Många elektriska apparater är i behov av reaktiv effekt för att kunna fungera. Transport av reaktiv effekt tar onödig plats av den tillgängliga kapaciteten i elnätet, därför används kondensatorbatterier nära slutanvändaren för att generera reaktiv effekt. Därmed genereras och förbrukas den reaktiva effekten i en avskild del av nätet. Tillkoppling av kondensatorbatterier ger upphov till transienter som kan skada andra närliggande komponenter. Utifrån det verkliga ställverket Stallbacka i Trollhättan har denna rapport analyserat de transienter som uppstår efter tillkoppling av ett kondensatorbatteri inom mellanspänningsområdet. Analysen har innefattat hur stora transienterna blir efter olika förutsättningar och scenarier. Resultatet visade att transienterna i detta fall aldrig nådde upp till några allvarliga nivåer, och därmed klarade komponenterna sig med god marginal. Huruvida transienterna påverkar elkvaliteten är oklart, då det inte finns några definierade krav. Slutligen skulle ett beräkningsverktyg för förutspådda transienter tas fram. Beräkningsverktyget blev aldrig fullständigt på grund av den ohanterliga lösningen som erhölls. / Many electrical devices need reactive power to operate. Transmission of reactive power occupies a proportion of the available capacity in the power system and therefore capacitor banks are used near to the end user to generate reactive power. Thus, the reactive effect is generated and consumed in a separate part of the power system. Capacitor banks switching causes transients which may damage the surrounding components. Based on the real substation Stallbacka in Trollhättan, this study has analysed capacitor banks switching transients within the medium voltage level. The analysis has covered the size of these transients according to different conditions and scenarios. The result showed that the transients in this case never reached serious levels, thus there was no impact on the components. It is not clear whether the transients affect the power quality because there are no defined limits.  A calculation tool to the predicted transients was supposed to be created in the process. This calculation tool was never completed due to the unmanageable solution that was obtained.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2015-12-16T11:21:48Z No. of bitstreams: 1 igordelgadodemelo.pdf: 4931795 bytes, checksum: cf03c45f0f2492c6cf9186af1b3866a2 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2015-12-16T11:57:23Z (GMT) No. of bitstreams: 1 igordelgadodemelo.pdf: 4931795 bytes, checksum: cf03c45f0f2492c6cf9186af1b3866a2 (MD5) / Made available in DSpace on 2015-12-16T11:57:23Z (GMT). No. of bitstreams: 1 igordelgadodemelo.pdf: 4931795 bytes, checksum: cf03c45f0f2492c6cf9186af1b3866a2 (MD5) Previous issue date: 2015-09-18 / Este trabalho objetiva apresentar uma metodologia capaz de estimar os componentes harmônicos em sistemas de distribuição com topologia radial utilizando PMUs (Phasor Measurement Units). Os estados a serem estimados serão as correntes passantes em todas as linhas do sistema em coordenadas retangulares. Uma vez que essas correntes são obtidas, torna-se possível o cálculo de outras grandezas elétricas através das equações de fluxo de potência e leis de Kirchhoff. A metodologia considera poucas unidades de medição fasorial (as PMUs) instaladas efetuando a leitura dos sinais de tensões nodais e correntes nas linhas com distorção harmônica. A fim de restaurar a observabilidade do sistema por completo, são considerados dados históricos de demanda de potência ativa/reativa, os quais serão tratados como restrições de desigualdades excursionando entre um valor mínimo e máximo considerados em um problema de otimização não linear que visa diminuir a diferença entre os valores monitorados pelas PMUs e os calculados pela metodologia. As mencionadas restrições permitem ao estimador o acompanhamento das variações sofridas ao longo do tempo na curva de carga para a frequência fundamental e também para as demais frequências. A abordagem proposta neste trabalho considera a modelagem trifásica de equipamentos e linhas de distribuição, portanto, são modelados os efeitos de acoplamento mútuo entre fases e a operação não linear de equipamentos de eletrônica de potência tiristorizados. O método demonstra eficiência não apenas em estimar os componentes harmônicos de um certo espectro considerado no estudo, como também se mostra uma ferramenta prática de detecção e identificação de fontes harmônicas no sistema elétrico de potência, além de explicitar um exemplo prático do uso de PMUs no que tange ao monitoramento de redes de distribuição, carentes de acompanhamento em tempo real. A metodologia ainda se mostra capaz de ser aliada a grandes estudos contextualizados em qualidade de energia, uma vez que permite a estimação de índices de distorção harmônica. / This work aims to present a methodology which is capable of estimating harmonic components for distribution systems with radial topology, using PMUs (Phasor Measurement Units). The estimated states will be all branch currents of the system expressed in rectangular coordinates. Once these currents are obtained, it is possible to calculate other electrical quantities using power flow equations and also Kirchhoff’s law. The methodology considers the installation of a few number of phasor measurement units which will measure voltage and branch currents signals distorted by harmonic sources. In order to make the whole system observable, historical data of active/reactive power demand will be treated as inequality constraints varying between minimum and maximum limits described in a non linear optimization problem, which aims to minimize the difference between the values monitored by PMUs and the ones calculated by the methodology. The already mentioned constraints allows the accompaniment of the variations occured in a typical load curve during a period of time for the fundamental frequency and also for their multiples, allowing the accompaniment of the harmonic load curve, normally unknown. The proposed approach considers a three-phase modelling of equipments and distribution lines, subject to their mutual coupling effects caused by mutual impedances between the lines. It will also be considered electronic-based devices using thyristors located along the distribution feeder, injecting harmonic currents in the system. The method demonstrates efficiency in estimating the harmonic states of the net and also in detecting and identifying harmonic sources in an eletric power system, besides showing a practical use of PMUs for the monitoring of distribution systems, lacking in information and real-time accompaniment. The method also enables the estimation of power quality indicators such as total harmonic distortion.

Ce travail de thèse propose des approches d’identification et de reconnaissance des harmoniques de courant qui sont basées sur des stratégies d’apprentissage automatique. Les approches proposées s’appliquent directement dans les dispositifs d’amélioration de la qualité de l’énergie électrique.Des structures neuronales complètes, dotées de capacités d’apprentissage automatique, ont été développées pour identifier les composantes harmoniques d’un signal sinusoïdal au sens large et plus spécifiquement d’un courant alternatif perturbé par des charges non linéaires. L’identification des harmoniques a été réalisée avec des réseaux de neurones de type Multi–Layer Perceptron (MLP). Plusieurs schémas d’identification ont été développés, ils sont basés sur un réseau MLP composé de neurones linéaire ou sur plusieurs réseaux MLP avec des apprentissages spécifiques. Les harmoniques d’un signal perturbé sont identifiées avec leur amplitude et leur phase, elles peuvent servir à générer des courants de compensation pour améliorer la forme du courant électrique. D’autres approches neuronales a été développées pour reconnaître les charges. Elles consistent en des réseaux MLP ou SVM (Support Vector Machine) et fonctionnent en tant que classificateurs. Leur apprentissage permet à partir des harmoniques de courant de reconnaître le type de charge non linéaire qui génère des perturbations dans le réseau électrique. Toutes les approches d’identification et de reconnaissance des harmoniques ont été validées par des tests de simulation à l’aide des données expérimentales. Des comparaisons avec d’autres méthodes ont démontré des performances supérieures et une meilleure robustesse. / This thesis proposes identifying approaches and recognition of current harmonics that are based on machine learning strategies. The approaches are applied directly in the quality improvement devices of electric energy and in energy management solutions. Complete neural structures, equipped with automatic learning capabilities have been developed to identify the harmonic components of a sinusoidal signal at large and more specifically an AC disturbed by non–linear loads. The harmonic identification is performed with multilayer perceptron neural networks (MLP). Several identification schemes have been developed. They are based on a MLP neural network composed of linear or multiple MLP networks with specific learning. Harmonics of a disturbed signal are identified with their amplitude and phases. They can be used to generate compensation currents fed back into the network to improve the waveform of the electric current. Neural approaches were developed to distinguish and to recognize the types of harmonics and is nonlinear load types that are at the origin. They consist of MLP or SVM (Support Vector Machine) acting as classifier that learns the harmonic profile of several types of predetermined signals and representative of non–linear loads. They entry are the parameters of current harmonics of the current wave. Learning can recognize the type of nonlinear load that generates disturbances in the power network. All harmonics identification and recognition approaches have been validated by simulation tests or using experimental data. The comparisons with other methods have demonstrated superior characteristics in terms of performance and robustness.

Rozptýlená výroba elektrické energie využívající obnovitelné zdroje, jako je sluneční energie, přispívá ke snížení emisí skleníkových plynů. Z hlediska provozu distribuční soustavy je také výhodné, aby energie byla primárně spotřebována v místě výroby. To je částečně možné přizpůsobením spotřeby, ale především využitím akumulačních systémů. V této práci je představen hybridní systém složený z fotovoltaické elektrárny, akumulátoru elektrické energie a akumulátoru tepelné energie. Výběr a parametry všech částí hybridního systému jsou popsány v práci. Akumulátor elektrické energie je navržen a sestaven z LiNiMnCoO2 článků a řídícího systému zajišťujícího bezpečný provoz. Řídicí systém akumulátoru (BMS) zajistí odpojení baterie, pokud je překročen některý z provozních parametrů baterie. Návrh baterie i sestavy je popsán v práci. Akumulátor tepelné energie sestává z výkonového spínače a nádrže na teplou vodu s topnou patronou pro odporový ohřev vody. Na základě rešerše komerčně používaných zařízení pro regulaci příkonu byly definovány jejich nedostatky a na základě nich bylo navrženo optimální řešení. Řešení spočívá v použití komerčního polovodičového spínacího prvku. Pro tento výkonový spínací prvek byla vytvořena zpětnovazební řídící smyčka s regulátorem výkonu, který byl implementován v prostředí softwaru LabVIEW. V práci je také uveden postup návrhu chladiče spínacího prvku a LCL filtru, který je klíčový pro splnění požadavků elektromagnetické kompatibility. V druhé části práce je popsán návrh nadřazeného řídícího algoritmu, jehož úkolem je řídit výkonové toky v hybridním systému tak, aby byly splněny požadavky definované jak uživatelem, tak i okamžitým stavem akumulátorů. Algoritmus byl implementován v prostředí LabVIEW. Funkčnost celého systému byla ověřena měřením v laboratorních podmínkách. Z výsledků plyne, že nadřazený řídící algoritmus funguje správně. Řídící smyčka tepelného akumulátoru je stabilní a reguluje zátěž na požadovanou hodnotu. Přidanou hodnotou je kratší reakční doba na změnu toku výkonu oproti hybridnímu měniči a díky tomu dochází k minimalizaci přetoků elektrické energie do distribuční sítě. Na práci je možné navázat rozšířením stávajícího algoritmu o možnost řízení/ovládání více typů akumulačních jednotek a generátorů nebo implementováním odlišných strategií řízení.

The installation of wind power plant has significantly increased since several years due to the recent necessity of creating renewable and clean energy sources. Before the accomplishment of a wind power project many pre-studies are required in order to verify the possibility of integrating a wind power plant in the electrical network. The creation of models in different software and their simulation can bring the insurance of a secure operation that meets the numerous requirements imposed by the electrical system. Hence, this Master thesis work consists in the creation of a wind turbine model. This model represents the turbines installed at Lillgrund wind farm, the biggest wind power plant in Sweden. The objectives of this project are to first develop an accurate model of the wind turbines installed at Lillgrund wind farm and further to use it in different kinds of simulations. Those simulations test the wind turbine operating according to different control modes. Also, a power quality analysis is carried out studying in particular two power quality phenomena, namely, the response to voltage sags and the harmonic distortion. The model is created in the software PSCAD that enables the dynamic and static simulations of electromagnetic and electromechanical systems. The model of the wind turbine contains the electrical machine, the power electronics (converters), and the controls of the wind turbine. Especially, three different control modes, e.g., voltage control, reactive power control and power factor control, are implemented, tested and compared. The model is tested according to different cases of voltage sag and the study verifies the fault-ride through capability of the turbine. Moreover, a harmonics analysis is done. Eventually the work concludes about two power quality parameters.

It is commonly agreed among energy experts that smart meters (SMs) are the key component that will facilitate the transition towards the smart grid. Fast-peace innovations in the smart metering infrastructure (AMI) are exposing countless benefits that network operators can obtain when they integrate SMs applications into their daily operations.  Following the amendment in 2017, where the Swedish government dictated that all SMs should now include new features such as remote control, higher time resolution for the energy readings and a friendly interface for customers to access their own data; network operators in Sweden are currently replacing their SMs for a new model, also called the second generation of SMs. While the replacement of meters is in progress, many utilities like Hemab are trying to reveal which technical and financial benefits the new generation of SMs will bring to their operations.    As a first step, this thesis presents the results of a series of interviews carried out with different network operators in Sweden. It is studied which functionalities have the potential to succeed in the near future, as well as those functionalities that are already being tested or fully implemeneted by some utilities in Sweden. Furthermore, this thesis analyses those obstacles and barriers that utilities encounter when trying to implement new applications using the new SMs. In a second stage, an alarm system for power interruptions and voltage-quality events (e.g., overvoltage and undervoltage) using VisionAir software and OMNIPOWER 3-phase meters is evaluated. The results from the evaluation are divided into three sections: a description of the settings and functionalities of the alarm, the outcomes from the test, and a final discussion of potential applications. This study has revealed that alarm functions, data analytics (including several methods such as load forecasting, customer segmentation and non-technical losses analysis), power quality monitoring, dynamic pricing, and load shedding have the biggest potential to succeed in Sweden in the coming years. Furthermore, it can be stated that the lack of time, prioritization of other projects in the grid and the integration of those new applications into the current system seem to be the main barrier for Swedish utilities nowadays. Regarding the alarm system, it was found that the real benefits for network operators arrive when the information coming from an alarm system is combined with a topology interface of the network and a customer notifications server. Both applications could improve customer satisfaction by significantly reducing outage time and providing customers with real-time and precise information about the problems in the grid.

This project is made for a deeper understanding ofhow frequency and amplitude of the waves that create the controlwave in a Pulse Width Modulated 2-level inverter affect the powerquality and power losses. The results were that a high frequencyreduces the Total Harmonic Distortion but increases the powerloss. The amplitude, however, reduces both the Total HarmonicDistortion and the power loss as it increases. All the analyseswere done in a simulation program called Simulink. The resultscan be applied when improving High Voltage Direct Currentinverters to develop a functional High Voltage Direct Currentgrid that enables wider use of renewable energy sources. / Projektet syftar till att få en djupare förståelse för hur frekvensen och amplituden på de vågor som skapar kontollvågen i en pulsbreddsmodulerad likspänningsomvandlare med två nivåer påverkar effektkvalitén och effektförlusterna. Resultatet av studien var att en hög frekvens minskar ”Total Harmonic Distortion” men ökar effektförlusterna. Amplituden å andra sidan reducerar både ”Total Harmonic Distortion” och effektförlusterna när den ökar. Alla analyserna är gjorda i simuleringsprogrammet Simulink. Resultaten kan appliceras när högspända likspänningsomvandlare vidareutvecklas för att skapa ett fungerande högspänt-likströms elnät som öppnar upp för en bredare användning av förnyelsebara energikällor. / Kandidatexjobb i elektroteknik 2020, KTH, Stockholm

The electric power supply industry has evolved into one of the largest industries. Even though secure and reliable operation of the electric power system is fundamental to economy, social security and quality of modern life, the complicated power grid is now facing severe challenges to meet the high-level secure and reliable operation requirements. New technologies will play a major role in helping today's electric power industry to meet the above challenges. This dissertation has focused on some key technologies among them, including the emerging technologies of energy storage, controlled power electronics and wide area measurement technologies. Those technologies offer an opportunity to develop the appropriate objectives for power system control. The use of power electronics based devices with energy storage system integrated into them, such as FACTS/ESS, can provide valuable added benefits to improve stability, power quality, and reliability of power systems. The study in this dissertation has provided several guidelines for the implementation of FACTS/ESS in bulk power systems. The interest of this study lies in a wide range of FACTS/ESS technology applications in bulk power system to solve some special problems that were not solved well without the application of FACTS/ESS. The special problems we select to solve by using FACTS/ESS technology in this study include power quality problem solution by active power compensation, electrical arc furnace (EAF) induced problems solution, inter-area mode low frequency oscillation suppression, coordination of under frequency load shedding (UFLS) and under frequency governor control (UFGC), wide area voltage control. From this study, the author of this dissertation reveals the unique role that FACTS/ESS technology can play in the bulk power system stability control and power quality enhancement in power system. In this dissertation, almost all the studies are based on the real system problems, which means that the study results are special valuable to certain utilities that have those problems. The study in this dissertation can assist power industry choose the right FACTS/ESS technology for their intended functions, which will improve the survivability, minimize blackouts, and reduce interruption costs through the use of energy storage systems. / Ph. D.

Les énergies renouvelables, l’énergie sous la forme électrique et son transport à l’aide de réseaux électriques intelligents représentent aujourd’hui des enjeux majeurs car ils ont de grands impacts environnementaux et sociétaux. Ainsi, la production, le transport et la gestion de l’énergie électrique, continuent toujours à susciter un intérêt croissant. Pour atteindre ces objectifs, plusieurs verrous technologiques doivent être levés. Au-delà des questions liées aux architectures des réseaux électriques, aux modèles, aux outils de dimensionnement, à la formalisation de caractéristiques et d’indicateurs, aux contraintes et aux critères, à la gestion et à la production décentralisée, la qualité de la puissance électrique est centrale pour la fiabilité de l’ensemble du système de distribution. Les perturbations affectent la qualité des signaux électriques et peuvent provoquer des conséquences graves sur les autres équipements connectés au réseau. Les travaux de cette thèse s’inscrivent dans ce contexte et de fait ils sont orientés vers le développement de modèles, d’indicateurs et de méthodes de traitement des signaux dédiés à la surveillance en temps-réel des performances des réseaux de distribution électrique.Cette thèse analyse la qualité de la puissance électrique, en prenant en compte plusieurs caractéristiques bien connues ainsi que leur pertinence. Les modèles des systèmes électriques et les méthodes de traitement du signal pour estimer leurs paramètres sont étudiés pour des applications en temps-réel de surveillance, de diagnostic et de contrôle sous diverses conditions. Parmi tous, la fréquence fondamentale est l’un des paramètres les plus importants pour caractériser un système de distribution électrique. En effet, sa valeur qui est censée être une constante, varie en permanence et reflète la dynamique de l’énergie électrique disponible. La fréquence peut également être affectée par certaines productions d’énergie renouvelable et peut être influencée par des mauvaises synchronisations de certains équipements. En outre, la puissance absorbée par les charges ou produite par des sources est généralement différente d’une phase à l’autre. Évidemment, la plupart des installations électriques existantes avec plusieurs phases, qu’elles soient résidentielles ou industrielles, travaillent dans des conditions déséquilibrées. Identifier les composantes symétriques de tension est dans ce cas un moyen pertinent pour quantifier le déséquilibre entre les phases d’un système électrique.De nouvelles représentations de type espace d’état et modélisant des systèmes électriques sont proposées pour estimer la fréquence fondamentale et pour identifier les composantes symétriques de tension des systèmes électriques triphasés et déséquilibrés. Le premier modèle d’espace d’état proposé considère la fréquence fondamentale comme connue ou obtenue par un autre estimateur. En contrepartie, il fournit les autres paramètres caractérisant le système électrique. Un second modèle d’état-espace est introduit. Il est original dans le sens où il ne nécessite aucune connaissance de la fréquence fondamentale. Une de ses variables d’état est directement reliée à la fréquence et permet donc de la déduire. En outre, ce nouvel espace d’état est parfaitement capable de représenter des systèmes électriques à trois phases équilibrés et non équilibrés. [...] / Renewable energy, electricity and smart grids are core subjects as they have great environmental and societal impacts. Thus, generating, transporting and managing electric energy, i.e., power, still continue to drive a growing interest. In order to properly achieve these goals, several locks must be removed. Beyond issues related to the distribution architecture, the formalization of models, sizing tools, features and indicators, constraints and criteria, decentralized generation and energy management, power quality is central for the whole grid’s reliability. Disturbances affect the power quality and can cause serious impact on other equipment connected to the grid. The work of this thesis is part of this context and focuses on the development of models, indicators, and signal processing methods for power quality monitoring in time-varying power distribution systems.This thesis analyzes the power quality including several well-known features and their relevance. Power system models and signal processing methods for estimating their parameters are investigated for the purpose of real-time monitoring, diagnostic and control tasks under various operating conditions. Among all, the fundamental frequency is one of the most important parameters of a power distribution system. Indeed, its value which is supposed to be a constant varies continuously and reflects the dynamic availability of electric power. The fundamental frequency can also be affected by renewable energy generation and by nasty synchronization of some devices. Moreover, the power absorbed by loads or produced by sources is generally different from one phase to the other one. Obviously, most of the existing residential and industrial electrical installations with several phases work under unbalanced conditions. Identifying the symmetrical components is therefore an efficient way to quantify the imbalance between the phases of a grid. New state-space representations of power systems are proposed for estimating the fundamental frequency and for identifying the voltage symmetrical components of unbalanced three-phase power systems. A first state-space representation is developed by supposing the fundamental frequency to be known or to be calculated by another estimator. In return, it provides other parameters and characteristics from the power system. Another original state-space model is introduced which does not require the fundamental frequency. Here, one state variable is a function of the frequency which can thus be deduced. Furthermore this new state-space model is perfectly are able to represent a three-phase power system in both balanced and unbalanced conditions. This not the case of lots of existing models. The advantage of the proposed state-space representation is that it gives directly access to physical parameters of the system, like the frequency and the amplitude and phase values of the voltage symmetrical components. Power systems parameters can thus be estimated in real-time by using the new state-space with an online estimation process like an Extended Kalman Filter (EKF). The digital implementation of the proposed methods presents small computational requirement, elegant recursive properties, and optimal estimations with Gaussian error statistics.The methods have been implemented and validated through various tests respecting real technical constraints and operating conditions. The methods can be integrated in active power filtering schemes or load-frequency control strategies to monitor power systems and to compensate for electrical disturbances.

Esta pesquisa propõe uma metodologia de alocação otimizada de monitores da Qualidade da Energia Elétrica (QEE) em sistemas de distribuição, de modo que estes sejam sensíveis tanto às variações de tensão de curta duração, bem como às potenciais condições de ressonância harmônica. A metodologia de alocação dispõe da aplicação do Método de Posição de Faltas (MPF) e da Análise de Ressonância Harmônica Modal (ARHM) para a construção de uma matriz binária de cobertura. Esta matriz é então utilizada pelo processo de otimização para a determinação dos melhores locais de instalação dos monitores, garantindo assim o completo monitoramento dos distúrbios da QEE considerados. A partir do MPF, é estudado o comportamento das tensões nodais remanescentes do Sistema de Distribuição (SD) em análise frente a situações de curtos-circuitos que provocam afundamentos e /ou elevações de tensão. Pela ARHM, as impedâncias modais associadas ao modo crítico são calculadas para a identificação das respectivas frequências de ressonância harmônica do SD. Além disso, a partir dos autovetores críticos, associados ao modo crítico, também se obtém o grau de observabilidade das condições de ressonância para cada nó do SD. A otimização minimiza a quantidade necessária de monitores para a completa observação dos distúrbios de QEE considerados, e é formulada como um modelo de programação linear inteira com variáveis binárias. Para a resolução deste problema de otimização utilizou-se o algoritmo Branch and Bound. A metodologia foi testada para um SD de 15 nós, baseado em uma rede do CIGRÉ, e para um SD de 24 nós, baseado no SD de 34 nós do IEEE. Os resultados apontam a necessidade de instalação de 2 a 4 monitores para o SD de 15 nós, e de 2 a 9 monitores para o SD de 24 nós, para a completa observabilidade dos distúrbios de QEE considerados. A metodologia de alocação otimizada de monitores de QEE apresenta-se como uma ferramenta auxiliar para o planejamento de um sistema de monitoramento que promova meios para a melhoria dos índices de QEE. / This research proposes an optimized allocation methodology of Power Quality (PQ) meters in Distribution System (DS), considering short duration voltage variations and potential harmonic resonance conditions. The allocation methodology uses the Fault Position Method (FPM) and the Harmonic Resonance Modal Analysis (HRMA) in order to obtain a binary covering matrix, which is lately used by the optimization process. The optimization process determines the best installation nodes of the minimum number of PQ monitors that complete observe the considered PQ disturbances. From the FPM, the behavior of the remaining nodal voltages is studied for different short-circuit situations, which cause voltage sags and/ or swells. The HRMA is used to calculate the modal impedances related to the critical modes and identify the respective harmonic frequencies of the DS. Moreover, from the critical eigenvectors, associated with the critical mode, it is also obtained the observability level of the respective harmonic resonance frequencies. The allocation problem is modeled as an integer linear programming that minimizes the number of necessary PQ meters, ensuring the complete observation of the considered PQ disturbances. The optimization is performed using a Branch and Bound algorithm. The allocation methodology was tested for a 15 nodes DS based on a CIGRÉ network, and for 24 node DS derived from the IEEE 34 node test system. Results indicate that 2 to 4 PQ monitors are required for the 15 nodes DS, and 2 to 9 PQ monitors for the 34 DS in order to completely observe the considered PQ disturbances. The allocation methodology presentes itself as an auxiliary tool for the PQ monitoring planning, which may leads to the improvement of the PQ indices.