure, so there was no emergency at the power plant. The change nevertheless had been noted during the regular check made by experts in the remote support centre within the framework of the contract on vibration monitoring.
Figure 2: An abrupt change in vibration parameters of the blades of a gas turbine are clear
Examination showed that the abrupt change of parameters was observed by most of the vibration transducers. The character of amplitude change indicated that the cause was a sudden increase in imbalance. The most probable explanation of such a failure is a break in a turbine blade.
After analysis of the situation by vibration experts, the power plant personnel decided to carry out an endoscopic inspection of the machine when it was not in use. This inspection confirmed that there was a break in the blade. Timely elimination of technical malfunctions and the prevention of equipment stoppages and emergencies not only increase the reliability of power plants, they also provide appreciable economic benefits, the amount of benefit depending on many factors.
Ideal for the Russian market
Modern automation and control systems for equipment in electricity generation provide ever more data to make the work of operating personnel in power plants successful and effective. This in turn makes the work of the generating company as a whole successful in a competitive electricity market. However, today there is the problem of the shortage of qualified personnel for power plants, a problem, which becomes more serious every year, making the training of skilled personnel more expensive and more difficult. This is a problem faced today by power companies in the West, and which will in the near future also be faced by Russia.
Fortum is using its wide experience and know-how in the technology of remote support to establish a remote monitoring centre in St Petersburg, Russia, to meet the needs of Russian electricity generating companies. Fortum plans to ensure that the Russian remote support centre’s recommendations to power plants are adapted to national norms, standards and requirements of Russian power plants.
At the same time, this centre will be integrated into Fortum’s global remote support network and will make use of all of the experience, which has accumulated in the operation of power plants worldwide. The basic structure of the Russian remote support centre is shown in Figure 3.
Figure 3: Basic structure of the Russian remote support centre
The rapid development of an open power market in Russia is creating a market for such a centre. In the exceptional and daily optimal operation of power plants, operating personnel may need additional support. In our opinion, one of the most effective ways to solve this problem for power companies is to use a remote support centre in which highly skilled specialists are based and can provide on-line assistance for the operation personal of power plants.
It is clear that the implementation of the technologies of remote support will require modernization of the automatic control system at a power plant, the building of an extensive communication network, and the adjustment of modern methods and know-how for effective interaction between experts at the centre and power plant personnel. All that is needed is investment, and international experience shows that financial benefits are immeasurably higher than costs.
Today’s task is to combine innovative technologies with the knowledge and skills of the most skilled experts to increase the productivity and reliability of power plant operation in a market economy.