MANAGEMENT OF AN ELECTRICITY PRODUCTION …old.utcluj.ro/download/doctorat/Rezumat_Cristian_Dragos_Dumitru.pdf · exploited or imported, and to reduce greenhouse gas ... Simulation

FACULTY OF ELECTRICAL ENGINEERING

Eng. DUMITRU Cristian Dragoş

ABSTRACT OF PHD THESIS

MANAGEMENT OF AN ELECTRICITY

PRODUCTION AND CONSUMPTION SYSTEM WITH

RENEWABLE SOURCES

PhD. Advisor, Prof. PhD. eng. Mircea CHINDRIŞ

Evaluation commission of PhD thesis: PRESIDENT: - Prof. PhD. eng. Radu CIUPA - dean, Electrical Engineering Faculty,

Technical University of Cluj-Napoca; MEMBERS: - Prof. PhD. eng. Mircea CHINDRIŞ - PhD Advisor, Technical University of Cluj- Napoca;

- Prof. PhD. eng. Nicolae Golovanov - referent, “Politehnica” University of Bucharest;

- Prof. PhD. eng. Dorin Sarchiz - referent, “Petru Maior” University of Târgu Mureş; - As.Prof. Physician Eng. Andrei Cziker - referent, Technical University of Cluj-Napoca.

________________________ 2011 __________________________

CONTENT Introduction......................................................................................................................................11 1. Renewable energy sources...........................................................................................................15

1.1. RES types used in electricity production.........................................................................15 1.1.1. Solar energy......................................................................................................17 1.1.2. Wind energy.... .................................................................................................21 1.1.3. Hydraulic energy..... .........................................................................................26 1.1.4. Biomass energy.................................................................................................30

1.2. Legislation and energy policies concerning RES............................................................34 1.3. RES influence on the electric power distribution systems .............................................36

1.3.1. Influence on voltage profile..............................................................................39 1.3.2. Faults or short circuits.......................................................................................40 1.3.3. Influence on power quality...............................................................................42 1.3.4. Connection costs...............................................................................................42

2. Electricity availability from RES................................................................................................45 2.1. RES influence on hybrid system......................................................................................45

2.1.1. Solar radiation influence...................................................................................46 2.1.2. Wind speed influence........................................................................................48 2.1.3. Hydropower parameters influence....................................................................51

2.2. Accumulators and consumers influence on hybrid system............................................. 51 2.2.1. Accumulators influence....................................................................................51 2.2.2. Consumers type and profile influence..............................................................52

2.3. Theoretical model based on RES.....................................................................................54 2.3.1. Photovoltaic cells and panels modeling............................................................54 2.3.2. Wind turbine modeling.....................................................................................60 2.3.3. Hydropower turbine modeling..........................................................................65 2.3.4. Accumulators modeling....................................................................................67 2.3.5. Hybrid system modeling...................................................................................72

2.4. Study of the hybrid system using the developed Matlab theoretical model....................74 2.4.1. Short presentation of the RegenSim-Matlab library.........................................74 2.4.2. Case study for available RES on Mureş valley.................................................78

2.5. Study of the hybrid system using HOMER specialized software....................................84 2.5.1. HOMER. Short introduction ............................................................................84 2.5.2. Case study for available RES on Mureş valley.................................................86

3. Energy management systems for a RES using consumer........................................................ 91 3.1. The necesity and role of energy management systems………………............................92 3.2. Current development of energy management systems....................................................94 3.3. Structure of energy management systems.......................................................................96

3.3.1. Functional levels of energy management systems............................................97 3.3.2. Decision levels of energy management systems...............................................98

3.4. The necesity of monitoring and automatic control in power systems.............................99 3.5. Architecture of monitoring and automatic control for RES based hybrid systems ......101

3.5.1. Local design of monitoring and automatic control systems...........................103 3.5.2. Central design of monitoring and automatic control systems.........................107

4. Power supply management for a small consumer...................................................................111 4.1. Hardware implementation of monitoring and automatic control of a RES based hybrid system........................................................................................................................113

4.1.1. Control logic and hardware structure of power generation system.............. 113 4.1.2. Hardware structure of monitoring system.......................................................120

4.1.3. The system's hardware implementation .........................................................121 4.2. Software implementation of monitoring and automatic control of a RES based hybrid system........................................................................................................................123

4.2.1. Field equipment implementation....................................................................123 4.2.2. Local implementation using virtual instrumentation........... ..........................127 4.2.3. Central implementation using CitectScada.....................................................130

5. Conclusions, contributions and expectations...........................................................................137 5.1. Conclusions....................................................................................................................137 5.2. Contributions.................................................................................................................139 5.3. Further developments....................................................................................................141

References.......................................................................................................................................143 Annex...............................................................................................................................................151

1. Biomass types and energy conversion technologies.........................................................151 2. Table of ideal Pelton/Turgo turbines running speeds.......................................................152 3. Electronic metering scheme..............................................................................................153 4. Electronic scheme incorporating microelectronic modules (microcontroller, radio module, LCD) for power generation system...................................154 5. Electronic scheme of monitoring system..........................................................................155 6. Graphic variation of solar radiation in the area of Târgu Mureş......................................156 7. Code sequence for Scada functions (opening and closing of communication port, data acquisition, etc.)............................................................................................................160

Introduction

Energy production from renewable sources offers significant benefits compared to production from conventional sources. Renewable energy sources (RES) have a much higher degree of availability and are considered very important to improve power supply security by reducing dependence on fossil fuels to be exploited or imported, and to reduce greenhouse gas emissions [Chi08].

The accumulation of the advantages of RES-based systems require the need to introduce advanced methods of control, energy management and monitoring systems to ensure power quality and increase economic efficiency in electricity production and distribution. The introduction of these methods can actually translate into the need to implement a management system which is to ensure a proper management of the energy system.

Based on the above considerations, this paper aims to explore the possibilities of developing and implementing a management for a RES based production and consumption electric energy system. In fulfilling the above mentioned purpose the following objectives were developed: (1) the study of the main types of RES used to produce electricity in Romania, (2) determining the influence of RES variation on electricity production, (3) determining RES mathematical models for the purpose of modeling a hybrid system (4) monitoring energy flows between the hybrid system and electricity supply local network, (5) designing and implementing a hierarchical management system functioning both at hardware and software levels.

Theoretical model of an SRE based system

The modeling of the hybrid system is performed based on the real functioning study of the three types of RES. This study led to the development of a few implemented mathematical models that were also individually simulated. The next step was the development of a hybrid system by interconnecting blocks made on the basis of mathematical models. The modeling, the implementation and the operation simulation of RES hybrid system were carried out in Matlab / Simulink.

In order to allow the modeling, the simulation and the analysis of a wide variety of systems based on RES and the management of these systems, the Matlab software has been expanded by adding the RegenSim library. The above mentioned library has been designed to allow the operation of the above mentioned functions for hybrid systems based on RES; it was also designed interfacing its own components with components from other libraries, especially those of SimPowerSystems.

The basic components of RegenSim library are: wind group (grup eolian), photoelectric solar panel

(panou solar fotoelectric), accumulator (baterie de acumulatoare). The hybrid system simulation model shown in Figure 1 was made by linking the RES sources’ simulation models. Regardless of the number and type of the interconnected sources and given the fact that the energy of these sources is intermittent, it is necessary to connect accumulators for storing energy produced in these hybrid systems.

Study of the hybrid system using HOMER

specialized software The HOMER software is essentially an

economical model that uses inputs to simulate different system configurations, or combinations of components, and generates results that you can view as a list of feasible configurations sorted by net present cost. HOMER also displays simulation results in a wide variety of tables and graphs that help you compare configurations and evaluate them on their economic and technical merits. You can export the tables and graphs for use in reports and presentations [Nre05]. An example of small power system modeled by HOMER is shown in Figure 2.

Figure 2. Hybrid modeled system configuration

Energy management systems for a RES using

consumer

Energy management has emerged as a result of the adoption of energy policies, but also as a result of the ongoing development of technologies, of the possibilities for measurement, analysis and interpretation of results and of the opportunities to react quickly on the power systems elements in order to connect and rehabilitate them.

Figure 1. Simulation model of a RES based hybrid system implemented in Matlab-Simulink environment [Dum10]

Currently, in Romania, integrated

management systems for monitoring and control of power systems are rarely used and standardized, while the distributed systems of electricity generation are in an early stage of development and only work in local experimental networks or in networks with distinct functions of production or consumption of energy.

In energy systems based on RES and DG it is necessary to implement intelligent energy management systems in order to ensure continuous coverage and consumer energy demand, in terms of safety power supply and in a most economical and environmentally friendly manner. The main functions of such a systems are:

- monitoring and control of the main electrical and non-electrical parameters;

- energy quality and control; - the dispatching of the RES production.

The principles and functions of an intelligent energy management system can be summarized as shown in Figure 3.

Architecture of monitoring and automatic control

for RES based hybrid systems

Despite the fact that RES based hybrid production systems offer several advantages not neglectabile in terms of environmental protection and more, these can become difficultly managed structures.

The complexity of hybrid systems requires the implementation of monitoring and automated control systems due to the still significant variation of both electrical and non-electrical parameters of the hybrid system and devices, mainly caused by time fluctuation of the primary energy source. On the other hand, the need to implement a monitoring and automatic control system is given by the nature of the consumer and its load curve.

Figure 3. Energy management system. Principles and functions.[Win01]

Regardless of the field for which they were designed, the monitoring and automated control systems are based mainly on five components: monitoring, sensors and transducers, digital conversion blocks, processing and control and user interface.

Figure 4 shows the structure of a monitoring and numerical control system which includes a numerical controller (computer or microcomputer) acting as a part of a loop-control command. For this digital controller to be compatible with the numerical continuous controlled process, in the system’s structure is included a numerical CAN converter, which converts the measured parameter y(t) into a digital signal y(k)=yk, sampling at times defined by clock synchronization.

Power supply management for a small consumer

The hybrid system’s for the production and

consumption of electricity from RES architecture is proposed in Figure 5. Within the system were provided

solar photoelectric panels, small hydro power and wind groups as RES, accumulators as energy storage devices, electrical connection to the local network as backup power or cutting power and two types of consumers (DC and AC).

Schematic diagram of the management system when using a single RES based energy group is shown in Figure 6. In the block diagram in Figure 6, the microcontrollers (µC) are the main element of the monitoring and control. They receive electrical signals from the RES measuring parameters equipment and from the measuring circuits, which are then processed in order to implement control logic.

The E / R blocks are radio modules that allow remote data transmission and reception and are equipped with digital interfaces to connect with microcontrollers. To ensure the possibility of viewing the values of sent parameters, the system is equipped with LCD displays connected to microcontrollers that allow an opportunity to monitor on-site the electrical and non-electrical system’s parameters.

Figure 4. The monitoring and automated control systems structure

Figure 5. Structure of a hybrid system developed for power supply of a small consumer [Dum407]

Figure 6. Schematic diagram of the management system when using a single RES based energy group

The system’s hardware implementation The studied hybrid system based on RES

consists of three generating units: a group of photoelectric solar panels, a wind group and a microhydroelectric group that debits on a 48 V DC busbar. Also at this busbar are connected accumulators and backup power represented by the local power grid (Figure 7).

Each of the hybrid system’s component groups is equipped with its own microcontroller, which is connected by radio link with a central

microcontroller through broadcasting reception module E / R.

By using signals from measuring blocks, the microcontrollers calculate each group’s generated power and also assures the signals processing from the electrical and non-electrical parameters transducers, monitored in each group.

The numerical values of monitored parameters can be read locally on the LCD displays type of each machine or centrally within the monitoring system.

Figure 7. General architecture of the RES hybrid based monitoring and automatic control system

Figure 8. SCADA implementation scheme of a RES system

Central implementation using CitectScada

The hybrid system’s implementation

schematic diagram includes blocks generators (wind, hydro, photoelectric panels), accumullators, power conversion blocks, consumers and the local network as shown in Figure 8. Measuring blocks of generated and consumed power and also the voltage converter’s measuring block at the consumer can be seen.

Personal contributions

The main author contributions are: - RES availability in Romania and Mureş County; - mathematical simulation and implementation of an

original library named RegenSim in Matlab/Simulink environment;

- identification of the RES parameters based on which energy convertors are modelled;

- RES based energy convertors models: wind group (Grup eolian), solar photoelectric panel (Panou solar fotoelectric), hydroelectric group (Grup hidroenergetic);

- energy storage characteristic models: accumulator (Baterii de acumulatoare);

- developing a RES based complex model of a hybrid system in Matlab/Simulink environment;

- developing simulations for monitoring of RES and consumers’ electrical pararameters;

- the study of the energy parameters of a HOMER based hybrid system;

- the development and implementation of a monitoring and automatic control architecture for a RES based hybrid system;

- implementation of a three-level monitoring system: - local level: field equipment (LCD); - remote level (radio+LCD+CVI PC application); - central level (SCADA).

- the use of microcontrollers for local control; - development and implementation of control logic by

microcontrollers;

- software implementation of a monitoring system at local and central level by using SCADA.

Selected references [Chi08] Chindriş, M., Cziker, A., Miron, A.,

Conectarea la reţea a generatoarelor distribuite. Legislaţia din România, în: Forumul Naţional al Energiei – Foren 2008, 15-19 iun. 2008, Neptun, România, on CD.

[Nre05] National Renewable Energy Laboratory, Getting Started Guide for HOMER Version 2.1, April 2005;

[Dum10] Dumitru, C.D. and Gligor, A., Modeling and Simulation of Renewable Hybrid Power System Using Matlab/Simulink Environment, în: Scientific Bulletin of the „Petru Maior” University of Târgu Mureş, Vol. 7 (XXIV), no. 2, pp. 5-9, România, 2010;

[Win01] Winkler, G., et. al., Intelligent Energy Management of Electrical Power Systems with Distributed Feeding on the Basis of Forecasts of Demand and Generation, in CIRED2001, Conference Publication No. 482;

[Dum407] Dumitru, C.D., The Development of Local DC and AC Distribution Networks Supplied with Energy Provided by Renewable Resources, în: Conferinţa de Inginerie Energetică CIE 2007, 7-8 iunie 2007, Oradea, România, pp. 259-262;

[Mpl11] ***, MPLAB® IDE User’s Guide with MPLAB Editor and MPLAB SIM Simulator, http://ww1.microchip.com/downloads/en/DeviceDoc/MPLAB User_Guide_51519c.pdf ;

[Kal07] Kaltschmitt, M., Streicher, W., Wiese, A., Renewable Energy, Technology, Economics and Environment, Springer-Verlag, Berlin Heidelberg, 2007;

[Gol07] Golovanov, N., Postolache, P., Toader, C., Eficienţa şi calitatea energiei electrice, Ed. AGIR, Bucureşti, Romania, 2007;